The basic tactical principles of the Japanese Army have been carefully developed from studies of foreign army techniques and its own valuable experiences gained in combat under varying conditions. Japanese forces have fought against regular military organizations of several first-class nations and have had considerable experience in combating the constant harassing action of guerrillas on supply lines and rear areas.
TACTICS OF THE JAPANESE ARMY
They have engaged in tank actions on the plains of Manchuria and in mountain battles in Central and Southern China; they have conducted landing operations under varying conditions of terrain and climate. They have been highly successful in their earlier jungle operations, on terrain where good roads and railroads are practically unknown, and where every type of natural obstacle exists. They are not merely jungle fighters, however, for much of their success has been on terrain where principles of open warfare have been applied effectively. By studying the areas over which they expected to operate they effectively organized, trained, and equipped their forces and evolved techniques designed in each case to fit the terrain and meet the logistical requirements peculiar to their own army.
The Japanese lay great stress on offensive actions, surprise, and rapidity of movement, with all commanders and staffs operating well forward in order to keep themselves constantly informed of the situation. Their tactical doctrine is based on the principle that a simple plan, carried through with power and determination, coupled with speed of maneuver, will so disrupt the plans of hostile forces that success will ensue. Combat orders, in both attack and defense, from the highest to the lowest unit, generally carry the admonition that the "enemy forces will be annihilated." Surprise is an ever present element, while the envelopment is the preferred form of attack. Thorough reconnaissance also is taught, and the practice of infiltration is greatly stressed. The Japanese willingness to attack a position with forces which other nations would consider insufficient for the task, is based on the assumption of their so-called military superiority. An explanation of thi assumption calls for an analysis of Japanese psychology, national vanity, and past military successes, which is beyond the scope of this study. To the Japanese officer, considerations of "face" and "toughness" are most important, and they are therefore prone to indulgence in "paper" heroics. They have evinced boldness against poorly equipped troops; however, against first-class, well-equipped forces, it may be expected that they will adopt more circumspect methods.
Despite the opportunities presented during 6 years of active combat, the Japanese have continued to violate certain fundamental principles of accepted tactics and technique. Their tendency to persist in such violations is based primarily upon their failure to credit the enemy with good judgment and equal military efficiency. Whether or not they have profited by recent experiences remains to be seen.
General Tactical Doctrine
1. GENERAL. The part on the General Tactical Doctrine of the Japanese Army is based on actual observation of their field maneuvers, and map problems, their operations against Russia and China, and a study of their field manuals. It is believed that their tactical principles, taught and studied for years, will not change materially. The tactical methods described here are primarily those which the Japanese consider appropriate for fighting in open country such as North Asia. They have had ample opportunity to test their tactics and to observe those employed by other Armies. Any study of theirteachings must be approached with the knowledge that the Japanese are quick to copy and may even improve on the tactics of their enemies. Technique or application of tactical principles, will vary, and is limited only by the imagination and initiative of individual commanders.
Section I. GENERAL
Section II. OFFENSIVE
1. DOCTRINE. Japanese tactical doctrine insists vigorously on the inherent superiority of the offense, and Field Service Regulations state that the offensive should be resolutely taken. The object of all maneuver is to close quickly with the enemy
so that the assumed Japanese superiority in close combat can be realized to the utmost. Even when the enemy strength is markedly superior, or when the Japanese commander has been placed temporarily on the defensive, he is supposed to use every effort to regain the offensive and take the initiative. The Japanese seem to feel that there is some mystic virtue in the attack and defensive combat is looked upon as a negative form of action to be adopted only when confronted with a markedly superior enemy. Even in defense, the offensive principle is strongly emphasized. Both as a result of this training and because of faith in the offensive doctrine, Japanese officers often reach attack decisions where, by all orthodox tactics, the situation patently requires some form of defensive action. Their teachings have been found to place very little emphasis on time and space factors, with the result that concentration of effort and the cooperation of all arms are frequently neglected. The division used for illustrative purposes in this section is the Japanese triangular division. It should be borne in mind, however, that while all Japanese divisions are not identically organized, tactics will not materially differ, although there will be differences in composition of columns and grouping of units.
2. FORMS OF ATTACK. a. Envelopment. (1) The Japanese consider the envelopment as the preferred offensive maneuver. Envelopment will be accompanied by a determined frontal pressure, while the main force attacks a flank. In ascending order of effectiveness, the envelopment may be single, double, or a complete encirclement (kanzen hoi). Contrary to generally accepted tactical principles, the Japanese are willing to try a double envelopment without any considerable numerical superiority and regard it as possible, sometimes, even by an inferior force which relies on surprise and deception. The Japanese commander may seek to obtain envelopment in one of several ways.
(a) The force advances in two or more parallel columns, with one or more columns directed toward the enemy flank and rear during the advance to contact.
(b) The force advances with certain units in the rear which can later be deployed to execute a flank envelopment.
(c) After the force has encountered the enemy and partially deployed, some units may be moved laterally for envelopment if natural cover, darkness, fog, or smoke are available.
(2) The procedure of (1) (a) above is considered the normal one for units of the size of a division; (1) (b) is especially applicable to small units, but (1) (c) is considered feasible only under most favorable conditions. Those units of a division executing the frontal holding attack often will make a close-in envelopment in performing their mission. Units of this force, such as squads and platoons, seek to obtain the effect of flanking fire (shageki hoi).
(3) The question of which flank to envelop is decided by weighing normal factors such as terrain, location of hostile reserves and heavy weapons, etc.
(4) To increase the effectiveness of the envelopment the Japanese often send a small force around to attack the enemy rear. When such a movement (ukai) is employed, the force sent around by a division in attack is relatively weak, comprising about a battalion reinforced by light artillery and a squad of engineers. The mission of such a turning force is often similar to that of a pursuit detachment; in fact this force may become a pursuit detachment if the main attack succeeds.
b. Frontal attack. (1) Japanese regulations contain the usual admonitions against a frontal attack. Situations which may give rise to a frontal attack are those to which Allied armies are accustomed. In observed practice, however, the time element, or the fear of allowing the enemy leisure to improve his position, often is allowed to justify a questionable decision to make a frontal attack.
(2) The main effort of a frontal attack is made against a "soft spot" in the line, leading in a decisive direction into the enemy rear areas. Effort will be made to penetrate deeply and swiftly at the first attempt by keeping narrow the battle fronts of units in the area of the main attack, making dispositions in depth, and coordinating employment of artillery. Tanks, if available, may participate. In general the Japanese are weak in artillery support and depend heavily on extensive employment of their infantry guns and infiltration practices.
c. Comments. The impressions gained from a study of Japanese teachings on the forms of attack and their application in practice show that:
(1) The Japanese will attack in many cases where the orthodox decision would call for less positive action. The attack may be rash and costly but will never lack vigor and determination.
(2) The frontal attack, often with inadequate supporting arms, is not uncommon.
3. MEETING ENGAGEMENT (ENCOUNTER). a. Doctrine. The meeting engagement is the foundation of Japanese combat training, with official regulations giving more space to it than to any other form of combat. Japanese military writings define the meeting engagement as the collision of two hostile forces in motion, or the meeting of a force in motion with one which has halted but has not had time to organize a detailed position. Training strongly emphasizes this form of combat as allowing the optimum development of the alleged Japanese aptitude for swift and decisive offensive action.
b. Artillery seems to be assigned missions in excess of its capabilities. Aircraft are expected to conduct constant reconnaissance of the situation of enemy and friendly troops as well as to cooperate with the artillery. Tanks may be used independently or in direct support of the infantry; when they are
sent on distant raids, other mobile units, if available, may accompany them.
c. The rules governing the Japanese in the meeting engagement may be summarized as follows:
(1) The seizure and retention of the initiative.
(2) Bold, independent action by subordinate commanders.
(3) Prompt occupation of important terrain features.
(4) Energetic leadership during combat.
d. In the words of a Japanese writer, "The Imperial Army seeks to wage a short war to a quick and decisive conclusion. The meeting engagement conforms to this spirit and is to be sought whenever possible."
4. ADVANCE. a. General. The formations in the advance in day or night movements are similar to those used by other Armies and are governed by the same considerations. Parallel columns, each self-contained, are usual, unless precluded by the road net. When the enemy is strong in aviation and mechanized units, long columns are broken up into short serials containing antiaircraft and antitank weapons. Each main column is preceded by an advance guard, while the division cavalry, if present, usually acts as a reconnaissance screen in front of the advance guards. When the division is to advance at night, the division commander often sends forward in daylight a reconnaissance detachment and motorized infantry to seize important terrain features and to cover the night movement. As a meeting engagement becomes likely, the division commander modifies the formation, as needed, to facilitate the entry of the division into action with a view to enveloping one or both flanks of the enemy.
b. Advance in two columns.
(1) A study of Japanese tactical problems illustrates the division advancing in one, two, and three columns, with the two-column formation being the most favored. In the two-column formation the essential components of the division are disposed as follows:
Reconnaissance Detachment 1st Cavalry
Left column Right column
1st Infantry Regt. (less 3d Bn)
1st Co 1st Ind Antitank Bn
1st Bn 1st FA Regt
1st Co 1st Engr Regt
1/3 Decontamination Unit
1/3 Casualty Clearing Unit
2d Infantry Regt (less 3d Bn)
2d Co 1st Ind Antitank Bn
2d Bn 1st FA Regt
1st Engineers (less 1st Co)
1/3 Decontamination Unit
1/3 Casualty Clearing Unit
Main BodyDivision Headquarters
Infantry Group Headquarters
1st Troop (Company) 1st Cavalry Regt
3d Bn 2d Infantry Regt
1st FA Regt (less 1st and 2d Bns)
1st Ind Antitank Bn (less 1st and 2d Cos)
1st Bn 1st Med FA Regt (150 mm Howitzer)
3d Infantry Regt
3d Bn 1st Infantry Regt
Advance Section, 1st Transport Regt
1st Transport Regt (less detachment)
1/3 Decontamination Unit
1/3 Casualty Clearing Unit
With the above formation, the division commander expects, if anticipatory plans have been correct,
to execute an envelopment of the hostile left flank.
(2) The composition of the march column illustrated above is covered in the division field order. It is noteworthy that an advance guard is designated by the division commander for the right column only; the left column merely receives an indication of the units composing it. This march formation is the result of the curious system of command which the Japanese employ. The division commander concurrently commands the division and the right column. In the latter capacity, he prescribes the detailed organization of the right column. The detailed organization of the left column falls to the senior commander of that column who designates an advance guard for its protection. Thus the advance guard of the left column is not an instrumentality for the protection of the division as a whole and is not directly under the control of the division commander. Therefore, as a meeting engagement becomes imminent, the immediate subordinates to whom the division commander issues orders directly are the colonel of the 1st Cavalry Regiment (commanding the reconnaissance detachment), advance guard commander (right column), commanders of the major components of the right column, and the commander of the left column. It is not clear how the division commander plans to coordinate the action of his right column advance guard with that of the left column. The term "advance guard" as subsequently used applies only to that which is controlled directly by the division commander.
(3) In the above formation, the infantry strength in the advance guards of the 2 columns is about one-third of the division's infantry. When there is a greater number of columns employed, the combined infantry strength of the advance guards sometimes reaches half that of the division. Strong advance guards are characteristic of the Japanese Army in approaching a meeting engagement.
c. Advance in other than two columns. An advance in one column is avoided because of the delay incident to developing the division for an attack. Therefore whenever that formation is adopted it is imposed by limitations of the road net. An advance in 3 columns was undertaken by a Japanese
infantry division at Rangoon in March 1942, as follows:
Left Center Right One Bn Inf (less one Co). One Inf Regt (less one Bn--less one Co). Inf Regt. One Co Engrs (less one Pl) with collapsible boats. One Co FA (Pack) with Ind Tpt Unit. One Bn FA (Pack) (less one Co). Tpt Unit (less detch). One Co Engrs (less one Pl). One Pl Engr. Div Med Unit (less detch). One Ind A/Tk Co (37-mm). Water Pur Unit (less detch). Detch Div Med Unit. Detch Water Purif Unit. One Co Army Sig Troops. One Co Ind Tpt Unit. Two Sections Div Sig Unit. One Section Div Sig Unit. Figure 81.
The whereabouts of the remainder of the division is not known. The above illustration is taken from a British source which states that the initial advance of the division was made by 2 regiments, i.e., 6 battalions, spread over a frontage of 40 miles. The 3 columns were divided with approximately a 20-mile space between each. In this case the left column hardly could be considered as self contained. Use was made of roads, trails, and waterways wherever possible. In advance in 3 columns, the division commander remains the commander of the strongest column. More than 3 columns may be found, but such employment will be exceptional.
d. Transport and trains. The division transport and trains normally follow the main columns of the division under division control in the following order: advance section transport regiment, unit trains, and the remainder of the transport regiment. Distances between these units are normally from 1 to 2.5 miles. The massed trains are under a commander, who is designated by the division commander. The advance section of the transport regiment consists of an infantry ammunition section, 2 artillery ammunition sections, and a veterinary section. Two field hospitals may be attached to the advance section of the transport regiment.
e. Attachments. Units of light and medium artillery, antiaircraft artillery, observation aviation, antitank units and other supports frequently are attached to a division in the advance.
f. Antiaircraft protection on march. For the advance, each front-line division may have attached an antiaircraft organization. This unit, often motorized, moves by leapfrogging from critical point to critical point along the axis of the division's advance. The guns go into position during the noonday halt, while passing defiles, while in bivouac, etc. If possible, antiaircraft units move forward by roads not used by the other elements of the division. The effective radius of action of one company of 75-mm antiaircraft artillery is considered to be 6,800 yards.
g. Antitank protection on the march. In areas where there is a threat of enemy tank action against a column, the Japanese usually hold sometanks in readiness for employment against hostile tank forces. Active reconnaissance by both air and cavalry units warns the division commander of impending hostile tank action. Antiaircraft artillery may at times be employed to supplement normal antitank protection measures.
h. Advance detachments. (1) There is a notable tendency for the division commander to send forward a mobile detachment in advance of the division for one of the following purposes:
(a) To cover a night march to the probable battlefield where the division expects to be committed to action shortly after daylight.
(b) To secure a vital terrain feature on the front of the division.
(c) To execute demolitions of the road net and hamper the movement of the enemy.
(d) To execute surprise attacks while the enemy is in march formation.
(2) These detachments generally consist of the division cavalry, some infantry and engineers in trucks, and a company of light artillery. The infantry strength ordinarily will not exceed a regiment, except where the division plans an active defense. In this latter case, as much as half of the division may be pushed forward by forced marches to occupy a defensive position, while the remainder of the division follows more slowly with the intention of launching a counter-offensive against an enemy flank.
5. ACTIONS OF THE DIVISION COMMANDER IN APPROACHING A MEETING ENGAGEMENT. a. Reconnaissance. The formation of the advancing division contains in it the germ of the maneuver which the division commander expects to adopt if he encounters the enemy on the march. When the hostile force is reported approaching from a considerable distance, the division commander estimates where the battle will occur and communicates to his subordinates the general plan of maneuver which he expects to adopt, taking into consideration the use of terrain which the enemy considers generally impassable. He indicates time and place for the delivery of reports and designates a message dropping ground for the air service. His artillery and engineer commanders receive technical information from their own patrols marching with the advance guard and reconnaissance detachment. As contact becomes imminent the division commander, hitherto marching at the head of the main body of the principal column, moves forward on personal reconnaissance accompanied by appropriate staff officers. An advance message center may be designated behind the advance guard, one of the important functions of which is to facilitate collection and dissemination of enemy information.
b. Orders. From his personal reconnaissance and the reports of his reconnaissance agencies, the division commander determines the area in which the division will make its decisive effort, the plan of maneuver, and the location of the division command
post. He then issues fragmentary operational orders to initiate deployment of the division. Japanese Combat Regulations warn against waiting for over-detailed information before reaching a decision, and this injunction seems to authorize a very short reconnaissance phase at this point.
6. DEPLOYMENT OF DIVISION. a. Advance guard. (1) (a) The advance guard in the meeting engagement performs the following functions: it secures enemy and terrain information needed to form the basis of the decision of the division commander; it protects the deployment of the main body; and secures important terrain features to facilitate the subsequent attack.
(b) The advance guard commander, bearing in mind these general functions, is expected to exercise initiative and boldness of action in specific cases. He obtains the necessary information by vigorous patrolling and, if necessary, by a small-scale attack. He protects the deployment of the division, either by offensive or defensive methods, and attacks when necessary to obtain important geographical points. Left to his own devices, however, the advance-guard commander usually elects to drive headlong into the advancing enemy, unless specifically restrained by division order.
(2) As the advance guard closes to contact, its artillery prepares to furnish continuous support by leapfrogging from position to position in rear of the infantry. Normal artillery missions are to interdict (harass) the movement of enemy columns, to support the action of the advance guard infantry, and to perform limited counter-battery missions. Extreme ranges for interdiction by the 75's are 7,500 to 9,000 yards, but in practice missions are seldom fired at over 5,500 yards. Positions are chosen with a view to supporting the attack of the main body without change of position. The advance-guard artillery reverts to the control of the artillery commander at the time of the attack of the main body.
(3) It must be borne in mind that the advance guard discussed is that of the column directly commanded by the division commander. The security detachments in advance of other columns are for their local protection only.
b. Main body. (1) Deployment (a) In his basic decision for the deployment of his division, the division commander determines whether it will be coordinated or piecemeal. The basis for this decision is found in the Japanese Combat Regulations, a translation of which reads:
"The division commander, in order to profit by or to extend an advantage won by the advance guard, may have to commit to combat each march column and each element of the main body successively upon arrival. However, if the situation permits, the division commander should seek the coordinated entry into action of his units, in which case he orders the deployment of each unit, establishes close cooperation between infantry and artillery, and coordinates the time of the infantry attack."
(b) The question of whether to make a piecemeal attack thus appears to be decided largely by the success of the advance guard action. In map problems studied, the piecemeal engagement of all or part of a force often is justified by the necessity of seizing some prominent terrain feature or by the desire to get out of a defile. The object of the piecemeal attack is to take advantage of a sudden opportunity, while the coordinated attack aims at securing effective use of the combined arms at the expense of time.
(2) Coordinated deployment. (a) As indicated above, the Japanese prefer a coordinated development "if the situation permits." The measures taken by the division commander to secure this coordination are: the assignment of a line of departure (tenkaisen) behind which the major units of his command are to deploy for the attack; detailed arrangements to assure coordination between the artillery and the infantry; and announcement of an hour of crossing the line of departure. The line of departure is usually an extension of the line held by the advance guard. If the enemy has secured the advantage of priority in deployment, the main body of the division may endeavor to escape a threatened envelopment or premature engagement with superior numbers by deployment along a line behind the advance guard or to the flank and rear thereof. In the event the deployment is to the flank and rear, the advance guard supported by all the division artillery covers the deployment and delays the advance of the enemy.
(b) If the enemy, in anticipation of a collision with the Japanese troops, assumes the defensive, the deployment is modified to resemble the relatively cautious procedure of the attack of a position. In this case also the division commander tries to develop and attack in the same day to avoid giving the enemy time to improve his position.
(c)The phase of the passage from march column to complete deployment is indicated by the following nomenclature used in Japanese regulations: (It must be realized that the following definitions are the translation of the Japanese and do not necessarily bear the same connotations in the Allied terminology.)
- Bunshin. Breaking from march columninto small ones out of hostile artillery range at the beginning of the approach march.
- Tenkai. Deployment along a line of departure (tenkaisen) with a view to performing an assigned combat mission.
- Sokai. Advance from the tenkaisen insmall (squad or section) columns.
- Sankai. Final deployment of front-line units to permit firing during the last few hundred yards of the assault.
These phases are shown diagrammatically in figure 82:
(d) It is important to note that the coordinated attack from the Japanese point of view does not imply passing into assembly areas. However, this passage into assembly areas, called "kaishin" usually is observed in the attack of a position. If a coordinated attack follows the meeting engagement columns deploy directly behind the line of departure (tenkaisen) without halting prior to arriving on it. No special time is allotted for ammunition issue and final reconnaissance.
(3) Piecemeal attack. (a) In the piecemeal attack the troops are committed to action in order of their arrival on the field. The division commander, decentralizing control to his column commanders, limits himself to a designation of routes of advance with a view to subsequent attack in the desired directions. No division "tenkaisen," no common hour of attack, and no detailed plans for coordination between the various arms are stipulated.
(b) Despite the lip service rendered in regulations to the coordinated deployment and attack, the piecemeal method is very common on the map, n the maneuver ground, and in observed operations. Often this is the result of the precipitate action of the advance guard commander who gets himself seriously engaged on his own initiative. In such a case, a sort of hybrid deployment sometimes is executed, with a part of the main body going in piecemeal to help the advance guard, while the remainder makes an orderly deployment. Occasionally, a column commander has been known to stage a piecemeal attack all of his own in a situation where the prompt seizure of a terrain feature on his frontseemed essential to the subsequent success of the division. Such action was taken without waiting for orders or authorization from the division commander.
(c)The rate of march of the infantry as it enters the zone of effective hostile artillery fire is reduced. In this zone the artillery moves forward by bounds of battalions while furnishing continuous support to the infantry. The theoretical rate of movement forward for this artillery is 2.5 miles per hour, although this may be increased to about 5 miles per hour if a battalion is allotted a road for its exclusive use. As the range limit is reached the battalion prepares to move forward.
(d) Unit trains. When contact becomes imminent the transport regiment and the unit trains are halted in a sheltered location. The advance section of the transport regiment will often be as close as 2.5 miles to the anticipated contact, while the trains are normally about 5 to 6 miles in the rear of this line. The remainder of the transport regiment will be behind the trains.
7. DIVISION ATTACK ORDER. a. Deployment. The division deployment order gives a combat mission to the advance guard and march directions to the several columns with a view to executing a preconceived maneuver. While the elements of his command are carrying out these orders, the division commander watches the development of the advance-guard action and, with a minimum of delay, issues a verbal attack order to his principal subordinates.
b. Attack order. The division attack order generally is issued in fragmentary form to the commanders concerned.
c. Orders to infantry. In the organization of the infantry for combat, the advance-guard infantry becomes one wing and executes the holding attack. The second regiment executes the main attack, and it may deploy as the other wing along a line of departure (tenkaisen), generally in prolongation of the advance guard position. About one regiment of infantry is held in division reserve. This attack order is issued when the enemy is fixed in a given area where contact is expected, but often prior to making actual contact and before the advance guard has developed the situation. The order assigns to the infantry wing(s) specific objectives or a very general attack mission, depending upon the degree of clarity of the situation. Specific objectives would be such as "to attack the hostile forces on X ridge and seize the X position," while a general attack mission might be something like "to advance in the direction of Y and locate and attack the enemy's right flank." This latter type of objective is appropriate in an obscure situation when the plan of maneuver is predicated largely on a tudy of the terrain. In this case the attack direction given is one which is certain to take in flank any formation or position which the enemy may reasonably assume. A study of Japanese attack orders
reveals that in an extreme case an order was issued 7.4 miles from the expected point of contact of the advance guards.
d. Orders to artillery. (1) The artillery order indicates the location of the positions in general terms, and detailed reconnaissance is made by artillery commanders to determine the exact locations. Attachment of artillery to infantry is considered to be justified when:
(a) The front of attack is very wide.
(b) Liaison with the infantry is difficult.
(c) Combat begins unexpectedly.
(d) The terrain is broken and wooded.
(2) In the normal case the division retains control of the artillery and coordinates its action. Typical missions during the successive phases of the combat are as follows:
(a) Phase I. During the approach march and deployment.
- Objectives (targets) in order of importance. Hostile artillery and machine guns firing at extreme ranges.
- Purpose. To cover the deployment of the infantry.
(b) Phase II. During the attack.
- Objectives (targets) in order of importance. Hostile infantry, artillery, and reserves.
- Purpose. Close support of infantry.
(c) Phase III. During final assault.
- Objectives (targets) in order of importance. The area of the decisive attack; the enemy reserves.
- Purpose. Neutralization and interdiction (harassing) of movement of reinforcements.
e. Orders for piecemeal attack. The division attack order described in the foregoing applies to the coordinated attack. In the piecemeal engagement columns are organized into wings and receive attack directions and the attachment of the proper auxiliary arms. There is no coordinated deployment of any unit larger than a battalion. The artillery, less detachments, is kept under division control. The maneuver takes the form of a frontal collision without any effort to coordinate direction of the various columns to obtain the effect of envelopment.
8. FRONTAGES AND DISTANCES. a. Frontages. The following frontages are averages derived from studies of several problems:
Battalion as a covering force 1,600 yards. Regiment in a holding attack 3,000 to 4,400 yards. Regiment in the decisive attack 1,600 to 2,200 yards.
b. Distances. Distances from the line of departure.
Division command post 2,200 to 3,300 yards. Artillery positions 600 to 1,500 yards. Division reserve 1,200 to 2,800 yards. Advance echelon, division transport 4,500 to 6,500 yards. Unit trains 8,800 to 11,000 yards. Remainder of division transport 11,000 to 13,000 yards.
c. Assault. Attacking units do not try to retain alignment, and where the going is easy they press ahead. When gassed areas may be encountered the leading wave includes decontamination squads. A gassed area is avoided when possible; if it must be traversed, the local gas squads use their light decontaminating equipment to neutralize it. When such equipment is insufficient or absent, the troops are taught to cross the gassed area resolutely at an increased gait. The artillery advances by bounds close behind the infantry, while its forward observers advance with the infantry. As the attacking infantry approach the enemy positions, infantry and artillery fire is increased, and reserve units are brought up. The cavalry closes in on the enemy flank and rear, and victory is won by closing with the bayonet. The division reserve is used to extend and exploit an advantage gained, to meet a counterattack, or to extend the flank of the enveloping forces. If darkness interrupts the attack, it will be continued at night or renewed at dawn.
9. COMMENTS. a. Meeting engagement. In the Japanese meeting engagement all elements of the division show boldness and vigor. Speed in decision and execution is stressed in regulations and carried out in application. A commander encountering a Japanese division may expect to receive a quick and energetic attack, and, unless his covering forces are solidly deployed on their position, the Japanese attack is likely to upset his own plans for a coordinated attack.
b. Piecemeal action. In practice the Japanese have shown an excessive willingness to engage in piecemeal action; Allied combat regulations, on the other hand, strongly favor the coordinated attack. Generally, according to Allied doctrine, the piecemeal attack is considered justifiable only if time is pressing, if there is a limited objective, and if combat superiority is on the attacker's side. If these criteria are applied to the situations in which the Japanese commander has decided to make a piecemeal attack, it will be found that time is pressing, and there is usually a limited objective, but not necessarily superiority. In fact, in the problems studied, the enemy was always superior, and in at least an equal state of readiness for combat. (In one map problem, the Japanese division was marching in one column while the enemy was in two). The only combat superiority was in the mind of the Japanese
commander. Such a doctrine tends to make wasteful, piecemeal action the rule rather than the exception and develops a dangerous over-confidence, unjustified when faced by first-class troops.
c. March formation. The march formation in which the division commander is also a column commander is awkward, for it needlessly burdens the division commander with the details of organizing and commanding a column. It complicates the handling of the advance guards which are usually not coordinated under division control. In fact, the advance guards of columns adjacent to the one commanded by the division commander generally are ignored in the division plan of maneuver. As a result the division does not appear to develop behind solidly organized covering forces which can assure an uninterrupted deployment through coordinated defensive action, even though the numerical infantry strength of the advance guards is usually large, averaging from a third to a half of the infantry of the division.
d. Faults. The frequent use of the advance guard reinforced to make a holding attack and generally deployed on a wide front, renders control difficult and the organization of an effective attack even more difficult. The close-in envelopment so often chosen arises from a desire to get the attack off quickly and from the weakness of the organic artillery of the division. The Japanese teachings are to keep the artillery in a central location so that fire can be maneuvered over most of the front of both holding and enveloping attacks. If done this would restrict the scope of the possible attack directions.
e. Reconnaissance. Map problems and terrain exercises which have been studied show that an insufficient time is allocated for reconnaissance and organization of the attack. In one map problem only 1 1/2 hours elapsed between the decision of the division commander and the jump-off of the so-called coordinated attack. While this is an extreme case, the impression of insufficiency of time for preparation is general.
f. Summary. In summary, the characteristics of the Japanese division in the meeting engagement are:
- Rapid, aggressive offensive action by all elements.
- A tendency to uncoordinated piecemeal action.
- Development behind weakly linked covering forces.
- Frontal attack or restricted close-in envelopments.
- Inadequate artillery support.
- Sacrifice of proper reconnaissance and organization to obtain speed in attack.
- Attack through terrain generally considered to be impossible.
10. ATTACK OF POSITION. a. General. When the enemy has had time to occupy and organize a position, the Japanese commander endeavors to fight the decisive action outside of the organized area by turning the position. This is often attempted by an approach over terrain said to be impassible or under adverse weather conditions. The intention in both cases is to achieve surprise in the direction and time of attack. However, the presence of other Japanese units on the flanks often may limit the possible maneuver area. The technique of such an attack resembles that of the coordinated meeting engagement in the use of the approach march and the development of the situation by the advance elements; it differs in the amount of time necessary for reconnaissance and attack preparations. However, the need for carefully executed attack preparations, according to the Japanese, must not be made the excuse for allowing the enemy undue time to improve his position. As shown in map problems, when a commander encounters a position which has been strengthened during a period of several days, he ordinarily drives in the covering forces and reconnoiters during all or part of one day and launches his main attack the following morning. He appears quite capable of attempting all of this in one day if time is pressing.
b. Development. (1) The hostile position normally will be covered by outposts which will vary in. strength from patrols to a relatively strong force supported by artillery and deployed as an outpost line of resistance. As the Japanese advance guards approach contact with the covering forces, and before the main body comes under long-range artillery fire, the division commander usually orders his column into assembly areas.
(2) It should be noted that going into assembly areas is a phase of the attack of a position not ordinarily present in the meeting engagement. In problems studied these areas are from 2,200 to 4,400 yards from a hostile outpost line and thus 4,000 to 6,000 yards from the hostile artillery. In the typical case of the division advancing in two columns three assembly areas are designated, one for the main attack force, one for the force making the secondary effort, and one for the division reserve. The assembly is covered from positions about 1,100 to 1,600 yards in advance.
11. DRIVING IN COVERING FORCES. a. Procedure. In order to obtain adequate information about the main defensive position, the Japanese division ordinarily first drives in the hostile covering forces and then executes the necessary reconnaissance for the main attack. If these covering forces are weak and do not form a continuous front, the advance guard commander drives them in on his own initiative; otherwise, the division commander organizes the operation under cover of strong artillery support. In the typical case, this attack takes place in the afternoon of one day, and is followed by attack of the main position at daylight the next day
or shortly thereafter. When the opposing forces occupy positions very close together, two nights may be necessary to get the attacking forces and materiel into position.
b. Continuous attack. This procedure of successive attacks, while designated as orthodox in Japanese Combat Regulations, often is replaced in practice by a continuous attack on both outpost and main position. It is not clear when this variation is considered justified, but apparently the deciding factors are whether the artillery can support the attack through both positions without displacement (moving) and whether the time element is pressing. When the continuous attack is made, that on the outpost line becomes a phase of the main attack, and the attacking infantry usually pauses briefly on the captured position, and then continues the assault. In about half of the map problems studied the continuous method was adopted, although there was no apparent need for especial haste in launching the attack.
12. ATTACK ORDER. While the infantry is deploying in assembly area (kaishin haichi) and the advance guard is driving in the covering forces, the division commander, after completion of his plan of attack based on reconnaissance reports, issues his order for the final deployment of the division and the subsequent attack. The order includes familiar elements, except that the infantry in the assault is divided into right and left wings (occasionally into a right wing, left wing, and center) in accordance with the scheme of maneuver.
13.TECHNIQUE OF ATTACK. a. Infantry. (1) The typical disposition of the units in the assault is into wings, with the preponderance of strength in one wing assigned to make the main effort, while the other wing makes the secondary attack. The infantry units, in accordance with the plan of deployment, advance from the assembly areas to their assigned positions along the line of departure, where they make final attack preparations. When the attack is to jump-off about dawn (first light), the advance to the line of departure is made under cover of darkness; if made in daylight, all means are utilized to conceal and protect this movement. In problems, the lines of departure vary from 550 to 2,000 yards from the enemy main position, and the line is chosen so as to be protected from effective small-arms fire. When the attack on the main line of resistance and the outpost line of resistance is continuous, a pause and a realignment may take place along the rear edge of the outpost position which then becomes a phase line in the course of the attack. Attack objectives (terrain features) or attack directions are given the frontline infantry units according to the known details of the enemy position. Normally, the line to be reached by the attack is deep in the zone of the hostile artillery. The hour of attack is usually about 1 or 2 hours after dawn, as the Japanese have little confidence in the ability of their artillery to adjust and fire a preparation at night. In case of an attack entirely in daylight, a minimum of 4 hours is allowed between the time of the attack order and the assault to provide for distribution of the order and for artillery preparation.
(2) In the decisive effort the average frontages of attack are:
Yards Company 225 Battalion 400 to 600 Regiment 1,100
Frontages are 20 to 25 per cent greater for units making the secondary attack.
(3) The division reserve is assembled under cover in the zone of the main effort approximately 1
1/2 to 2 miles from the line of departure.
b. Tanks. When available, tanks are brought up with great secrecy to assault positions. Here they are attached to front-line battalions and jump off at the same time as the front-line infantry. The infantry is warned not to stop if the tanks are destroyed but to continue the advance. Tank missions are the breaching of enemy wire and destruction or neutralization of hostile elements.
c. Artillery. (1) The division artillery frequently is reinforced with light and medium battalions. Its combat organization usually provides for a direct support group of from one to two battalions for each wing without any artillery being held in general support. If a fourth battalion is attached it may be employed as a counter-battery group in a relation similar to general support. Fire missions are varied according to the phases of the proposed action, a typical assignment where there is no reinforcing artillery being the following:
(a) Phase I. Attack of the outpost position. Missions: counter battery by one battalion, direct support fire by two battalions, with special attention given to the troops of the main effort.
(b) Phase II. From the occupation of the outpost line of resistance to the opening of the artillery preparation. Missions: counter battery, harassing, and interdiction fires.
(c) Phase III.The artillery preparation.
1. Duration one to two hours.
2. Subdivisions (approximate).
1/2 hour of fire for adjustment (ranging) in daylight.
1/2 hour for wire-cutting accompanied by slight counter-battery.
1/2 hour of fire on infantry position.
(d) Phase IV. The attack. Mission: direct support fires with particular attention to the main effort.
(2) All the division artillery deploys for the attack of the outpost line of resistance. The artillery positions are pushed forward to within 500 to 800 yards of the infantry line of departure so as to be able to support the attack of the main position without moving. At the time of the attack on the main
position, 1 or 2 artillery companies often are attached to the main effort as accompanying artillery.
(3) The ammunition allowance for the light artillery in an attack of a position is usually 3 to 3 1/2 days of fire (1 day of fire 75-mm equals 300 rounds).
(4) Two to three airplanes normally are attached to the artillery for observation and command purposes.
(5) Implied gunnery methods seem to be elementary, with main reliance on axial ground observation and with observation posts generally close to the guns. The Japanese Combat Regulations imply, however, that the artillery is capable of registering at night and of opening fire promptly at dawn.
d. Antiaircraft artillery. The usual attachment of antiaircraft artillery to a division appears to be a battalion, consisting of three gun companies (and sometimes a searchlight company). Such machine guns as are in this battalion are for its own local defense. In the attack of a position, the gun companies are placed in the zone of the main effort, in initial positions about 2,700 to 3,300 yards from the line of departure of the infantry.
e. Cavalry or reconnaissance. About one platoon is normally attached to each wing for duty as messengers and orderlies. The remainder is divided for flank protection with the bulk on the decisive flank. As the strength of the division cavalry regiment is light, the combat value is not as great as might be expected.
f. Engineers. Engineer missions in the typical case are: maintenance of communications; assistance to the artillery and tanks; wire cutting; and the removal of obstacles.
g. Command posts. The average distances of command posts from the line of departure for the attack of the main positions are:
Yards Infantry regiment 1,100 Artillery regiment 2,700 Division 2,700
h. Destruction of obstacles. The Japanese normally assume there is some wire in front of the hostile position. An attack order therefore includes provisions for cutting the wire in one of the following ways:
(1) By detailed destruction fires by the artillery.
(2) By artillery fire in the most important places, supplemented elsewhere by hand cutting by infantry, tanks, and engineers.
(3) By the artillery cutting the wire imperfectly at all points, with the cutting to be completed in detail by infantry, tanks, and engineers. Where there are several bands of wire, it is normal to make the destruction of the first band the exclusive duty of the infantry and engineers.
i. Medical troops. About one-third of the medical troops are assigned to support each wing; the remainder are in reserve. These detachments set up and operate division collecting (dressing) stations located behind the regimental dressing stations. Locations are from 1,600 to 2,200 yards behind the line of departure. Two field hospitals are set up about 2,500 to 4,000 yards from the line of departure; the division is capable of setting up one additional hospital held initially in reserve.
j. Ammunition supply. The advance section of the transport regiment (senshin shicho) ordinarily opens an infantry ammunition distributing point in rear of each wing as well as one artillery distributing point.
14. ASSAULT. There is little in tactical problems which bears specifically on the conduct of the assault. While the infantry pushes ahead boldly without regard to alignment, and with bayonets fixed, the division commander influences the action by the fire of his artillery and by the division reserve. This reserve may be used to meet a counterattack, to exploit a success, or to cover the flank of a penetrating unit. The division reaches its objective prepared to pass to the pursuit in accordance with plans previously made by the division commander.
15. COMMENTS. a. Characteristics. In their concept of the attack of a position the Japanese show complete disregard of casualties in pressing it to a successful conclusion. Their campaigns initially met with a great measure of success in tropical countries because they had trained extensively in jungle terrain and adapted their technique to capitalize on what their enemies considered hindrances and handicaps. The following characteristics were common to their campaigns:
(1) Careful, meticulous staff work in the detailed planning of the operation, training and equipping of the forces to be used, and in coordinating and carrying out the action.
(2) Great boldnesses, both in the conception of the operation and in execution of its details.
(3) Fearlessness of the enemy and the ground weapons he had at his disposal.
(4) Disregard of casualties in attaining an objective.
(5) Use of surprise and deception.
(6) Refrainment from advancing to the attack before interdiction of all nearby enemy airfields and attainment of air superiority in the area of the attack.
(7) Great speed in infiltration, envelopment, and pursuit.
(8) Willingness to attack through terrain normally considered impassable and in adverse weather conditions.
b. Criticisms. (1) The willingness with which the Japanese commander will order an attack on an outpost simultaneously with the attack on the main position has already been mentioned; this is done
in spite of the prescription in Combat Regulations which indicates that effective reconnaissance can only be obtained after the outposts have been driven in. His shortening of the time allowed for reconnaissance and preparation has in many cases reduced the already slender chances of reaching the final objective.
(2) The deployment of the division is generally along orthodox lines, excepting that the assembly areas are invariably within effective enemy light artillery range.
(3) The plan of maneuver offers nothing of special advantage for the direction of the attack, as it usually culminates in a parallel, frontal, or semi-frontal push executed by the two wings of the division, with one wing--the decisive one--somewhat stronger in infantry and artillery. However, if this form of maneuver is accepted, there is still a weakness in the absence of a decisive massing of force on a decisive point.
(4) Japanese use of artillery is subject to much criticism. The fundamental fault is that there is generally not enough of it. This weakness in artillery may be the result of a lack of appreciation of the need for adequate fire support, or of a feeling that past experience has not demonstrated the need for stronger artillery. The period of daylight fire for adjustment prior to the fire for effect reduces tactical surprise and diminishes the moral effect of the preparation. This unwillingness to fire the preparation unobserved at night would suggest low gunnery efficiency. Also the absence of general support artillery reduces the flexibility of the artillery fires and limits the ability of the division commander to intervene promptly in the action by the use of his artillery. From the picture drawn in the tactical problems, one can feel reasonably sure that the Japanese infantry will jump off, even though their extensive preparations have neither destroyed hostile wire nor neutralized the enemy artillery and machine guns. The detailed workings of the direct support fires are not described in the problems studied; hence, no estimate of their effectiveness can be made other than that implied by the absence of detailed plans for infantry-artillery liaison.
(5) While the detailed administrative plan of the attack does not appear in the problems studied, such establishments as are located on the situation maps are considerably closer to the front line than is considered standard. Lack of depth is characteristic of both the tactical and administrative dispositions of the Japanese division and has its origin in their lack of appreciation of the effect of modern fire power, particularly that of the hostile artillery. A period of contact with a well-equipped enemy may furnish correctives for this tendency.
(6) In general, although the adverse criticisms are numerous, it is not to be assumed that the Japanese will persist long in these errors, if errors they prove to be on the battlefield. The Japanese gifts for adaptation and improvisation can be counted upon to remedy quickly many of the faults in their doctrine.
17b. PURSUIT. a. General. Japanese regulations and tactical doctrines place the normal emphasis on the need for pursuit to reap the full fruits of victory. They also recognize the existence of many deterring elements, such as fatigue of the troops, disorganization, and depletion of supplies. In spite of these, the Japanese commander is urged to pursue relentlessly to avoid the need for another battle against a reorganized and possibly reinforced enemy.
b. Preparation for pursuit. The Japanese commander throughout an engagement plans constantly for the pursuit. The enemy is observed carefully, especially at night, for signs of an intention to withdraw. To determine this intention, the Japanese use ground reconnaissance patrols and spies, and they may use observation aviation if it is available. When these means are inadequate, the commander is urged unhesitatingly to stage a local attack to gain the required information. While he is pushing this reconnaissance, he makes preparation for a possible pursuit. These preparations take the form of alerting certain units for immediate pursuit, of assembling sufficient ammunition for the operation, and of outlining a tentative administrative plan.
c. Types of pursuit. While the quick destruction of the defeated enemy is the object of all pursuit, this cannot always be effected immediately by a single simple maneuver. In seeking to destroy his opponent, the pursuer usually will try to fix him by direct pressure while enveloping or turning one or both flanks. If this maneuver fails, he may try to push the retiring enemy off his line of retreat or into a disadvantageous position where he can be attacked more effectively. In recognition of these differing situations, Japanese writers treat the operation under two types: Type 1, where the enemy is destroyed near the field of battle where he sustained his initial defeat; and Type 2, where the enemy has partially succeeded in extricating himself, and the pursuer must take distant objectives deep in the enemy's rear after resuming semi-march dispositions. In both types, the destruction of the enemy is accomplished by fixing him with direct pressure, while mobile pursuit detachments, moving around the flanks, occupy the critical points along his line of retreat and fall upon his rear.
d. Technique of pursuit. (1) (a) Type (1). This form of pursuit finds its type example in the case of the daylight withdrawal of a hard-pressed enemy. The withdrawal is observed by the attacker, who immediately redoubles the frontal pressure, while available reserves are quickly formed into pursuit detachments which turn the enemy's flank and fall upon his rear. Boundaries between front-line units are readjusted as needed. The destruction of
the enemy thus is accomplished in or near the original field of battle. The detailed action of the separate arms is essentially the same as in type (2), except that distant marches, with a reforming of march columns by the frontal pressure force of the infantry, are not required.
(b) Type (2). This form of pursuit is regarded as the usual one by the Japanese. Most problems studied were of this type, wherein the enemy succeeds wholly or partially in disengaging himself and beginning a withdrawal. The initial withdrawal usually is accomplished under cover of darkness and may not be discovered at once. When the Japanese front line unit commanders find out what is occurring, they renew the attack individually and upon their own initiative in an effort to push through or around the hostile covering forces. As these Japanese units push through the enemy position, reserve units, formed into pursuit detachments, are started around the flanks with objectives deep in the enemy rear. When the Japanese front line infantry units have passed through the zone of resistance of the covering forces, the division commander halts them, organizes and sends forward additional pursuit detachments, and causes the remainder to form march columns to follow in the trace of the pursuit detachments. As this form of pursuit is considered to be usual, the subsequent remarks on the missions of the various arms apply specifically to this type, although they are also applicable with slight modification to Type (1).
(2) Front-line infantry. All units are individually responsible for discovering the hostile intention to withdraw. After such discovery, they drive into the enemy covering forces on their own initiative. In order to get through the enemy covering forces the Japanese prefer to turn the organized localities by maneuver or by infiltration through the gaps. When neither is possible, a quickly organized attack on a narrow front is indicated. As the action of front-line units is decentralized, most of the division artillery is attached to front-line infantry regiments. Tanks are sent in to block the enemy's retreat and to attack his artillery and command posts. To avoid a serious loss of control, the division commander usually indicates a line in rear of the probable enemy covering positions where the troops halt and reform for further pursuit. A part of the frontline infantry is then organized with previously formed pursuit detachments. The bulk of the division reforms into march columns and follows after the pursuit detachments.
(3) Artillery. When the enemy is discovered to be withdrawing, the artillery endeavors to disrupt the enemy's retreat by interdicting (harassing) the important defiles and bottlenecks in the road net. As the front-line infantry penetrates into the covering position, the artillery, attached to infantry units, follows by bounds close behind the advancing troops and concentrates its fire on the resisting enemy infantry. Some artillery is attached to pursuit detachments.
Figure 83. Pursuit formation.
e. Comments. The Japanese pursuit in theory offers little variation from standard practice. Japanese regulations urge the utilization of all available transport, but, in the absence of especially attached motor transport, the division has been incapable of giving the required mobility to the pursuit detachments. The well-known marching power of the Japanese infantry can be counted upon to compensate in a measure for this deficiency in motor transport. The pursuit is a form of operation thoroughly in line with the offensive spirit of the Japanese Army, and the war in China has shown that the Japanese pursue just as vigorously and unhesitatingly as their regulations prescribe. The North China campaign was particularly rich in examples of rapid pursuit. In the advance down the Pinghan and Tsinpu Railways, the Japanese put their pursuit detachments on freight cars and sent them far into Chinese territory, while the main body of the divisions followed partly by rail and partly by marching. Where rail transportation was not available, the Japanese organized special motorized units (kaisoku butai) to give rapidity to their pursuit.
17. RIVER CROSSING. a. General. (1) Japanese river crossing methods are essentially those of other Armies. Success is sought through surprising the defense by concealment of preparations and rapidity of action after the crossing starts. Normal attachments to a division contemplating a river crossing include units of antiaircraft, observation aviation, engineers, artillery, and armored cars.
(2) The advance to the river is made on a broad front and is preceded by advance detachments to drive back enemy patrols from the near bank and to seize existing bridges, bridging materials, and boats. The aviation reconnoiters both banks of the river, while the Engineers conduct a detailed reconnaissance for possible ferry and bridge sites, and for local engineer supplies.
Figure 84. Typical river crossing.
b. Comments. The river crossing methods described are in general so orthodox as to occasion little comment. However, the pooling of all the Engineers into a unit in general support of the crossing is a deviation from the usual method of attaching Engineers to the crossing commanders. The weakness of the division artillery makes extremely difficult the support of an operation on a wide front such as a river crossing. It becomes difficult to allot any artillery to the distant feint, without which there cannot be much deception. The use of the reserve to create false activity, and the strict measures taken to control spies among the civilian population, are further examples of the emphasis placed on secrecy and deception in all Japanese operations.
18. NIGHT ATTACK. a. General. The Japanese Army has a strong partiality for the night attack. This form of combat favors the bayonet fighting stressed in infantry training and tends to cover the weaknesses in artillery and cooperation of the combined arms which have characterized the Japanese Army. The Japanese are further encouraged in their faith in night attacks by successful experiences in the Russo-Japanese War and subsequent operations in China and during the early part of the present war. The night attack sometimes is referred to as "a specialty of the Japanese Army" and as "a traditional Japanese method."
b. Advantages and disadvantages. The advantages attributed to the night attack are avoidance of losses, concealment of movement, and rapidity in closing with the enemy. Disadvantages conceded are loss of cooperation between units, loss of unified direction, a greater chance of mistakes, and confusion. The Japanese believe trained troops can overcome these disadvantages and succeed even when opposed by superior numbers. Thus, in justifying a night attack, there is a tendency to reason, "The enemy is too strongly organized or too numerous for us to hope to defeat him in daylight; only by a night attack have we any possible chance to defeat him and accomplish our mission."
c. Occasions for night attacks. (1) Night attacks are considered appropriate for units varying in size from company to division. Orthodox situations calling for night attacks are the following:
(a) A large unit (division) wishing to extend or complete a success during a daylight engagement may continue the attack at night.
(b) Large units (divisions) may use a part of their force to seize by surprise points needed to assist the attack of the following day.
(c)Local night attacks may be used to distract or mislead the enemy and to conceal Japanese activity elsewhere (for example, a night withdrawal).
(2) These three occasions mentioned above are referred to as orthodox since they are the ones described in Japanese Combat Regulations. In practice the night attack has been used in the following additional situations:
(a) By a large unit to prevent a hostile night withdrawal or to complete the defeat of the enemy before he could be reinforced.
(b) When superior fire power of the enemy prevented the reaching of attack objective in daylight.
d. Hour of attack. Combat Regulations indicate that the period just after dark and just before daylight are desirable hours of attack. In 4 peacetime exercises the hours were, dusk, 2400, 0030, and 0200. The considerations involved in choosing these hours were that the engineers need at least 2 hours to cut paths in the hostile wire prior to the attack and that the objectives should be reached shortly before dawn to allow a coordinated renewal of the attack from the new line of departure a little after daylight.
e. Reconnaissance. Regulations insist on the importance of a thorough knowledge of the terrain on the part of all commanders involved in night
attacks. Japanese commentators stress the need of detailed information as to the location of enemy strong points, machine guns, obstacles, searchlights, etc. In observed peacetime practice, however, the time allotted for reconnaissance was usually quite short. Concrete examples noted were:
(1) A regimental commander, hard pressed in a meeting engagement, decided at 1530 on a night attack at dusk, less than 4 hours later.
(2) In two separate map situations, two brigade commanders decided at 1600 and 1700, respectively, while in the course of attacking a prepared position, to make a night attack shortly after dusk of the same day. These decisions are believed to have been made at such time and under such conditions as would preclude much real reconnaissance.
f. Objectives. (1) "The objectives of a night attack are limited and are shallow in comparison to those of daylight attacks." (Japanese Combat Regulations.) Each subordinate unit receives terrain objectives as clearly defined as possible. Villages are avoided, since they are difficult to attack at night.
(2) Objectives assigned are often ambitious. The boundaries of tactical localities assigned frequently are not clearly defined features which guarantee against errors in the dark. The final objective is usually the rear edge of a position about 1,100 yards deep. Apparently about half of this is believed enough for the first bound. It will be seen in the discussion of attack dispositions that this depth of objective requires a night passage of lines on the first objective. Advance infiltration units usually precede the main attack to neutralize the enemy.
g. Conduct of attack. (1) Infantry. (a) The infantry of a night attack usually is disposed in two assault echelons and a reserve. If the objective is shallow, one assault echelon may suffice. In the normal situation, however, a first wave rushes forward and seizes the line which constitutes the first objective; the second wave passes through the first and moves on to the second objective. This second wave also has the missions of repulsing counterattacks and destroying enemy searchlights. The relative strengths of the first and second waves depend on the relative strengths of the first and second positions. In general, a force of from one or two platoons, commanded by an officer, is given the mission of attacking and occupying a definite enemy strong-point. A battalion generally attacks in a 450 to 550 yard sector, with 2 rifle companies in the first wave, 2 companies less a platoon in the second wave, and a platoon in battalion reserve. The battalion is expected to reach and occupy 2 objectives, the more distant being some 1,100 yards from the jump-off line. Where the rear objective is more distant than this, or the going is more difficult, 2 battalions may attack in column, the rear battalion being responsible for the taking of the second objective. The following is a schematic representation of a typical attack formation.
Figure 85. Battalion in night attack.
(b) In the foregoing dispositions, companies 1 and 2 are in a line of platoons, each platoon being in a line of squad columns; companies 3 and 4 are about 100 yards behind the leading companies in a line of platoons, each platoon in a column of squads. Exact intervals between platoons are not known, but the frontage of a company is relatively narrow, about 100 to 175 yards. The battalion reserve follows the preceding company at about 50 yards. While the Japanese recognize that this dense formation is highly vulnerable to fire, they consider it justified by ease of control and effectiveness of shock action.
(c)The infantry assault is with the bayonet without firing. Battalion guns may be used against searchlights and obstacles, and machine guns will participate in protective fires.
(2) Wire-cutting, gas, and smoke. Engineers are attached to the assault battalions for cutting lanes through the enemy wire. This cutting starts secretly after dark, about 11/2 to 3 hours before the attack. About 3 lanes per battalion apparently are considered sufficient. If gassed areas are to be encountered decontaminating detachments precede the assault; chemical detachments for laying smoke screens also may be pushed forward if the enemy searchlights are troublesome.
(3) Artillery. (a) Night attacks are classified as "kishu" and "kyoshu." The first is translated as "attack by surprise" and the second "attack by force." Attack by surprise (kishu) is characterized by an infantry rush with bayonet, but without a preparation or accompanying fires by the artillery or infantry weapons. Attack by force (kyoshu) implies coordinated accompanying fires and possibly a preparation. The attack of the first objective is an attack by surprise (kishu), unless the enemy is thought to be expecting a night attack; the attack of the second objective is an attack by force (kyoshu).
(b) A battalion of artillery normally supports an infantry regiment. The artillery commander, after conference with the commanding officer of the infantry, prepares fires to be available on call during
the attack. The usual method of call is by rocket. In preparing fires, special consideration is given to possible enemy counterattacks. The artillery may be required to cut wire, but this is costly in ammunition.
(4) Maintenance of direction. Maintenance of direction at night, being difficult, requires special measures. Devices used are--
(a) Compass bearing.
(b) Road markers, such as white stakes, strips of paper, lines of chalk or flour, and ropes.
(e) Shells fired for direction of artillery.
(f) Rear lights giving direction by alignment.
(g) Company commanders wearing two crossed strips of white cloth on their backs; lieutenants, a single strip.
(5) Comments. (1) An enemy facing the Japanese Army may expect to receive frequent attacks at night, at least until this form of combat proves definitely unprofitable. Factors favoring the success of such attacks are:
(a) Detailed training in night marches, maneuvers, and attack.
(b) Special emphasis placed on use of the bayonet and hand-to-hand fighting.
(c) Emphasis placed on the element of surprise in the execution of night attacks.
(d) Constant use of infiltration, outflanking movements, and attacks from the rear in country where cover is dense.
(2) It is believed that the following defects will militate against the success of the Japanese night attacks in the face of an alert enemy:
(a) An over-readiness to attack at night in the hope of retrieving a check received in daylight fighting.
(b) Insufficiency of time allowed for reconnaissance, planning, and distribution of orders.
(c) Over-ambitious objectives.
(d) Mass attack formations highly vulnerable to enemy fire.
(e) Reserve units following on the heels of assault waves where they would soon be lost to control of the commander.
(f) Inadequacy of artillery support to neutralize enemy automatic weapons and to cover the operation with protective fires.
(g) An attempt to execute a night passage of lines in the course of an attack.
(3) Against an enemy who has not been determined to hold at all cost, the night attack has had and may be expected to have many successful applications. However, against a vigilant enemy, strong in automatic weapons, it has proved costly to the Japanese.
Section III. DEFENSIVE
1. GENERAL. a. Japanese attitude. The defensive form of combat generally has been distasteful to the Japanese, and they have been very reluctant to admit that the Imperial Army would ever be forced to engage in this form of combat. So pronounced has been their dislike for the defensive that tactical problems illustrating this type of combat are extremely rare.
b. Object. The object of the defensive is to inflict on the superior hostile forces such losses by fire power, disposed appropriately on the terrain and behind man-made defensive works, that the initial disparity of forces becomes equalized to the point of authorizing a passage eventually to the offensive.
c. Doctrine. The old Combat Regulations (Sento Koyo), superseded in November, 1938, based discussion of the defensive on the active defense. The newer regulation (Sakusen Yomurei) takes the passive defense, assumed in the presence of overwhelmingly superior forces, as the typical case, of which the active defense is a variant calling for special discussion. This latter viewpoint is definitely contrary to former practice where a return to the offensive is always present in the plans for the defense, even though the initial dispositions are not those of an active defense in the true tactical sense of the word. This indicates a change in official emphasis, but probably means no real change in the practice of the defense, since in actual combat and in illustrative problems there is always present the characteristics of active defense.
2. DEFENSE OF A POSITION. a. Selection of the position. The qualities sought for the main battle position (observation, protected flanks, fields of fire, covered lines of communications, obstacles, etc.) are those standard in all schools of military doctrine. In accordance with the current trend, the Japanese emphasize the importance of antitank obstacles across the front and flanks of their position. In the presence of an enemy who may use gas, the main line of resistance will avoid depressions where it is likely to accumulate. The importance of cover and concealment is fully recognized. Reconnaissance for the position is made by the division commander, assisted by his artillery and engineer commanders as well as other appropriate staff officers.
b. Occupation of the position. When the general outline of the position has been determined, the division commander directs the subordinate elements of his command to their respective defense areas where they deploy directly upon the position which they are to occupy. The division commander directs his cavalry (often reinforced by some infantry) to cover the deployment and organization of the position. This force takes position far enough in advance of the area to be organized to keep hostile artillery fire off the main line of
(a) Determination of the probable direction of hostile attack.
(b) The probable direction of a division counterattack or counteroffensive.
(c) Antitank measures.
(d) The assignment of troops within the defensive area.
(e) The use of artillery including antiaircraft.
(f) The composition and location of the division reserve.
(g) The use of tanks.
(h) Communications and liaison.
The completeness of the reconnaissance is dependent on the time available. He then issues his defense order.
c. Organization of the position. (1) The defense is based on a main position (shujinchitai) which is held to the last extremity. The division commander normally divides the defensive position into right and left sectors (chiku) the defense of which he assigns to his two senior infantry commanders. In cases where the front is unusually broad, or a counter-offensive is planned, he may add a center sector. The Infantry is disposed along the main line of resistance by units of battalions, with frontages determined by the terrain and mission. When a broad defense is adopted, battalion centers of resistance are organized for an all-round, independent defense, in which the lateral intervals can only be partially covered by fire. In this form of defense, reserve units, kept as large as possible, are held mobile to attack hostile elements which filter through. Battalion frontages in the broad defense along the main line of resistance may approach 3,000 yards, while the normal defense frontages average from 800 to 2,000 yards.
(2) Support and local reserve units are deployed behind the front line infantry to give the position a depth of 700 to 1,500 yards. Throughout this zone automatic and antitank weapons are echeloned in depth. Usually heavy machine guns are found deployed along the support position, from which they attempt to cover the front with interlocking fires (criss-cross fires).
3. THE OUTPOST POSITION a. The outpost position (Keikai Jinchi) is indicated by the division defense order and is garrisoned by troops dispatched by the sector commanders. The order may specify the strength of the garrison, its mission, and manner of withdrawal. Troops on the outpost line of resistance normally pass to division reserve when relieved The outpost line of resistance is generally from 1,500 to 3,000 yards in front of the main line of resistance, so as to be within supporting range of light artillery. Combat Regulations tend to recommend the shorter distance so as to obtain the fire support of machine guns from the main line of resistance. However, in observed practice, the Japanese seem to attach little importance to the uncertain support of long-range machine gun fire.
b. The normal missions of the outpost line of resistance are to obtain enemy information by observation and patrolling, to cover the main line of resistance and prevent its surprise to delay the hostile attack on the main line of resistance, and to act as an advance defensive position (Zenshin Jinchi). Missions (1) and (2) are the minimum case, where the outpost line of resistance is not much more than a line for observation and reconnaissance with little defense strength. Missions (3) and (4), frequently present in observed practice, imply a considerable increase in defensive means approaching that of a true advanced defensive position.
c. The troops assigned to garrison the outpost line of resistance, while variable in strength with the mission assigned, are kept to a minimum. For the front of a division, 1 to 2 battalions of infantry were normal in the problems consulted. Comments on these problems indicate that about 2,000 yards for the infantry company is considered the absolute maximum extension consonant with the retention of any sort of control by the unit commander. With the usual weak allotment of troops, it is impossible to hold the line continuously. Instead, important points are occupied in some strength, while the intervals are covered by observation and fire as far as possible. The Japanese do not expect to be able to organize a continuous system of infantry and artillery fires in front of the outpost line of resistance. With the help of attached engineers, the infantry strengthens the outpost position by defensive works to the extent permitted in the time available. In the case of the defense on a very wide front the outpost line of resistance is reduced to a line of observers, or may even be dispensed with entirely.
4. ADVANCED DEFENSIVE POSITIONS. a. The division commander at times may order the occupation and organization of an advanced defensive position (Zenshin Jinchi) in the zone between the outpost line of resistance and the main battle position. The purpose of such a position is to prevent as long as possible the occupation of critical points of terrain by hostile forces near the main defensive zone, to delay the enemy preparations for the attack, and to induce the enemy to launch his attack in a false direction which will expose his flan. The organization of a formal advance defensive position is not standard Japanese practice, although the assignment of such a mission to the outpost position is not uncommon. Typical cases where the advanced positions have been organized are: (1) where in order to obtain observation the outpost line of resistance has been pushed well forward, leaving an important ridge in the foreground of the main battle position ungarrisoned; and (2) where an oblique position is organized between the outpost position and the main battle position, with one flank resting on the outpost line of resistance while the other rests on the main line of resistance, thus inducing the enemy to expose a flank.
b. The garrison of the advance position may come from the troops assigned in the outpost position
or from those of the main battle position. reinforced by machine guns and antitank weapons. Artillery elements may be assigned support missions. The delicacy of withdrawing this force is fully appreciated by the Japanese, and the division commander is cautioned to issue clear and simple missions to this force and to specify the time and manner of withdrawal.
c. In cases where the division commander elects not to organize an advance position, the zone between the outpost and the main battle position is covered by observers sent forward by the front line infantry battalions. These troops patrol the foreground, cooperate with those of the outpost line of resistance, and execute local reconnaissance.
5. RESERVES. a. Reserves are held out by all units from the company upward for the purpose of executing counterattacks. The division reserve generally varies in size from 1 to 3 battalions. Its position is initially from 5,500 to 6,500 yards in rear of the main line of resistance, in a sheltered position conveniently situated with respect to the probable counterattack of the division. Tanks often will be attached to this force.
Motor transportation generally is not attached to the reserve because of the paucity of organic motor transport in the division.
b. When the division commander has planned an active defense, the general reserve as a rule will not exceed a third of the infantry strength, since front line units themselves are expected to return to the offensive at the earliest opportunity.
6. ARTILLERY. The artillery is disposed in depth behind the main line of resistance so as to be able to mass its fire in support of the main position in the area of the hostile probable main effort. One or two artillery companies may be initially in forward positions to support the outpost positions or an advanced defensive position. Artillery positions generally are echeloned through a zone about 2,500 yards in depth, extending to the rear from a line about 1,700 to 2,200 yards behind the main line of resistance. Ground observation is not considered effective under normal conditions for ranges over 5,500 yards.
7. COMMAND POSTS. a. General. Command posts generally are established in well sheltered positions in rear of the main line of resistance; that of the division is usually located at a distance of about 5,500 yards, that of the infantry group at about 2,700 yards, and that of the infantry regiment at about 1,300 yards in rear of the main line of resistance.
b. Organization of the ground. (1) In the early phases of the reconnaissance of the position, the division commander gives initial instructions to his engineer regarding the supplying of entrenching tools, material, and equipment. The defense order indicates the priority of work, a typical one being the following:
(a) Principal points on the main line of resistance.
(b) Fields of fire and observation posts of the main line of resistance.
(c) Obstacles in front of the main line of resistance.
(d) Communications, trenches, and personnel shelters.
(2) In tactical problems it is seldom assumed that there is time available for elaborate field works. The division usually has from about 3 hours to a half day to complete its organization of the ground. Three hours is considered the minimum required to organize a rudimentary system of trenches and obstacles along the main line of resistance. The time-work unit in engineering calculations is the 12-man squad which is considered capable of digging about 25 yards of standing fire trench in a little over 3 hours. In situations in which the use of gas by the enemy is expected, the division commander will order the distribution of protective materials at suitable points throughout the area. Stress is laid on camouflage and the construction of dummy field works, the completeness of which is dependent upon the time available. A typical plan followed by the Japanese in the construction of the field works of a company position on the main line of resistance is illustrated in figures 86, 87, and 88.
Conduct of the defense. (a) Advanced elements. As the enemy approaches the position, he will encounter first the advanced elements of the defense (the outpost line of resistance or advanced defensive position). These forward elements conduct themselves in accordance with their mission which normally directs their withdrawal into division reserve before becoming seriously engaged. Artillery companies in forward positions delay the hostile advance, cover the withdrawal of the infantry, and then fall back to prepared positions in the artillery zone where they revert to the control of their organic commander. The cavalry which has withdrawn to the flank, while maintaining contact with the advance positions, will carry out its normal missions.
(b) Defense of the main line of resistance. As the hostile infantry forms up for the attack on the main line of resistance, the defensive artillery brings down its counter preparations fires. Tanks may be sent forward, covered by artillery, to upset the preparations of the enemy. As the hostile attack enters the zone of infantry fires, the sector commanders conduct the defense of their sectors, first by fire, then by the bayonet in front of their entrenchments. Commanders of all units counterattack unhesitatingly as the integrity of their positions becomes threatened by the hostile attack. The artillery assists the close-in defense by standing barrages and concentrations brought down within the defensive position.
(c) The counterattack or counteroffensive. The division commander is constantly on the alert to determine the proper time for the division counterattack
or counteroffensive. The favorable moment will generally be at the time the hostile attack has been stalled; when the enemy has blundered into an unfavorable position; when a favorable opportunity has been created by a successful local counterattack; and when the enemy pauses to reorganize or consolidate his position. The plan for a return to the offensive will be made tentatively well in advance of the occurrence of the opportunity. The direction of the counterattack generally will be aimed at an envelopment; however, at time, the situation may compel a purely frontal attack. The mass of artillery, and tanks if present, will support the counterattack or counteroffensive. The division commander may directly control the counteroffensive, or he may delegate control to a sector commander.
8. COMMENTS. a. Aggressive character. Since the defensive in Japanese regulations and military writing is branded as a negative form of combat, un-Japanese in essence and spirit, it has been very difficult to write a tactical problem for which officers were willing to advocate a defensive solution. In problems studied, the basic decision to defend already had been made by the division commander, a school device to control the offensive elan of the student officers. Even when thus forced on
Note. After approximately 6 hours of work the individual firing trenches within a squad position will be connected, forming a single line.
Figure 86. A company position after approximately 2 hours of work.
Note. Squad positions will be enlarged standing trenches. THe communication trenches will be deep enough for crawling, and the shelters will be of light construction, accommodating 6 men. Only the machine gun shelters will be built to resist 150-mm howitzer fire. The wire entanglements beyond the front-lines will be 8 meters in depth.
Figure 87. The company position after approximately a week of construction time (56 hours).
Figure 88. A company position after approximately 4 weeks of construction time.
the defensive. Japanese officers have the return to the offensive always uppermost in their minds and are quick to launch counterattacks, large and small, coordinated and uncoordinated, on the slightest provocation. On the maneuver ground, troops are always ready to abandon their prearranged system of infantry fires to meet the attacker with the bayonet in front of their trenches. The defects of a defense so conducted are glaring to the occidental student of tactics, but its positive and aggressive character has virtues which will, on occasions, upset a careless or overconfident attacker.
b. Other characteristics. In spite of the usual instruction issued relative to the need of echelonment in depth of the defense, there is an apparent tendency to concentrate a disproportionate strength in the front line. This is especially true of the special weapons (machine guns, battalion guns, etc.). The appearance of the "broad defense" in Combat Regulations appears to be a recognition of modern infantry, as well as an official corrective to the often remarked Japanese tendency to a should-to-shoulder disposition of units both on the attack and defense.
1. THE WITHDRAWAL. a. General. There is little military literature obtainable to elaborate on the bare substance of the provisions of the Japanese Regulations governing the withdrawal. In general, the method of withdrawal appears to be standard. It is notable, however, the usual strong insistence on the dangers of a daylight withdrawal is not in regulations. No information has been obtained as to when the Japanese commander considers a withdrawal required or justified since, in the cases studied, the withdrawal was executed on army order and was not considered as imposed by the enemy.
Section IV. RETROGRADE MOVEMENTS
b. Preparations for the withdrawal. The division commander, in anticipation of a withdrawal, first attempts to clear his rear area of supply troops and installations, improves the roads which he expects to use, and orders preparations far demolitions to delay the enemy follow-up. All preparations are made with the utmost secrecy while preserving a bold front.
c. Daylight conduct of the withdrawal. (1) Local covering forces. The breaking of contact of the front line infantry is done under the protection of local covering forces, disposed from 1,500 to 2,000 yards behind the firing line. These troops are obtained from battalion, regiment, or other reserves not committed to the front line fighting. The position occupied is, when possible, to the flank of the line of retreat on commanding ground permitting overhead fire in support of the retiring troops. The local covering forces give support by fire and, on occasion, may execute local counterattacks to aid in disengaging the front line infantry. About the equivalent of one regimental sector in open warfare appears to be an average strength for the local covering forces in the problems consulted.
(2) General covering force (Shujo Jinchitai). In addition to these local detachments, the division commander organizes a general covering force behind which he reforms the major elements of his command. The division reserve is usually the principal component of this covering force which, in principle, is made up of the freshest troops at the disposal of the commander. The bulk of the division artillery withdraws and deploys behind this covering position to protect the withdrawal. The Japanese
try to place the covering position at an oblique angle to the axis of retreat and from 3,000 to 5,000 yards in rear of the front line. The division command post is set up behind the covering position for the purpose of controlling the withdrawal and organizing the subsequent retirement for which the troops on the covering position eventually become the rear guard.
(3) Execution of withdrawal. Protected by the covering forces, the front line infantry withdraws straight to the rear assisted by support units in the second echelon. The Japanese feel that it is desirable for all front line units to pull back simultaneously, but often some must hold on longer than others. The division artillery, the bulk of which already has retired to the general covering position, supports the withdrawal. In some sectors, a sudden local counterattack may be warranted in order to create a favorable situation for the withdrawal. Retreating units reform progressively, arriving by many small columns in the general assembly area behind the general covering position. Here, division march columns are formed and directed toward the final terrain objective of the withdrawal. The engineers execute demolitions to retard the enemy, while columns move off covered by a rear guard. The cavalry and aviation reconnoiter for turning movements around the flanks by pursuit detachments. The aviation may be called upon to attack ground troops which are endangering the success of the withdrawal.
d. Night conduct of withdrawal. (1) General. The night withdrawal differs from that in daylight in the following important respects:
a. The local covering mission is performed by a "shell" of small detachments left in position on the front line throughout most of the hours of darkness.
b. Retiring units reassemble and form march columns nearer the front line than is the case in daylight.
c. A general covering position is ordinarily not organized. Detailed preparation in daylight is necessary prior to a night withdrawal. This includes a designation and marking of roads to be used by retiring units, as well as the usual clearing of the rear area. Secrecy is essential throughout to conceal the intention to withdraw.
(2) "Shell" The breaking of contact by the front line infantry is done under the cover of a thin line of infantry detachments, strong in machine guns and supported by a small amount of artillery. This "shell" simulates the usual sector activity throughout the night to deceive the enemy and, if attacked, sacrifices itself in place to protect the retirement. Its time of withdrawal, usually about daylight, is set by the division commander. The mission of the "shell" may be facilitated by local attacks executed early in the night by front line detachments prior to their withdrawal. Normally no general covering force is needed to supplement the "shell." An exception is the case where the "shell", left in place until dawn, requires protection to get away without undue losses.
In such a case, a small general covering force, strong in cavalry and mobile troops, may be organized for the. benefit of the "shell."
(3) Execution of withdrawal. The behavior of the front line units is essentially the same as in daylight. They reform progressively as they retire, assembly areas being somewhat nearer the front line than in daylight. One or two companies of artillery remain until nearly dawn to support the "shell" and carry out normal activity.
e. Comment. Japanese procedure in the withdrawal is generally orthodox. The absence of the customary injunctions against the daylight withdrawal is symptomatic of the Japanese under-estimation of the effects of modern fire power and aerial attack. However, it is unwarranted to assume that, in practice, they will not try to avoid daylight withdrawals when the situation permits.
2. THE DELAYING ACTION. (JIKYUSEN). a. General characteristics. (1) The Japanese do not recognize the delaying action as a separate and distinct form of military operation but include it in the broader term, "jikyusen" (holding-out-combat). The expression is used to cover, in addition to pure delay, a number of types of operations characterized by a desire to avoid a fight to a finish, but in which the idea of delay is somewhat remote. Thus, in addition to the typical delay situations, such as the action of rear guards and covering forces, the Japanese treat under "jikyusen" demonstrations, reconnaissances in force, and night attacks designed to cover a withdrawal. In the subsequent discussion, an effort is made to disregard the elements not bearing directly on delay which the Japanese inject into the treatment of "jikyusen."
(2) The usual purpose of delaying action is to gain time to contain or to divert a superior enemy while avoiding decisive combat. "Although these ends are frequently achieved by defensive action, there are occasions when the mission can be accomplished only by offensive action." The preceding sentence is a literal translation from the Sakusen Yomurei. Elsewhere, the same regulation urges that even when defensive measures are initially better adapted to the situation, the commander must always be ready to take advantage of an opportunity for offensive action. However, when offensive action is indicated, in order to avoid becoming deeply engaged, the division commander designates limited objectives and rigidly controls the number of troops committed to action. In comparison to the meeting engagement, fronts of deployment are wide in such an offensive action.
(3) Mobile troops, well equipped with automatic weapons and artillery, are best adapted to delaying actions. The infantry fire fight generally takes place at long ranges as the engagement is broken off when the enemy draws near. Frontages are wide, and the breadth is obtained by increasing the intervals between occupied key positions. Reserves are kept large to cover withdrawals, to give continuity to
the resistance of the delaying force, and to provide troops for such limited offensive actions as the commander may undertake.
b. Choice of a delaying position. While the situation may force the commander to seek the required delay on a single position, such a disposition creates a danger of becoming involved in a fight to the finish or in a costly withdrawal at close range from the enemy. It is thus preferable to delay on successive positions separated by about two to three miles. A delaying position is chosen for its observation, distant fields of fire, and covered routes of withdrawal.
c. Conduct of the delaying action. (1) When the decision has been reached to delay an advancing enemy, the division commander sends out his cavalry to establish and maintain contact and initiate the delaying action within limits of its combat capacity. He then selects the position or positions upon which he expects to gain the required time for the accomplishment of his mission. He often will send forward an infantry detachment of from 2 companies to a battalion to occupy an advanced position ahead of the first delaying position. Such an advanced position is located within range of artillery support from the delaying position in accordance with the principles for choosing an outpost line of resistance. These forward troops assist the cavalry, as the latter falls back to the flanks of the delaying position, and impose some loss of time on the advancing enemy.
(2) The enemy is taken under fire by the division artillery at extreme ranges. Artillery positions are close behind the infantry, and are grouped together for ease in fire direction in the belief that there is little to fear initially from the hostile counter-battery. Eventually, the infantry machine guns join in the fire fight as the enemy comes within range.
(3) The division commander makes every effort to hold out a large reserve. In cases noted, this amounted to from a third to a half of his infantry and a battalion of artillery. The main purpose of this large reserve is not to counterattack (although some of it on occasion may engage in local offensive action) but to reconnoiter, prepare, and occupy the next delaying position from which it covers the withdrawal of the troops of the first position. The Japanese thus contemplate, in effect, delay on successive positions occupied simultaneously, although this form of action is implied rather than clearly defined.
(4) The engineers of the division find their principal missions in road maintenance, route marking, and the preparation and execution of demolitions. The last are carefully planned to cover the flanks and routes of direct approach to the delaying positions.
(5) As in other forms of combat, the Japanese count heavily on measures of deception to assist in accomplishing the delaying mission. Devices used to create this deception are: dummy engineer works; demonstrations; economy of force in wooded and covered areas while strength is displayed in open terrain; roving artillery; proclamations; propaganda. All these measures aim to create an impression of strength which will cause the enemy to adopt a cautious attitude toward the delaying force. In spite of the fact that such measures impose fatigue on the troops and, in extreme cases may lead to a serious dispersion of effort, the Japanese feel that their use is justified.
d. Withdrawal. The troops on the delaying position retire on order of the division commander while the enemy is still at a distance, unless the mission specifically required a long delay on a single position. When the hostile infantry gets within 1,000 yards of the position it is considered time to go, and the troops on the next delaying position cover the withdrawal. Detachments left in the zone between the positions effect intermediate delay. When it has not been possible to prepare and man a second position, the division commander tries to put off his withdrawal until nightfall.
e. Comments. (1) As a defensive form of combat the delaying action does not appeal to the Japanese soldier who thinks first and last of fixing bayonets and moving forward. Influenced by the strength and weakness of this psychology, the Japanese commander often will choose offensive action when the defensive is better suited to the immediate situation. It has been noted that a little fresh encouragement has been given in the new Combat Regulations to the use of offensive action to obtain delay, an encouragement of which Japanese commanders can be expected to take full advantage in order to seek delay through attack. It is felt that this over-aggressiveness may ill serve the usual purposes of delay.
(2) The injunction to hold out a large reserve does not agree with the usual teachings on delay. A reserve suggests the intention to counterattack, whereas a delaying position usually is abandoned before the enemy has come within counterattacking range. In the practice of map problems, this large reserve was always used to occupy a rear delaying position, so that the operation became, in effect, a delay on successive positions simultaneously occupied. Thus, the requirement of holding out a large reserve, in spite of its apparent contradiction, becomes reconciled with tactical orthodoxy.
(3) The Japanese dislike for using their light artillery at long ranges tends to keep successive delaying positions relatively close together (3,000-4,000 yards). It is generally considered that 5,500 yards is the extreme limit of effective terrestrial observation, and it is rare to assign missions beyond that range. Japanese artillery has had little experience in fire with air observation.
(4) It is reasonable to suppose that the Japanese have learned the latest methods of withdrawal as employed by modern armies which place great emphasis on the use of tanks, mobile artillery, motorized infantry, mines, tank traps, aircraft, and a new concept of distance.
Section V. EMPLOYMENT OF TANKS AND MECHANIZED UNITS
1. GENERAL. a. Background. As a result of experiences in the Manchurian Incident, the war in China, and the clash with the Russians at Changkufeng, the Japanese Army has acquired a lively appreciation of the value of mechanization. Much thought was given to the proper use of this new weapon in the light of the experiences of the Japanese and German Armies. A distinguishing feature was the early modification, extension, and detailed expatiation on the paragraphs devoted to the use of tanks and mechanized units in combat regulations. However, the new changes in regulations, while giving additional space to mechanization, treat the subject with broad generalities which leave considerable doubt as to whether the Japanese have worked out many of the practical details of such highly involved questions as infantry-tank-artillery liaison, control by higher commanders, and logistics of mechanized forces.
b. Estimated strength. (1) At the outbreak of the present war, the known mechanized strength of the Japanese Army consisted of at least 4 tank regiments. While the wartime expansion of tank units is not definitely known, it is believed that there are now additional tank regiments. The reliance on cooperation with the infantry may explain the large number of "Independent" armored units, which can be attached to other formations as and when required. The lack, or failure, to identify artillery, infantry, etc., with the Tank Group also may be explained by this policy, and this formation may, in fact, be more of the Army Tank Brigade type than of the armored division. This view again is borne out to some extent by Japanese teaching, and it is thought that the Tank Group may be employed in conjunction with infantry formations, working in close cooperation with infantry divisions, rather than fulfilling the role of an armored division, which would be to destroy enemy armored formations. It is believed, however, that there are at least 2 armored divisions in Manchuria at the present time.
(2) Weight for weight, the speeds of Japanese tanks do not compare unfavorably with those of other Armies, but it is considered that these speeds drop rather more appreciably across country than do those of Allied tanks. The Japanese tanks are bulkier for their weight since their armor basis is smaller. This can be accounted for by the fact that the Japanese regard their tanks as infantry support weapons, and therefore they rely on the infantry to neutralize the enemy anti-tank weapons.
c. Tactics. Our very limited experience with Japanese tank tactics in Burma and the South West Pacific Area leads to the conclusion that the Japanese regard the tank primarily as a close support weapon for the infantry. Only on one occasion did a small tank versus tank action develop; even then the Japanese tanks are believed to have been surprised during a reconnaissance, and not to have been seeking the armored battle in which they were so badly out-fought. There is little doubt, however, that the Japanese have carefully studied the tactical trends of tank warfare in Europe, and, while industrial limitations make the general employment by the Japanese of large tank organizations unlikely, should they fight in suitable terrain, they reasonably may be expected to employ armor at least as a spearhead to infantry enveloping attacks. Should the nature of the ground permit, the Japanese have, in the tank, an ideal weapon for exploiting their favorite maneuver of a wide and rapid encircling movement which cuts the enemy's lines of communication and generally disorganizes his rear areas. With the Battle of France before them, it is unlikely that they would neglect the advantages gained by the use of armor in this, their favorite offensive maneuver.
2. TRAINING. Japanese tank troops are highly trained in night fighting, and in fighting under extremes of weather. They are obsessed with the value of the attack, and crews will not hesitate to leave their tanks to fight on foot when pressed or in coming up against manned obstacles. Japanese tank training stresses the need for: (1) rapid decisions; (2) rapid mobility; (3) rapid concentration of fire; (4) concealment of intentions; and (5) supply and repair. Frequent practice is given in maneuvers over varied ground; in developing close cooperation within the tank between driver and gunner; and in bringing accurate fire to bear in the shortest possible time. In combat training successive stages are the advance, deployment, attack, mopping-up, and pursuit.
3. TANKS WITH THE DIVISION. a. Offensive. (1) The tanks with a division are normally used as accompanying tanks attached to the infantry units making the principal attack. Prior to the attack such tanks are brought up secretly to assembly positions about 3 miles behind the line of departure. Here final reconnaissance and attack preparations are completed. Tank commanders confer with the infantry regimental and battalion commanders to whom they are to be attached as well as with the artillery which is to support the attack. Topics for conference and decision are: tank objectives and the hour of attack; tank jump-off positions, routes to the jump-off position and the subsequent zone of advance; type of artillery support desired and its coordination with the advance of the tanks; plan for meeting a counterattack by hostile tanks; signal communications between infantry, tanks, and artillery. On the night preceding the attack, the tanks move to jump-off positions under cover of the noise of artillery firing and low-flying airplanes. Attack formations aim at obtaining the effect of mass by disposing the tanks in several waves across the front of the infantry unit to which they are attached. The tanks move forward, followed closely by the infantry and supported by the artillery which neutralizes enemy antitank weapons by fire and smoke. Tank objectives
are: obstacles blocking the advance of the infantry; the enemy automatic weapons left unneutralized by the artillery; and eventually, the hostile artillery and command system. The infantry must stick close to the tanks; if the latter get too far ahead, they may have to turn around and rejoin the infantry.
(2) The foregoing discussion applies particularly to the attack of a position where the need for tanks is especially acute. In the meeting engagement, the tactics of the tanks are in general the same, except that preparations and liaison arrangements are not so detailed, and the attack moves more rapidly. Also, in a favorable situation, the division commander, prior to the main attack, may send out all or part of his tanks ahead of the advance guard to upset the hostile deployment and derange the command system of the opposing force. In such a case, the tanks are given a rendezvous point where they assemble and return to the main body in time for use with the principal attack.
(3) The peculiar local conditions of the war in North and Central China caused certain additional uses to be made of accompanying tanks. In the case of the attack of a walled town, the tanks moved out ahead of the infantry and cleaned up the outer defenses of the town gates. Then, while the infantry closed in to assaulting range, the tanks stood by close to the wall and neutralized the defenders of the rampart by the fire of their machine guns. After the infantry entered the town, the tanks again led the way and assisted in mopping up hostile elements that continued to resist. Such use of tanks is possible only against an enemy weak in antitank weapons.
(4) Leading tanks. It is doubtful whether the Japanese have had actual experience in the use of leading tanks, although the new Combat Regulations contemplate their use in cases where tanks are available in plentiful numbers. The Japanese first satisfy the requirements for accompanying tanks; those in excess of this requirement are organized into a leading tank detachment under division control. Several minutes ahead of the main attack, they rush deep into the zone of the hostile artillery and command system. They are given a zone of action, a rallying point, and a mission type of order that includes the subsequent course of action. Artillery support is planned carefully to cover the tanks through the forward area of hostile antitank weapons. Long range artillery coordinates its fire with the movement of the tanks so as not to interfere with their progress.
(5) Miscellaneous uses of tanks. The following miscellaneous use of tanks have been noted:
(a) Tanks were used to break through the defenses at the mouth of a defile, reconnoiter the inner defenses, and return.
(b) Tanks executed local battlefield liaison and reconnaissance missions as well as transported essential supplies in the areas beaten by small arms fire.
(c) Tanks were used as the main force in a frontal holding attack, while the remainder of the division enveloped a flank.
(d) Tanks were used to block the escape of retreating forces through the rear gates of walled towns.
(e) In November, 1937, three Japanese tanks formed a stationary battery while infantry were crossing the Suchow Canal. In February, 1938, 40 tanks were similarly employed at the crossing of the River Hwai. A few months later, tanks were used as pursuit troops driving along both sides of the Yangtze at the same time. In 1938, during the attack on Suchowfu, tanks made a wide circling move and cut the railway lines nearly 40 miles from the city.
(f) Against road blocks the Japanese used their tanks to pin down the troops covering the block, while the infantry tried to infiltrate and attack from the rear and flanks. In Malaya, whenever the infantry was held up, the Japanese brought up tanks to support the attack, overcoming any obstacles caused by demolitions, or ferrying tanks over fast-flowing rivers. Normally, they attempted to force the tanks through frontally, and, when successful, broke in among the troops on both sides of the road. When the tanks were held up frontally, they were brought in on the flanks. At the battle of Slim, Malaya (1942), the Japanese attacked with 30 tanks. These moved parallel to the main highway for several miles through roads of the adjacent rubber plantations and then cut in to the main road, moving straight down it to a depth of 20 miles.
(g) At Milne Bay a few light tanks were used as were about 12 on Guadalcanal. On each occasion their use was restricted by the terrain, but on neither was there any outstanding tactical employment.
b. Defensive. On the defense, the division commander usually holds his tanks initially in division reserve, under cover from artillery fire and attack from the air. Eventually they are attached to the infantry making the division counterattack. They are considered particularly valuable in stopping a hostile mechanized force, for the defensive tanks can defeat a superior number of the enemy's if the latter have run away from their artillery support or have become dispersed. Occasionally, the defending commander may use his tanks in a raid on the hostile assembly areas before the enemy attacks. In all cases, tank actions must be supported by carefully arranged artillery fire to neutralize the hostile antitank guns.
4. MECHANIZED UNITS. a. Organization. In China the Japanese have used provisional mechanized units, varying in size and composition according to the material at hand and the mission to be accomplished. In general, these units have a strong nucleus of tanks, supported by motorized infantry, engineers, field and antiaircraft artillery, anti-gas, and signal detachments. The whole force is supplied by a truck train formed from line of communication
(heitan) supply units. Observation aviation is usually attached.
b. Tactics. (1) Offensive. (a) A mechanized force normally receives an offensive mission whereby advantage can be taken of its high mobility and capacity for independent action. In general, its tactics are about the same as those of a large cavalry force. By secrecy and rapid movement (usually at night) it surprises the enemy force in a terrain suitable for the tanks which form the backbone of the combat strength of the command. The commander, keeping his tanks under central control, masses them for a quick blow in a vital attack direction. The motorized infantry receives any or all of the following missions: (1) It covers the tanks and facilitates their action. (2) It holds the ground won by the tanks. (3) It occasionally takes over a front in a holding attack or makes an attack to create a diversion either by day or night. The infantry always fights dismounted but stays in its carriers as long as possible. The artillery performs normal support missions with special attention to enemy antitank guns.
(b) As a mechanized force draws near the enemy, the commander prepares tentative plans to meet varying hypotheses as the situation is susceptible to sudden changes in this fast-moving type of combat. He activates reconnaissance and security agencies, meanwhile gradually reducing the depth of his dispositions. As the enemy situation clears somewhat, he chooses an assembly area in conformance with his tentative scheme of maneuver. This area is as close to the enemy as is consonant with safety. If there is danger of a sudden collision with the enemy, the commander may traverse the final distance between himself and the enemy by bounds from one terrain line to another.
(c) A bold envelopment or turning movement is the maneuver best suited to a mechanized force. Such a force often will march at night, assembled in darkness, and attack at dawn. In the assembly area, reconnaissance is made, order is restored, and missions are assigned for the subsequent attack. When the enemy situation is vague, the usual objective is a terrain feature the possession of which is essential to the enemy. In the final deployment troops remain in vehicles until the danger of hostile fire forces them to dismount. When this has occurred, empty vehicles are parked under cover from air and ground observation. The unit reserve is usually infantry but on occasion may include some tanks. The detailed conduct of the attack follows the tactics of a large cavalry force.
(d) Mechanized units are particularly well adapted to pursuit and exploitation. The objectives assigned to them are those suitable to any pursuit force, but their range of action permits a deeper penetration into the hostile areas. It is in this form of action that the Japanese mechanized forces have found their chief employment in China. Examples abound in which such units have cut the roads and railroads behind a Chinese front on the verge of collapse and have assailed the hostile rear. The broad plateaus of Suiyuan and Chahar have afforded a terrain particularly favorable to such armored tactics.
(2) Defensive. Since the defensive nullifies the mobility of a mechanized force, it is a form of combat to be avoided. However, it may be imposed by the situation. In such a case, the commander usually disposes his dismounted infantry in a discontinuous line of strong points, with most or all of the tanks held in reserve. The defense is conducted along customary lines, with the principal concern of the commanders being the engagement of his tanks in a counterattack. In the usual defensive situation the enemy will be superior in tanks; hence, the commander must endeavor to stage the decisive tank action out of range of the hostile artillery but within the range of his own antitank guns. Under such conditions, his inferiority in tanks is compensated for by the supporting fires of his artillery. When the hostile tanks are defeated the crisis is passed and the counter-offensive often is justified.
5. COMMENTS. The value of mechanization is fully appreciated by the Japanese Army, and its armored tactics should not be taken lightly. It has acquired considerable battlefield experience in small scale tank actions and in the use of improvised mechanized forces. Such units as have been encountered do not have the striking power of the elaborated mechanized forces of Western powers.
1. GENERAL CLASSIFICATION OF JAPANESE ANTIAIRCRAFT MEASURES. a. Passive. Passive antiaircraft measures consist of concealment, camouflage, and dummy works. By these means, an attempt is made to hide the defended object from air observation, to make it look like either a natural part of the terrain or a non-military objective, or to construct dummy works so that they will draw the fire of attacking aircraft. Frequently combinations of these methods are used. On the whole, camouflage in the field and of small installations has been excellent, while attempts at camouflage of large installations so far covered have not been particularly successful. Manuals place considerable emphasis on the use of both large and small-scale smoke screens, but this has not so far been observed in practice.
APPLICATION OF TACTICS
Section VI. ANTIAIRCRAFT
b. Active. Active measures in general are as follows: (1) Antiaircraft guns of calibers ranging from 7.7-mm to 127-mm are known to be in use. These are high velocity weapons with effective ranges up to altitudes of 25,000 feet. They are used for direct action against attacking planes, to shoot them down and to break up their bomb runs. Ammunition ranges from incendiary to high explosive fragmentation projectiles with time fuses.
(2) Barrage balloons are used for protection against dive bombers. These are usually camouflaged a greenish blue when defending objects on the water, and are difficult to see. They offer no protection against high level bombing, because their maximum elevation is not great enough--usually being about 1,000 feet.
(3) Night fighter planes, equipped with radar or operating in conjunction with ground searchlights, are used to seek out and destroy hostile planes.
2. ORGANIZATION. a. Areas to be defended. Areas to be defended are: (1) important points, such as bridges, beachheads or docks, anchorages, isolated military stores, and movement of troop columns thru defiles; (2) important towns or cities; (3) airfields. No definite priority can be placed on these areas, for it depends on their relative importance which is subject to change.
b. Home defense. For active defense, the Japanese homeland is divided into antiaircraft defense areas. The organization of defense measures is usually entrusted to the senior Army officer in the district who coordinates the efforts of military, naval, and civilian units. The Army units include the fortress artillery of fortified zones, individual units of field antiaircraft artillery, and army aircraft.
3. SEARCHLIGHTS, FIRE CONTROL INSTRUMENTS, AND WARNING METHODS. a. Searchlight tactics. (1) At the end of 1943, Japanese searchlight operation was still ragged and inefficient compared with Allied standards. However, they were rapidly improving their methods. There were indications that some type of radio direction finder for searchlights was coming into use by the Japanese in certain areas. Reports state that some Allied aircraft have been picked up as soon as the searchlights were turned on and illuminated for as long as three minutes, even when evasive action was taken.
(2) It is believed, however, that the majority of Japanese searchlights are directed by sound locators.
(3) Lights apparently are controlled centrally, as they are frequently illuminated simultaneously, searching in the same direction.
(4) Cooperation between searchlights and night fighters has improved. Searchlights have frequently been seen waving vertically or scissoring, especially when about to focus on a plane. Searchlights have been waved together vertically on one side or the other of hostile aircraft, presumably to give direction to a night fighter.
(5) Emplacements are generally circular and from 15 feet to 35 feet in diameter, with most being of the larger size. Searchlights are generally em-placed in an oval pattern with the defended area in the center.
b. Fire-control instruments. (1) Japanese fire control instruments examined to date show no new improvement, and in general, they are obsolete judged by modern standards. The standard heavy antiaircraft (75 mm.) guns recovered in the Aleutians, the Solomons, and New Guinea were all manually operated from data transmitted by voice to the gun crew members from the operators of off-carriage instruments. No directors have been used in conjunction with the 40 mm, 25 mm, or 20 mm automatic cannons. However, reports indicate that Allied flyers have experienced heavy accurate antiaircraft fire over Japanese bases, even through cloud cover, which would seem to indicate that fire-control equipment of more advanced design is in use.
(2) It is a common practice for single Japanese planes to fly at the same altitude as enemy bombers although well out of range. These planes make no effort at interception; their evident purpose is to transmit to the guns data as to the elevation and speed of the target, for when these "spotter" planes are present, the corrections of antiaircraft fire have been rapid.
c. Warning methods. Three warning methods are in general use by the Japanese:
(1) Sound locators of the trumpet type are still used, although they are not very effective against modern high speed planes.
(2) Radar is in use in many important defenses, but its range appears to be rather limited. Development by the Japanese in this field has lagged behind that of Allied nations. The number of occasions when Allied planes have reached their objective undetected would indicate that the use of radar is limited.
(3) Visual observers are extensively used to give warning. Outposts with the mission of reporting the movement of hostile planes are placed in advantageous positions. These outposts attempt to get as close as possible to points from which they can observe the movement of enemy planes from airfields. It must be expected that some of these groups will actually be within the enemy lines. Other observers are posted on high terrain features and on ships. They work in short tours of observation with frequent relief, and report plane movements by radio. Their equipment for observation is usually limited to binoculars. There are instances where the only
warning system employed consisted of the gun crew itself, acting as observers.
4. POSITIONS. a. Location. (1) Japanese antiaircraft companies observed are usually situated within a 1-mile radius around the area to be defended, with the greatest concentration of guns between the defended areas and the sea approaches thereto, along shore lines, and in the direction of enemy territory. Guns are mounted both in single positions and in batteries of from 2 to 12 guns. The distance between guns in both heavy and medium companies varies from 40 to 250 feet, with the majority of revetments between 50 and 110 feet apart. Machine guns usually are placed either within the group or a short distance from the group for protection against low flying aircraft.
(2) The only distinction between the locations of medium and heavy antiaircraft companies is that medium companies are rarely placed outside the 1-mile radius except along beaches, while some heavy companies may be as far as 4 miles from the defended area.
b. Arrangement. In general the arrangement of the positions is dependent on the number of guns involved and the terrain. When 3 guns are used, the position is usually in the form of a triangle, with 1 gun at each corner and the command post in the center. In the case of 4 guns, the shape of the position is usually rectangular. If more than 4 guns are employed, the position is normally in the shape of a shallow arc. Small caliber, automatic guns are normally employed nearby for close in protection from low flying planes. Where the terrain permits, some gun positions may be located on commanding ground, thus providing for all around traverse. Command posts vary in both number and location relative to the gun positions. They are usually located inside and near the mid-point of the battery pattern.
Figure 89. Four Gun Heavy Antiaircraft Battery (Emplacements Empty). Emplacements are built of earth over which grass has grown. Pattern is a shallow arc with fire control installations in center. A three-gun light antiaircraft and a two-gun light antiaircraft are also present. The large emplacements could house 75-mm or 105-mm guns. The small emplacements are probably for heavy machine gun or 13-mm antiaircraft.
Figure 89. Continued.
Figures 90, 91. Note the Rough Trapezoidal Pattern of this Four-Gun Heavy 75-mm Antiaircraft Battery. The command post is centrally located. This pattern is used most often at permanent, strongly established Japanese bases. The emplacements are shallow excavations with thick, strong revetments.
5. GUN EMPLACEMENTS. a. Standard type. The standard type of gun emplacement used almost exclusively is of circular or semi-circular construction, either level with the surface of the ground or slightly dug in. It is surrounded by a revetment built up of logs, coral, sand bags, and other materials to protect the gun and its crew. The opening usually is protected by a blast wall. A variation of this type of emplacement is constructed with two concentric circular revetments. (This type is commonly called the "doughnut.") The almost rigid adherence to these types of emplacements makes them readily identified from the air. Recently more care has been taken to conceal them by decreasing the slope of the revetment and planting it with natural growth so that shadows will not be so apparent.
b. Sizes. The caliber of the gun can be determined roughly from the size of the emplacement. Approximate sizes of emplacements for certain guns are listed below:
105-mm Normally 25 feet in diameter. 75-mm mobile Normally 20 feet in diameter. 75-mm static Normally 15 feet in diameter. Machine cannon Normally 13-15 feet in diameter. 13-mm machine guns Normally 8 feet in diameter.
c. Camouflage. Little or no effort is made to camouflage or conceal the guns, but extensive use is made of dummy and alternate positions, even to the extent of constructing dummy guns.
6. EMPLOYMENT OF ANTIAIRCRAFT. a. General. It is normal to attach antiaircraft units to divisions. Their missions are the same as those assigned in Allied armies, but the division commander is given direct control over them.
b. All antiaircraft guns are dual purpose, most being capable of a minus depression; however, there is no evidence of armor-piercing ammunition for the larger caliber guns.
Figure 93. Sketch of 75-mm antiaircraft gun in earth revetment.
Note partially excavated type of emplacement with high revetment and built-in Ready Magazine.
Note also zigzag entrance trench.
c. Methods of fire. (1) All guns in a position frequently concentrate their fire on the leading plane of a formation and fire on succeeding planes if time permits.
(2) Colored spotting rounds often are used.
(3) Instances of accurate fire above the overcast indicate the probability of radio direction equipment.
(4) In areas where the ground is often blanketed with clouds, such as in the Aleutians, all guns direct their fire at the opening in the clouds where the enemy planes may normally be expected to appear.
(5) Barrage fire has been employed.
(6) In jungle country, the Japanese have shown an increased tendency to attack with light machine gun and rifle-fire against low flying aircraft. Such fire is encountered particularly along lines of communication, and its effectiveness should not be discounted.
Section VII. ANTITANK DEFENSE
1. GENERAL. a. Background. (1) The antitank methods adopted by the Japanese Army in antitank measures follow normal modern practice, except that the army as a whole is weak in antitank weapons. More thought, however, is given to the simpler forms of antitank defense, such as the use of antitank mines, incendiary grenades, gas grenades, obstacles, and the employment of special infantry assault squads (tank fighters).
(2) Experience in fighting Russian tanks at Nomonhan, Manchuria, in 1939 gave the Japanese Army an initial warning that more definite provisions must be made in its tactical organization for handling enemy tanks. As a result of much consideration of this problem, which was stimulated by the successful use of tanks by the Germany Army in the early days of the present war, a definite plan for resisting tank attacks was adopted. There is every indication that the Japanese have been studying and applying modern principles of antitank defense with the same careful attention which they devote to other tactical problems.
b. Exploitation of tank disadvantages. The Japanese envisage the inherent disadvantages of tank operations to be as given below, and their antitank instruction stresses taking every advantage of these conditions.
(1) Natural and artificial obstacles.
(2) Long tank columns which are difficult to camouflage.
(3) Adverse weather conditions which may prevail.
(4) Unfavorable working conditions and difficult observation which lower efficiency of crews.
c. Tank-hunting. Since the Japanese Army teachings lay a pronounced emphasis on coming into close contact with enemy tanks, it is well to draw attention to the fact that tank-hunting tactics are likely to be employed to a greater extent by the Japanese than by other armies. The reason for this is
Figure 94. Six-Gun Heavy (105-mm) Antiaircraft Battery.
Note shallow arc pattern with command post in center.
Figure 94. Continued.
three-fold: (1) it is another manifestation of the Japanese spirit of the bayonet--the hand-to-hand encounter, in which the individual is expected to triumph over material, even if armed only with grenades; (2) the Japanese appear to be short of modern anti-tank guns, and only by denying one front do they produce reasonably strong concentrations on another; and (3) most of the ground over which they have been fighting lends itself to a close assault.
2. ANTITANK WEAPONS AND ANTI-TANK UNITS. a. Weapons. The Japanese Army generally has disliked single-purpose weapons. However, this dislike was abandoned from necessity, and early steps were taken to produce a 20-mm automatic antitank rifle which has been found with units in the field. It is carried by 4 men in combat, and transported on a cart or packed on 1 horse if not carried by hand. While the 37-mm gun is still retained in service and is used as a dual-purpose weapon, the 20-mm automatic antitank rifle is believed to be primarily used for antitank purposes. Other field and antiaircraft artillery weapons are considered suitable for use against tanks. A modern 47-mm gun, equipped with a high speed mount, has recently made its appearance. This weapon should have an effective antitank performance, while its low silhouette will aid in its concealment.
b. Nondivisional units. Nondivisional antitank units did not exist in the Japanese Army before the Nomonhan incident, but as a result of experiences in fighting Russian tanks, these independent antitank units were formed for attachment to divisions when necessary.
3. PASSIVE DEFENSE MEASURES. Concealment, camouflage, obstacles, reconnaissance, and warning nets are considered essential.
4. ACTIVE MEASURES. These include-- a. Action by antitank guns, accompanying guns, and mortars.
Figure 95. New Type Double Revetment (Nusa Island battery across Wavieng channel),
showing detail of construction.
b. Bullet splash from machine guns and rifles at a short range (at least one squad firing at each tank).
d. Tank fighters. These comprise men with special training and equipment for direct assault on tanks.
5. ANTITANK TACTICS. a. Mines. A cheap method of passive defense against tanks is by the use of tank mines. In an exercise involving an infantry division, 12,000 mines were laid by all units of the division. Where enemy units are known to have tanks, the laying of tank mines is considered the most essential duty of the division engineer regiment. The mines are placed in a conventional manner
covering the logical routes of tank approach. Bridges in defensive areas are habitually mined, and any bridge which has been in Japanese hands must be carefully examined for the presence of contact mines before a tank unit is allowed to cross. Tank barricades have all possible detours heavily mined, and it is common practice to lay a few mines under temporary barricades with the idea that if the enemy removes the barricade, he will not suspect that mines have been laid in the ground underneath.
b. Tactics. A Japanese military term applying to antitank defense is "dansei bogyo," which is translated as "an elastic defense" and is highly descriptive of their entire theory of antitank defense. Briefly, this method of combat does not provide for strong resistance to tank attacks along front lines. Not more than 20% of available heavy infantry weapons are employed against a tank attack from front-line positions. On the approach of a tank attack all units, with the exception of one squad per platoon, fall back to positions from 800 to 1500 yards in the rear. The squad from each front-line platoon left in position scatters widely and, under cover of smoke laid down by the use of the grenade discharger, attacks the tanks with incendiary grenades as they come through the smoke. It is contemplated that this initial stage of the fight will scatter the enemy tanks, reduce control, and cause some casualties. If the tanks overcome the resistance of the front-line detachments they come under fire from the main strength of all available weapons of the infantry. While this and the front-line combat have been going on, some of the division artillery moves forward to positions from which it can fire with direct laying. If the heavy weapons of the infantry are unable to stop the attack, the main infantry strength, using smoke and incendiary grenades, makes a direct attack, relying on the artillery to their immediate rear to handle any tanks that get through. The main feature of this defense, as stated by provisional regulations, is that once an attack is stopped the enemy is pinched off, and by the operation of scattered units can be destroyed with grenades or any available weapons; and the infantry, although scattered, still can offer successful opposition to enemy infantry attempting to exploit the advance of the tank units.
c. Estimate. While it may appear that the Japanese Army will offer but weak resistance against a tank attack because of the nonavailability of modern weapons in sufficient numbers, this assumption should not lead to the belief that strong and suicidal resistance by individuals will not be offered.
6. DETAILED METHODS OF ATTACKING A TANK. a. Choice of ground. When employing tank-fighters, it is desirable to choose ground where tanks must travel slowly and where the attack does not interfere with the action of anti-tank guns.
b. Special troops. Each rifle company (sometimes machine-gun and heavy-weapon companies organize similar detachments) trains certain individuals as tank-fighters, and these are specially equipped for such action. Each man is armed with anti-tank mines and smoke hand grenades.
c. Methods. Three ways of attacking tanks are: (1) The tank-fighter crawls toward the tank under cover, until he is within the dead space of the tank weapons. Next, he throws the mine, attached to a long string, about 15 feet in front of the tank and, by means of the string, pulls it directly under the tank.
(2) Several pairs of tank fighters move forward under cover and place a number of mines in front of the tank in such a manner that the tank must drive over one of them.
(3) A number of mines are fastened, 1 foot apart, to a 150-foot line. Two men conceal themselves with this chain of mines and draw the mines across the path of the tank as it approaches.
The tank-fighter is also taught to attack the tank by jumping on top, usually from the rear, and damaging the guns or rotating mechanism of the turret with picks. The pistol may be used to fire on the crew through openings in the tank. Another method is to blind the tank crew by throwing a shelter-half over the turret, covering the slits with mud, or "smoking it out." Naturally, all these forms of assault are feasible only if the friendly infantry can neutralize the hostile infantry accompanying the tanks. Tanks have been delayed, and finally stopped, by driving 3-inch wooden poles or 1- to 1 1/2-inch rods between the spokes of its wheels. Magnetized armor-piercing mines are also used at times.
7. EMPLOYMENT OF ANTITANK WEAPONS. a. Allotment. In country that is suitable for the operation of tanks a company of Japanese infantry may be found to be supported by from 2 to 6 antitank guns (37-mm or 47-mm). The infantry regimental antitank guns either may be allotted to forward battalions or, on rare occasions, held in reserve under regimental control. The 20-mm antitank, automatic rifle is described by the Japanese Infantry as "delivering antitank fire at short range and engaging the enemy's foremost heavy weapons." If there is any danger of a night attack by tanks, the 20-mm weapon may be posted forward of the main line of resistance and supported by tank hunting detachments.
b. Siting. The bulk of the antitank guns allotted to a position are sited as far forward as possible. Great stress is laid on siting guns in concealed positions and camouflaging them. To quote from Japanese regulations, "positions are to be selected at well covered points near the front line." Experience has shown that once dug in, these weapons are difficult to locate. It is likely that an antitank gun will sometimes be sited in very thick cover, with a small fire-tunnel cut out to enable it to cover a trail or other likely area for tank approach. The Japanese have sited machine guns in this way, and
the practice well may be applied to antitank guns. Guns also may be sited on steep ridges or rocky slopes, from which positions they can fire at hostile tanks while themselves remaining inaccessible. Alternative positions are prepared, the regulations stressing that "it is advisable to move the gun from place to place thus avoiding casualties from enemy fire." In action the fire unit is generally the individual gun (a section), and the gun commander chooses suitable targets and directs fire upon them. While most of the guns are sited in foremost defended localities, a few are held in the depth of the position with the apparent task of dealing with penetration of enemy tanks. In the event of such penetration, infantry regimental guns, as well as field artillery weapons, also will engage the hostile armored vehicles. The fire plan of the infantry weapons is coordinated with that of the antitank unit. Except for reserves--if any--all guns are sited to cover the most likely lines of approach of enemy tanks. They are also sited to cover obstacles. An infantry platoon often is disposed on the route of approach in advance of the main position, but within range of artillery support from it. This platoon may have an antitank gun attached to it.
8. EXAMPLES OF POSITIONS. a. Natural and artificial obstacles combined. The position illustrated in figure 96 was prepared by the Japanese near Akyab, Burma. It provides an interesting example of an all-round tank obstacle, partly natural and partly constructed. A ditch, approximately 14 feet wide and 7 feet deep was dug as shown. Dirt, thrown out on both sides formed a small parapet, while water filled the ditch. The trench system dug near the ditch included 7 covered positions, each measuring 45 by 30 feet.
b. A plan for antitank defense. In figure 97 there is shown a Japanese plan for antitank defense of an area in Burma. The following troops and guns were allotted to the position:
(1) Area No. 1 was to be garrisoned by 1 company of infantry, reinforced with half a company of heavy machine guns (4 guns), 2 antitank guns, and 4 infantry (mtn) guns (75-mm).
Figure 96. Antitank defense position.
(2) Area No. 2 was allotted 1 infantry company with half a company of heavy machine guns (4 guns), 5 antitank guns and 4 infantry (mtn) guns (75-mm).
(3) Area No. 3 was assigned 1 company of infantry, and 2 Mountain (inf) guns (75-mm).
(4) Area No. 4 was defended by 1 company of infantry, one half of a heavy machine gun company (4 guns), 4 antitank guns and 2 Mountain (inf) guns (75-mm).
(5) Area No. 5 was allocated 1 platoon of infantry and 1 heavy machine gun platoon (2 guns).
(6) Area No. 6 was assigned 1 platoon of infantry and 4 antitank guns.
c. Obstacles. At Butaritari Island, Makin Atoll, the Japanese dug deep antitank ditches outside of
Figure 97. Japanese Plan for Antitank Defense.
Figures 98, 99. Antitank obstacles.
their main defenses at the tank traps, with winding narrow roads leading into the outer edges. (Fig. 98.) The crossings were covered from antitank gun pits and machine gun nests. Palm logs served as a tank barricade near one tank trap. (Fig. 99.)
Section VIII. JUNGLE WARFARE
1. TERRAIN. Jungle warfare, as referred to in this manual, is warfare in the larger island and mainland areas which to a great extent are covered with dense tropical jungle. These jungles are interspersed with open, grass (kunai) covered areas, and frequently, along the coast, large coconut plantations are under cultivation. Swamps are numerous in the lower areas, and streams rise rapidly after the heavy tropical rains. The terrain differs widely, but in general it is rugged, except along the coastal strips. The principal means of communication are over native trails (tracks) ; there are very few roads that will stand up under the load of military traffic. Visibility in the jungle is limited to a few yards.
2. EARLY JAPANESE SUCCESSES. The tactical principles and illustrations in this section are based on operations in the Solomons, New Guinea, Malaya, and Burma. The Japanese enjoyed remarkable success during the Malaya and Burma operations and during the early phase of the New Guinea campaign. They had trained extensively for this type of warfare; their known lack of modern motor transport did not hinder them, and their reliance on commandeered local supplies and equipment materially helped to solve their supply problems in Malaya and Burma. In later operations, the Allied forces have adapted themselves to jungle combat from the standpoint of organization, training, and equipment, and have shattered the myth of the invincibility of the Japanese in this type of warfare.
The principle that the advantage lies with the side which holds the initiative applies in jungle warfare as well as in other types.
1. GENERAL CONSIDERATIONS OF OFFENSIVE COMBAT. a. Reconnaissance. Reconnaissance is recognized as essential, and great stress is placed on it. Preliminary map reconnaissance and study of aerial photographs are normal, and the employment of advance agents and fifth columnists is standard practice. Reconnaissance patrols are used extensively; they are well trained in sketching, and their composition and equipment are planned in considerable detail. A variety of ruses is employed in accomplishing their reconnaissance mission. They frequently engage in small-scale combat and purposely expose themselves to determine the location of hostile automatic weapons.
b. Security. Security in the advance is accomplished through the normal use of advance guards, rearguards, and flank patrols. In the jungle, the activities of flank patrols are of course limited. The Japanese are not especially security-minded, particularly in bivouac areas, and leave their lines of communication and headquarters installations relatively unprotected. Their theory is that by pressing a vigorous offensive the enemy will be kept on the defensive and have little opportunity to do much damage on the flanks and rear.
c. Surprise. Surprise is a cardinal principle of all Japanese action. It is accomplished through rapidity of advance, deception of all kinds, and infiltration and demonstrations in the enemy rear; in short, all means available are utilized, and speed is greatly emphasized.
d. Fire and movement. The standard principles of fire and movement are observed. The fire generally is placed in the area of the holding attack, while the main effort maneuvers silently. Preparatory fires seldom are used; the common method of attack is to attempt to approach within assaulting distance of the objective unseen by the enemy.
e. Mutual support. Mutual support by and contact between adjacent units are poor by accepted standards. Advance guards of parallel columns are not coordinated and generally do not maintain contact with each other. Frequently, in attack orders, each unit is given an objective and a direction, but the details of lateral communication and coordination are not covered. This is especially true in the case of infiltration, where units, and even individuals, work their way through hostile lines and rendezvous at some predetermined point.
f. Tenacity. The Japanese will hold tenaciously to the advantages gained through offensive action. They teach that the assault must immediately be followed up by pursuit, but in the later phases of their offensive campaigns this doctrine has not always been carried out. If their attack is retarded, they will hold what they have gained and will use other units, which they have kept in reserve, to maneuver and put pressure on the flank or rear of the enemy.
g. Pattern of offensive. Japanese offensive action seems to follow a definite pattern, and in many instances is drill-like in its execution. Orders are brief and to the point. Supply and administrative details are almost ignored. Simplicity is gained at the expense of general coordination, emphasizing the Japanese belief that the infantry can gain its objective solely by vigorous offensive action.
h. Faults. There is a notable tendency toward disorganization when a commander becomes a casualty, although recently emphasis has been placed on correcting this deficiency. Unity of command tends to break down in larger attacks because of lack of coordination between units.
i. Reserves. Japanese units of all sizes habitually hold reserves. These vary in strength, depending on the situation and the mission, but in general they approximate one third of the infantry strength.
j. Maintenance of direction. Maintenance of direction in the jungle is extremely difficult. Roads are practically non-existent, and trails seldom run in the right direction. Also, since visibility is limited, it is impossible to march on terrain features. Reliance therefore is placed on the compass, and advance and guide parties habitually are equipped with this instrument. Routes are selected by these parties, and marking is accomplished by blazing trees or stringing long vines. For night marches, luminous wood is used.
2. FORMS OF ATTACK. a. Tactical forms of attack. The main attack is normally an envelopment of one or both flanks, or a penetration. Frontal attacks are not recommended and, when they are made, the aim is generally a point penetration, which may be followed by an envelopment on one or both sides of the breach. The secondary attack is normal and usually frontal. Generally it takes the form of a demonstration, accompanied by obvious movements and noise, and is used to cover the movements of the main effort.
b. Envelopment. Envelopment is the most usual form of Japanese attack. It has been said by the Japanese that the perfect solution to a tactical problem is a neatly performed stratagem, followed by an encirclement or a flanking attack pushed home with the bayonet. The envelopment may be of one or both flanks, and although the wide envelopment is taught, in general practice the close-in envelopment is customary.
c. Point penetration. The point penetration frequently is employed. It invariably is directed against a soft spot that has been discovered by patrol activity and reconnaissance, or created by night action against heavy weapons that have disclosed their location by premature firing as a result of Japanese deceptive measures. Since their tactical doctrine states that once an advantage has been gained, it must be exploited to the fullest, it can be
expected that the main strength of the Japanese attack will be directed against this point.
3. DEVELOPMENT OF OFFENSIVE COMBAT. The advance and approach march differ from that in open warfare because of the close nature of the terrain, where troops more often are restricted to one route of advance. In dense jungle it is not feasible to break down into small columns and extend in width because separate tracks would have to be cut for each column--a slow and tiring process. The usual formation is an advance in one column, with elements in the rear echelon available for maneuver to either flank. Rapidity in the advance is essential and is limited only by the rate of march of the heavy weapons elements.
4. CONDUCT OF THE ATTACK. a. Meeting engagements. There have been few clear-cut examples of meeting engagements except in the early stages of the war, and then in fairly open jungle. The advance guard, upon contacting the enemy, promptly notifies the elements in rear and attempts to knock out the opposition. If this does not seem readily possible, the advance guard, by use of ruses, attempts to make it appear as though it is deploying for battle. At that point it seeks out the flanks of the enemy and attempts to locate his heavy weapons. In the meantime, the main body moves to one or both flanks and advances as rapidly as possible with the intention of striking deep in flank or rear. If the hostile force presses the attack against the advance guard, it disperses to the flank and joins the main body.
b. Against deployed defense. Two methods of attack commonly are used against a deployed defense. First, an attempt is made by maneuver to strike the enemy in flank or rear; the actions are similar to those described for meeting engagements. That is, a demonstration is made on the front, using much noise, movement, and promiscuous firing to simulate strength, while the main force moves silently to a flank to make the envelopment. The second method is to feel out the front for soft spots. By use of ruses and deceptive tactics an attempt is made to locate automatic-weapons positions. When these are located, a heavy concentration of mortar fire is brought down so that troops may reach assaulting distance without being discovered. The assault is made, usually on a narrow front, and if the objective is not attained at once, succeeding waves follow through in an effort to overwhelm the enemy. The objective generally is set deep in enemy territory, and the assault attempts to carry straight through to it, leaving for succeeding elements the job of mopping up and, if necessary, consolidating. Intermediate objectives seldom are designated in *the case of daylight attack.
c. Against position (static) defense. Tactical principles employed in an attack against a position defense in the jungle do not materially differ from those already discussed in open warfare.
The difficulties of supply, communication, and control are great, and as a result there have been few successful coordinated attacks. Attempts frequently are made to attack a position at several points simultaneously, but most of these have resulted in piecemeal attacks. The Japanese belief in the inherent superiority of their infantry often leads them to attack without adequate artillery support, although their tactical doctrine calls for the neutralization of hostile artillery fire before attacking a position. This has seldom been accomplished, and, against the fire power of modern weapons, such an attack is usually disastrous. As in other types of attack, extensive use is made of demonstrations and other ruses to mislead the enemy into committing his reserves, as well as to discover the location of automatic-weapons and security detachments. If the position is entered, the leading elements will continue on through, not waiting to consolidate their gains until they have reached their objective or until they have been definitely stopped. Attacks on important positions often are rehearsed beforehand.
5. PLANS OF ATTACK. The plan of attack is thought out carefully by the commander and his staff, but many details, normally considered necessary by other armies, are omitted when the actual order is issued. The disposition of troops is not covered in detail, and boundaries are seldom given, for commanders depend on the training of their subordinates for the detailed conduct of the attack. By accepted standards, the directions issued to the artillery and other supporting arms are generally vague. Supply and administrative details as well as signal communication instructions are covered superficially. Emphasis is placed on the utilization of captured supplies and weapons, and a study of enemy weapons is included in Japanese training. Rapidity of the advance and vigorous attack are counted upon to overwhelm the enemy, and reliance is placed on the ability of the Japanese soldier to live off the land, fight with the bayonet, and withstand hardship until the objective is taken. It is evident that the Japanese Army is expected to be so well trained that detailed orders are unnecessary.
6. SUPPORTING FIRES OF INFANTRY WEAPONS. a. Machine guns. Machine guns normally are employed in pairs and are placed well forward to support front-line infantry. They go into position under cover, and advance preparations are made so that, by opening fire accurately and with surprise effect, fire superiority over the enemy may be quickly gained. Positions are selected with a view to advancing as the attack progresses. Forward movement to new positions may be by individual gun, or by pairs, depending on the terrain and the situation, but preference is shown for the latter. It is normal for the guns of the platoon to fire on the same target. Emphasis is placed on close cooperation with front-line infantry, but the
guns are not used as a base of fire to the extent practiced by the U.S. Army.
b. Antitank guns. Antitank guns have a primary antitank mission, but in the absence of tank targets they fire on infantry. They are placed in position well to the front and go forward with the advance of front-line infantry.
c. Battalion and regimental guns. Battalion and regimental guns are assigned the primary mission of neutralizing the enemy's heavy guns and machine guns. They are located well forward and are prepared to move ahead to new positions with the infantry. They, too, are put in position under cover and seek surprise in opening fire. They are prepared to carry out indirect fire in missions, and, as in the case of antitank guns and machine guns, are directed to give close support to the front-line infantry.
d. Long-range fire. Although long-range fire of heavy infantry weapons is discussed in training manuals, it is seldom practiced. The bulk of the supporting weapons are placed well forward, and depend for the accomplishment of their mission on a heavy volume of fire accurately delivered with surprise effect.
7. SPECIAL OFFENSIVE OPERATIONS. a. Raids. Raids are extensively carried out for the purpose of harassing the enemy rear, striking at command posts, destroying artillery units, and penetrating defenses. The parties making these raids are highly organized and trained. Their composition and equipment depend on the mission. (See Chap. V.) Frequently the mission is a suicidal one and these parties will go to extremes in accomplishing it.
b. Night operations. The Japanese favor the night attack. Such attack is generally made on a narrow front and has a limited, well-defined objective. Where possible the Japanese attack uphill. This prevents their being silhouetted on the skyline, and the hill itself helps them to maintain direction. Night attacks are often accompanied by excessive use of signal flares, and, usually, a demonstration is carried out at some distance from the actual point of attack. An effort is made silently to destroy known heavy weapons positions just prior to the assault. The advance to the assault often is made with great secrecy and stealth. All supporting weapons may be used in the night attack.
1. GENERAL. The Japanese dislike of the defensive is evident throughout all of their teachings. It is regarded as a negative form of combat and one to be especially avoided in view of the heavy fire power it permits a modern army to build up against them. Their system of defense therefore is based on surprise, maneuver, and counterattack.
2. SELECTION AND OCCUPATION OF POSITION. a. General. The Japanese concept of selection and occupation of positions is normal. They defend high ground generally, although in view of the advantages of concealment in the valleys, on occasion they have strongly organized these low areas for defense. There is no such thing as a normal frontage for units in the jungle; generally the terrain is so close that small units can defend the limited avenues of approach. The Japanese habitually establish an outpost line of resistance, but this frequently consists of only a few snipers and observers, well forward on the trail in front of the position. The mission of this personnel is to warn its main position of the approach of the enemy, and to slow their approach by harassing tactics. The snipers may withdraw when the pressure becomes great, but it is not unusual for them to let forward elements of the enemy pass through and then to accomplish their mission by firing on his rear and by disrupting lines of communication.
b. Artillery. (1) There has not been sufficient use of artillery in the defense to enable conclusions to be drawn as to its normal method of employment. However, certain comments made by Japanese officers may be helpful in this connection. It was recommended that they site their guns on the flanks of the infantry, thus permitting fire to be brought to within a few yards of their own front lines without endangering their own troops. This method of siting also would help to overcome the difficulty of knowing just where the front lines were.
(a) Deceptive measures were stressed for the purpose of drawing hostile fire. Two methods mentioned were the construction of dummy positions and the lighting of fires, both at a distance from the positions actually occupied.
(b) It also was recommended that artillery fire be withheld until the enemy comes within close range, since this will result in more effective fire and will not disclose the artillery positions prematurely.
(2) Considerable emphasis is placed on the infantry guns, but these have been effective only for harassing missions.
(3) Small raiding parties have been used successfully to raid and destroy artillery positions. It is believed that the Japanese may regard this as a substitute for counter-battery.
3. ORGANIZATION OF THE GROUND. a. General. Defensive organization of the ground is very thorough. It consists of a series of strong points, organized in depth and mutually supporting, each one covered from the flanks and rear by riflemen in fox holes and in trees. The position normally is organized for all-around defense. Once the position or area to be defended has been selected, the commander plans his "fire-net" or locates the positions and sectors of fire for his automatic weapons. Riflemen are disposed around these weapons, and the preparation of earthworks is commenced without delay. When the terrain permits, caves are utilized for the location of both automatic weapons and riflemen. Machine guns are recognized as the backbone of the defense and are sited both singly
and in groups. Normally, they are given only a final protective mission; their sectors of fire are extremely limited and generally close in front of the position. Lanes of fire for these guns are cut by tunneling through the underbrush, thus making it extremely difficult to locate them, but at the same time restricting their field of fire. Long range machine gun fire is not practical in the jungle. The guns are usually sited for cross fire. They may also be sited in ravines to deny this route of approach to the enemy, and on reverse slopes to catch troops as they come over the crest. Extensive use is made of alternate and dummy positions, and weapons are frequently moved from one position to another. Training publications indicate a knowledge of the use of barbed wire, but very little employment of it has been made in the jungle. This may be due to the difficulties of supply, since instances have been recorded of the use of thorny vines, interlaced to hinder the advance of the enemy.
b. Progressive improvement of position. Organization of the ground is progressive and continuous, and the longer a position is occupied, the better it will be dug in. Starting with only "fox holes," (rifle pits), the position ultimately will have a pillbox or "bunker" for the heavy weapons, constructed out of earth, palm logs and coral, or other local materials. These fortifications are improved as time permits until they are safe from practically anything except a direct hit by a large delayed-action shell or bomb. They are provided with several firing ports, and the earth is so arranged around them as to minimize dead space. Where the height of the water table will not permit these earthworks to be dug well into the ground, they are built up, sometimes to a height of six feet. Separate bombproof shelters are constructed as living quarters for personnel. Fox holes of supporting riflemen and alternate positions are connected by shallow communication trenches. No concrete or steel has been used to date in the construction of jungle pillboxes, reliance being well placed on local materials. Palm logs and coral do not splinter and will absorb a lot of punishment. Pillboxes and personnel shelters usually are constructed with a blast wall, or with the entrance at an angle to the main structure, so that grenades or shell bursts nearby will not affect the occupants. (See Defense Structures Sec. X.)
c. Concealment. Excellent fire discipline and lack of movement within the position, combined with good camouflage, are so effective that there is often doubt that the position is even occupied. Use has been made of dummy positions manned by dummy personnel in an effort to draw attackers' fire. The Japanese have made full use of the lush and rapid growth of jungle plants to conceal positions. When bunkers are used, the earth is built up with a slight gradient so as to avoid shadow and to present a natural appearance.
4. CONDUCT OF THE DEFENSE. a. Action of outposts. Individual snipers and small groups of infantry well to the front alert the main position upon the approach of hostile forces. Then they may either withdraw or remain concealed to harass the enemy during his approach. As reconnaissance or small advance parties approach the position, they are taken under fire by individual riflemen located on the flanks and in trees. Should the enemy scouts approach too closely to any of the pillboxes, they are fired upon by the covering riflemen. The automatic weapons do not fire at this early stage, and extreme care is taken not to disclose their location.
b. Action at main position. Surprise in the defense is regarded as vitally important and is achieved by withholding fire until the enemy is close on the position. A training manual states, "make preparations to be able to fire effectively, but it is important not to suffer losses by firing too quickly and exposing your position." Often fire is not opened until the enemy has approached to within ten yards of the position, and his mortar and artillery fire has lifted. If the position is attacked by a large force, the firing must begin at least when it is outside of grenade throwing distance (i.e. approximately 50 yards). Not until the enemy in force enters the lanes of fire do the automatic weapons open up, and when they do, their mission is to annihilate the enemy before he enters the position. A heavy volume of fire is delivered at close range, and this is supplemented by the use of grenade dischargers and mortars from positions located in rear of the front line. Frequently, certain gun positions that are not threatened remain silent during this initial phase, only to open fire later with surprise effect. In dense jungle, observers in trees may be used to signal the automatic gunners when to open fire, since the concealment of the pillboxes limits visibility. Even though one or more pillboxes are neutralized, remaining automatic weapons will maintain their fire to assist counterattacking troops. Garrisons are imbued with the idea that they must fight to the last man; consequently, pillboxes can be expected to hold out as long as there is an armed man left to defend them.
c. Counterattack. Counterattack is a vital part of Japanese defense. It is an offensive action, and in the mind of the soldier makes up for the "inglorious" defense he has been forced to adopt. Every unit has a counterattacking force. The counterattack is violent, and timed to strike before the enemy has had an opportunity to reorganize or consolidate. It frequently is preceded by a heavy concentration of mortar fire and is always supported by all available riflemen and automatic weapons. It differs from the normal in that it is seldom coordinated with other units, and the possibility of its failure is not considered. Since units of all sizes counterattack, the force often consists of as few as 8 or 10 men led by an officer or a noncommissioned officer. However, as the attack progresses through the position, larger counterattacks may be expected from the reserves of higher units. Because
of the difficulties of movement through the jungle, these counterattacks are usually local. As a variation of the counterattack, mortar and artillery concentrations are plotted on the positions and can be promptly laid down if the enemy occupies them or attempts to reorganize near them. These concentrations have been known to make a captured position untenable by fire alone. In the case of positions that have been well built, mortar fire may safely be brought down on the position even though Japanese troops still occupy it.
5. AMBUSHES AND ROAD BLOCKS. a. Ambushes. The jungle offers many ideal opportunities for ambush which the Japanese have exploited, and they have been trained well in this type of operation. The size, composition, and armament of the force depend on the mission. No new principles are involved.
b. Road blocks. Due to the paucity of roads, road blocks are especially effective in slowing up the movement of road-bound equipment. One method is to place a block across the road, just around a bend. The party defending the block is disposed on either side of the road, and an antitank gun, or a larger caliber weapon is located in prolongation of the road, before the bend. These weapons are emplaced close to the block and are fired at point blank range. (See fig. 100.)
The Japanese have established road blocks in rear of the enemy, along his route of withdrawal. An enveloping force or raiding party is generally charged with this mission, which is very effective in disrupting the movements of the enemy at a critical time.
6. ANTITANK DEFENSE. a. General. The employment of tanks in the jungle has been rather limited, and the standard methods of defense, such as tank ditches and mine fields covered by antitank guns, are used. Antitank mines are sometimes augmented by an additional charge of explosive. Small antitank mine fields were laid in Guadalcanal in defiles to retard the American advance, but were not very effective. Anti-mines also were employed on roads in New Guinea.
b. Methods. The close nature of jungle terrain permits close-quarter attack. Special antitank defense parties are organized within lower units and
Figure 100. Japanese road block.
trained in the technique of destroying hostile tanks. Some of their methods are as follows:
(1) When the advance of tanks is canalized, or can be anticipated, antitank mines are fastened to a long cord or vine. Two men conceal themselves on opposite sides of the route to be taken by the tank. As the tank passes between them, they quickly draw the antitank mine in front of the vehicle. Following the explosion, they attack the tank with Molotov Cocktails and small-arms fire directed at the ports.
(2) Different methods are employed to blind the tank, such as throwing paper bags of mud and lime at the ports or covering them with a blanket or shelter-half. When the tank is blinded, explosive charges are applied.
(3) Grenades or other explosive charges, fastened to a pole, are pushed into the tracks or under the treads.
(4) Magnetic mines are placed on the body of the tank where armor is most vulnerable.
7. ANTIAIRCRAFT DEFENSE. (See sec. VI.)
8. WITHDRAWAL. Withdrawal, like defense, is contrary to the Japanese concept of war. Little attention is devoted to it in their texts and training, and reference to it is made as "retreat combat." Lack of medium artillery properly to cover a withdrawal, and the difficulties of long range machine gun fire in the jungle, often result in the sacrifice of the covering force. A training manual states: "During retreat, machine guns do not think of loss, but sacrifice themselves for the army by firing fiercely against strong pressure of the enemy or against the enemy which is of greatest danger to the first-line infantry. They must make the withdrawal of friendly troops easy. Allow no enemy advantage." Mines and booby traps are used to a limited extent. In the case of night withdrawals, snipers are left behind to harass and delay the enemy.
1. EMPLOYMENT OF TANKS AND MECHANIZED UNITS. Tanks and mechanized units have been employed to such a limited extent that no new tactical principles have been observed. Successful use of medium tanks in jungle terrain by Allied forces undoubtedly will point the way toward their use by the Japanese.
2. EMPLOYMENT OF AIRCRAFT. The density of the jungle makes it difficult for air observers to see small troop movements and installations that are properly dispersed. Air observation is used, however, to locate new tracks being prepared for large troop movements. Close support of ground troops by air is difficult, because ground troops generally cannot accurately indicate their location. The Japanese have used aircraft to bomb rear areas and known installations and have supplied ground units by parachute drop.
3. COMMENTS. The Japanese have made certain comments on Allied combat methods, some of which are reproduced because they indicate their trend of thought in improving their technique:
a. The Australians and Americans are better trained and equipped than their "former enemies."
b. When making frontal attacks, it is essential to neutralize Allied fire power.
c. The enemy (Allies) have great fire power. On defense they try to annihilate us before we enter their position. Sometimes they withdraw gradually and then bring heavy concentrations of artillery and mortar fire on us. It is essential to keep close on their heels; breaking through the heavy concentration of fire in front of the enemy's position is difficult, but once through it the attack becomes unexpectedly easy.
d. Plan to split the Allied advance through the use of artillery and machine guns, and counterattack to destroy the divided groups.
e. Allied artillery is accurate. Positions constructed of coconut logs will stand up under mortar and light artillery fire, but will be destroyed by delay-fused shells and "rapid fire guns."
f. Allied troops make good use of the correct approach and do not open the attack except at extremely short range. Therefore, the Japanese should clear lanes of fire for about 50 yards in front of their position.
g. The Allied troops take limited objectives then halt to reorganize before continuing the attack.
h. The Japanese are cautioned against replying to the fire of patrols as this discloses their gun positions.
i. The Allies attempt to hold frontally and envelope; the Japanese are advised to "envelope the envelopment."
j. Infiltration is regarded as easy, because Allied outposts are not located at regular intervals and are often far apart.
k. Allied outposts can be located by searching out the wire communications leading into them.
l. Australians are excellent guerrilla fighters.
m. When two patrols meet unexpectedly, the Japanese think that a few rifle shots or bursts from a light machine gun will rout the enemy.
n. Troops are instructed to concentrate on the personnel carrying automatic weapons as these are regarded as leaders.
o. Dawn and dusk, especially during rain, are considered by the Japanese as the best times for launching attacks because the enemy have tents over their trenches and are not alert.
4. RUSES. a. Description. The employment of ruses of all kinds by the Japanese cannot be over emphasized as these play a very important part in their operations. The variety of ruses that may be used is limited only by the imagination of the Japanese commanders. A few of those encountered to date are described below:
(1) Lighted cigarettes, firecrackers, moving vehicles, and barking dogs were used opposite one of
the beaches on Singapore Island to lead the defenders to believe that the main attack would be made at that point.
(2) English speaking Japanese have called out commands in English in order to confuse their enemies.
(3) They have listened for the names of certain individuals and later called out to them by name. When the person addressed showed himself he was shot.
(4) Booby traps have been fastened to dead soldiers, fused to detonate when the body is moved.
(5) They have placed a dead Allied soldier in a conspicuous place and sited an automatic weapon to cover it. Thus, when Allied troops attempted to remove the body, they were shot.
(6) Even when badly wounded, or apparently dead, they have produced hand grenades from their clothing and attempted to kill medical personnel who would aid them.
(7) They have used the white flag of truce to get close to their enemy for combat purposes.
(8) They use firecrackers to simulate machine gun fire.
(9) They will expose themselves deliberately in an attempt to get their enemy to fire and thus disclose the location of his positions.
(10) In one case, a wave of Japanese skirmishers turned and fled. The Allied troops pursued and suddenly the retreating Japanese threw themselves on the ground. At this moment, heavy machine gun fire opened up on the Allied troops from the Japanese rear.
(11) They shake the bushes by ropes or other means in order to draw hostile fire and so locate gun positions.
1. Tactical principles in the jungle do not differ materially from those employed in open warfare. The technique or application of these principles, however, does vary, and the Japanese have taken advantage of this.
2. The Japanese use deceptive measures extensively and may be depended on to use ruses of all types to harass and deceive their enemy.
3. They stress the principle of surprise and employ it in the defense as well as in the offense. They do not disclose the location of their heavy weapons prematurely.
4. There is no such thing as impassable terrain, even in the jungle.
5. Japanese operations thus far have been characterized by inadequate artillery support, except in Malaya and the Philippines.
6. Speed is another cardinal tactical principle of the Japanese. They attempt to achieve surprise through rapidity of movement.
7. They take full advantage of natural cover and concealment, and thoroughly understand the importance of camouflage.
8. They believe strongly in the inherent advantages of vigorous offensive action, and often attack prematurely.
9. They have not made full use of supporting artillery.
10. Their organization of the ground and field fortifications are uniformly good.
11. On the defense their automatic weapons have very limited fields of fire, usually close in front of their position.
12. They will counterattack promptly when their position has been overrun, either by fire and movement or by fire alone.
13. They are hard fanatical fighters. On the defense they will often hold out to the last man. In the attack, once a plan of action has been decided upon, they will follow it through, even to a disastrous conclusion, since apparently they are unable or unwilling to readjust their plan.
14. They place a low value on human life and do not count the cost in taking an objective. Despite their extensive training and inborn confidence in the bayonet, they have not been outstanding in close combat.
15. The final conclusion to be drawn is: now that the Japanese have come up against forces in great numbers and units with unlimited resources of heavy equipment, their originally successful concept of jungle warfare, with their tactics based on surprise, mobility, and light equipment, has been shattered.
Section IX. SMALL ISLAND DEFENSE
1. GENERAL. The information in the following section has been obtained mainly from observations made before and during operations against Japanese island bases in the Central Pacific Area and also from detailed studies of these bases after capture by Allied Forces. Studies of the Japanese island bases, made before their occupation by Allied Forces, checked very closely with the defenses as found on the ground. The defenses of these islands are probably typical of those of other Japanese island bases in the Pacific.
2. TYPES OF SMALL ISLANDS. a. General. The small islands of the Pacific fall into two main classes: the coral atolls and the volcanic islands. Japan has established bases on islands of both of these types. The particular type of base set up has been dictated by terrain considerations, geographical location, and strategical necessity. Thus, not all of the Japanese bases in the Pacific are large ones and not all of them can be considered as supply and command centers.
b. Coral atolls. Coral atolls are small low-lying, generally oval-shaped rings of islets inclosing a lagoon which may run from about 2 to 65 miles in diameter. (See figure 101.) These islets may extend from a few yards to a mile in width and from a few yards to several miles in length. The total land area of an atoll may range from a few hundred
square yards to 6 square miles as in the case of Kwajalein, the largest known one. Atolls are rarely more than 25 feet above sea level, and, with few exceptions, are covered by dense growths of coconut palm, pandanus, and salt marsh. The water table is usually only a few feet below the surface of the ground, and, as a result of this, deep entrenchments and fortifications cannot be dug. A bomb crater generally fills up with water in a few hours. This limitation on excavations on coral atolls forces the defenders to build their fortifications above the ground in most cases and has resulted in the adoption of the bunker and pillbox type of fortification for atoll defense. The one exception to the above mentioned limitation is the antitank ditch. When these are constructed in low lying places they sometimes fill up with water and become a better obstacle. Some atolls have excellent large vessel anchorages in the lagoon (Kwajalein and Wotje), while others have no channel into the lagoon and only provide offshore anchorage, such as Uterik and Namorik.
Figure 101. Coral atoll.
c. Volcanic and raised coral islands. The Marshalls and Gilberts, and all but five of the Carolines, are coral islands. The exceptions are volcanic, or volcanic and coral. Some of the coral islands, such as Nauru and Ocean, are not atolls and contain no lagoons. These islands are large, circular, raised land masses and have been developed into bases by the Japanese. In common with the atolls they are surrounded by coral reefs.
d. Volcanic Islands. The volcanic islands of the Central Pacific have been developed into major bases by the Japanese. These run in a line from East to West as follows: Kusaie, Ponape, Truk, Yap and Palau. (See fig. 102.) These volcanic islands are much larger in size than the atolls and can support considerable garrisons. Most of the volcanoes are extinct, but some in the northern Marianas are active. Some, like Truk, are groups of islands. Truk is completely surrounded by a coral barrier reef located some distance off shore; and it contains a fine harbor and considerable anchorage space. Fresh water supplies are generally ample, and there is room on these islands for air-bases. The terrain is rugged and mountainous and is similar to some of the Hawaiian islands.
3. DEFENSE OF VOLCANIC ISLANDS. The defense of volcanic islands consists of beach positions, heavy naval guns up to 12-inch size, and mobile reserves. Beach defenses consist of observation posts, strong points, and obstacles, but these are not to be considered a perimeter defense. Large-sized units are held as reserves and are employed in counterattacking at threatened points. The defenders have the advantage of dominant observation, knowledge of the terrain, and large amounts of supplies. In addition to this, they have maneuver room, and if driven into the hills are quite capable of carrying out harassing operations for long periods. Airstrips are located on the volcanic island bases, and both land-based and naval aircraft are used in the defense. Antiaircraft artillery is used in the defense of harbors and landing fields. Army troops, as well as Special Naval Landing Forces, are likely to be encountered on these bases.
4. TYPES OF ATOLL ISLAND BASES. Some of the atolls have been developed into large airfields, while others are not large enough to contain an airstrip, and are used as seaplane bases where the aircraft use the lagoon as an anchorage and landing area. Others are not suitable for either of the above types of base and are used as weather stations and radio relay points.
5. LIMITATIONS ON SIZE OF GARRISONS. There is a physical limitation on the number of men that can be placed on an atoll in view of the limited space and the difficulties of fresh water supply. On most atolls, evaporators must be used to supplement the rainwater cisterns and the brackish water wells. The problem of supply and storage area also limits the size of garrisons. Natural food supplies on an atoll are very scanty, with
Figure 102. Map of Pacific.
the exception of fish, and since this is a staple of Japanese diet it is used a great deal to supplement the rations shipped in. Refrigeration is also a problem as foodstuffs spoil rapidly in tropical climates.
6. CORAL REEFS. All coral atolls are surrounded by reefs on both the ocean and lagoon sides of the islets. This is a great natural obstacle in favor of the defenders. In the Makin and Tarawa operations, certain landing craft could not negotiate the reef, and the landings therefore had to be made in amphibious tractors or by wading ashore several hundred yards in chest deep water. These reefs may extend from shore for a few yards or as much as a half mile. During high tide the reef is submerged below a few feet of water, while at low tide it may be completely exposed and above water. At low tide the reef makes a perfectly flat cleared field of fire for the defenders. As a rule no reef is found opposite the mouth of a river.
7. TYPES OF ATOLL DEFENSES. Two major types of defense are encountered on coral atolls: the perimeter defense and the fortified central area with outposts.
a. Perimeter defense. The perimeter defense is the one almost always used by the Japanese and is usually encountered on small islets in the atoll ring which are generally large enough only for an airbase. The landing field covers most of the islet, and the remainder of the installations are located around the field. Defensive works are a continuous band around the islet and are not generally in great depth. Practically all men are committed to the perimeter at the outset of a fight with few troops held in reserve. All types of weapons are on the perimeter, from 6.5-mm rifles to 8-inch naval turret guns. Trenches, pillboxes, barbed wire, mine fields, and antitank ditches are used in the defense. An example of the perimeter defense is shown in figure 103.
Figure 103. Perimeter defense.
b. Fortified central area. Another type of defense is used on islets which are long and narrow, or which are too long for the use of a perimeter defense with the amount of troops available at the time. The Japanese do not fortify the entire perimeter, but generally group their installations in a central area, build tank traps at the ends of the area, and install their defensive works behind the tank traps facing out. Small outposts are placed on the remainder of the islet, but there is no continuous line of defenses outside of those in the fortified area. The tank ditch apparently plays the most important role in the defense plan, since a great part of the defenses are arranged to keep attackers from penetrating that lute, and the majority of the pillboxes are located there. The heavier guns are placed near the shores between the tank ditches, since most of them are fixed guns and could not be used for close-in defense. The outposts generally consist of antiaircraft batteries and machine gun posts located at the extremities of the islets. A typical central fortified area is shown in figure 104.
8. DETAILS OF ATOLL DEFENSES. a. Antiaircraft defenses. (1) Early warning measures. The first evidence of Japanese radar in the Central Pacific was encountered early in 1943. While the performance of this equipment has not been up to accepted standards, improvement can be expected in the future. The extreme range of Japanese radar noted to date is 60-70 miles. The Japanese also make use of watchers as well as radio and weather stations on small undefended atolls as a means of passing early warning back to their defended bases.
(2) Antiaircraft weapons. In small islands encountered so far the only heavy antiaircraft guns definitely identified are the 75-mm (7-cm) antiaircraft gun and the twin-mount 127-mm dual purpose gun. These weapons are generally in two or three gun batteries and seldom in large groups. All weapons are well emplaced in heavily constructed revetments. The Japanese also have 20-mm and 25-mm antiaircraft automatic weapons. In the Gilberts 13.2-mm machine guns in single and twin-mounts were used. Automatic 7.7-mm and 6.5-mm guns are also used as antiaircraft weapons.
(3) Passive defensive measures. The Japanese have constructed heavy air raid shelters of palm logs, sandbags, and loose sand. On Makin and Tarawa these were extensively used during the bombardment by the Japanese troops, civilian laborers, and natives. Fox holes (weapon pits) and heavily revetted buildings also were encountered. Storage buildings and planes were dispersed as widely as the size of the islets permitted.
(4) Camouflage. Where used, camouflage is excellent, but is confined mostly to small weapons emplacements, antiaircraft guns, and alternate positions. Some buildings are dazzle painted. Great use is made of dummy installations in island defense and the Japanese take great pains in this. Most camouflage is obtained by the use of natural materials. (See figs. 105, 106, and 107.)
b. Anti-landing measures. (1) Obstacles and mine fields. The greatest obstacle in the attack of a small island is the coral reef which surrounds it. The reefs are found on both lagoon and ocean sides of the atolls and on the ocean side of other islands. However, there may be small stretches of beach on the lagoon side of the islets which are free of reefs and small stretches of reef-free beaches on the windward face of the ocean side of the islets. The Japanese have strengthened this natural obstacle by placing concrete pyramids (tetrahedrons), horned scullies, coral cairns, barbed wire, and log boat barricades on the reef. (See figs. 108, 109, 110.)
Interspersed with these is a mine field of waterproof mines containing a heavy charge of explosives detonated by a chemical-electric fuse. The detonating nipples of the mines are connected by wire to the obstacles and some also by wire to the shore. They can then be detonated by three methods: by direct contact, by hitting a trip wire, or by a pull wire from shore. Antitank mine fields also are placed on the beaches on both flanks of the antitank ditches. The reef is hard and will support medium tanks with ease.
(2) Pattern of fire and defensive weapons. (a) The defense of the beach is built around the machine gun and a final protective line. The beach defense usually consists of a shallow line of strong points, with a secondary line of lesser density located slightly to the rear. Because of the small size of the islands, depth of the defense is limited. The strong points consist of a group of bunkers and pillboxes connected by trenches and are covered by fire from riflemen in fox holes all around the installation. These fox holes are connected by communication trenches. The pillboxes and bunkers within the strong point are mutually supporting. Each rifleman protecting the pillbox generally has several alternate positions. He runs from one to another, and during combat this practice sometimes leads to an over-estimation of the strength of the defenders. The Japanese make extensive use of hand grenades in the defense of small islands, and flame throwers were present on Tarawa and Kiska.
(b) The Japanese defense of small islands is based on breaking up an attack before it reaches the shore, and all coast defense guns up to the 8-inch are sited so that they can be employed against small boats and landing vehicles. Batteries have local fire director control, generally 2 or 3 guns with observation towers at the gun position. Flat trajectory weapons predominate, with howitzer type weapons in the minority. These weapons are placed well forward on the beach where direct laying can be used against landing craft. Their grouping is shallow, all weapons being sited so that they can be used to repel a sea-borne invasion. This also applies to antiaircraft guns, the secondary mission of which is to repel surface craft and landing vehicles. To date coast defense guns found on these islands have
Figure 104 Central Fortified Area.
Figures 105 and 106, Examples of camouflage.
Figure 107. Example of camouflage.
Figure 108. Japanese beach obstacles.
Figure 109. Beach obstacles.
Figure 110. Beach obstacles.
ranged from 3 to 8 inches. The 8-inch guns were in turrets, while the 6- and 5-inch had shields. All were well emplaced in heavy revetments, with ammunition storage in covered emplacements close to the guns.
(c) All machine guns are sited to fire outward around the perimeter. Most of them are sited for cross-fire and cover the beach obstacles with enfilading fire. A few are also sited to fire to the rear of their positions. Some machine guns are in open emplacements, while others are set up in pillboxes. Those in open emplacements are generally dual purpose and have wide fields of fire; those in pillboxes have narrow fields of fire and are sited to fire only in one direction. All emplacements are protected by rifleman in foxholes and trenches around the installations. Some infantry regimental guns and battalion howitzers are used. Small use was made of trench mortars at Makin and Tarawa; however, this probably was so because of the limited number of such weapons in the Special Naval Landing Forces. Small arms used are both 7.7-mm and 6.5-mm caliber.
(3) Field fortifications. The Japanese defense of small islands is characterized by the extensive use of field fortifications. The bunkers and pillbox emplaced machine guns are the backbone of defensive fire. These fortifications have been developed from small installations, composed of a single layer of palm logs and sand bags and large enough for only a few men, into massive structures 6 to 8 feet thick, housing more than a squad. Palm logs are giving way to reinforced concrete and completely enclosed steel structures. These bunkers are relatively safe from damage by anything less than a direct hit by a 155-mm shell or larger. (See figs. 111-112.) The Japanese defend these to the last man, and some have been known to remain in these positions for days amid rotting corpses subsequently to come out fighting during mopping-up operations. (This was true at Tarawa and Makin.) A typical "bunker" and pillbox strong point protecting a coast defense battery is shown in figure 113.
c. Antitank defense. (1) Obstacles. To date the Japanese have constructed tank barriers only on the islets where there are airstrips and seaplane bases. These, generally, are antitank ditches and lines of obstacles. The ditches run from 4 to 8 feet in depth and from 10 to 20 feet in width. (See fig. 114.) They extend completely across the islet in the case of the central fortified zone and usually are protected by mine fields on the flanks. At communication points along these ditches the Japanese construct bridges guarded by palm log barricades filled with rocks. In the perimeter defense these ditches are found at the ends of airstrips and backing up critical landing beaches. Low palm log hurdles are placed in front of the ditches in order to slow up tanks approaching the trap. Concrete pyramids
Figure 111. Japanese field fortifications.
Figure 112. Field fortifications.
Figure 113. A typical coastal defense strongpoint.
Figure 114. Antitank ditch.
(tetrahedrons) and horned scullies are used on the reef as continuous barriers. Only very recently have the Japanese begun to use mines in defense of islands. On Tarawa a thick mine field was laid on the reef in the space between the tetrahedrons. On Kiska thin mine fields were found. On Makin several hundred mines were found in a warehouse, but none had been laid. Indications point to greater use of mines in the future.
(2) Antitank weapons. Although they possess more modern guns the Japanese so far have employed 37-mm rapid-fire guns in island defense. These guns are employed behind the tank barricades and ditches and are usually in open emplacements. Alternate positions are prepared for these guns, since the Japanese tactics are to keep antitank weapons mobile. Light tanks were included in the defense of Japanese bases recently captured, and the Japanese doctrine was to employ them against tanks landed by the attackers. All Japanese small arms are assigned the mission of firing against tanks and have done so in Pacific operations. Another antitank weapon is the magnetic mine which has been in use in all Pacific theaters.
d. Supply installations. (1) Japanese supply installations on small islands closely follow the principal of dispersion. Supplies are placed in small dumps, in many cases in shallow excavations, as a protection against bombing. Perishables and food are generally in warehouses, and refrigeration is used on some bases. With the increase in the size of island garrisons which has been apparent since the latter half of 1943, the Japanese have been placing a large part of their supplies on islets adjoining those on which their major defenses are sited. In the case of ammunition, the warehouses are connected by a narrow gauge railway. Causeways have been built between the islets to make communication easier.
(2) The Japanese also secrete small arms and ammunition in caches at various points on the islets, as at Makin, so that in case of a withdrawal from their fortifications they can fall back along their supply line. Canteen supplies, beer, and sake were plentiful, and there was no shortage of food. Supply vessels called at regular intervals. From most data available a level of supplies of about 6 months seems to have been maintained at all out-lying bases. Clothing supply was good. The Japanese in the Gilberts and Marshalls were all well supplied with food and clothing and were in excellent physical condition.
(3) The policy of reinforcing the island bases has been that each ship calling at a base drops off a few more guns and additional ammunition. The caliber varies, but each type of weapon is incorporated in the defense according to its capabilities. Ships bring supplies from central island bases or direct from the Japanese mainland.
9. AIRFIELDS AND SEAPLANE BASES. a. Types of airstrips. The type of airstrip used on the Japanese bases depends on the shape and size of the islet. On the circular islets the field is made up of two crossed strips. On crescent-shaped islets a triangular-shaped pattern is used. On narrow islets a single strip is laid. These patterns are fairly regular. Runways are surfaced with coral and have large turn-arounds at each end. The layout of the runways takes advantage of prevailing winds. Aircraft revetments are the palm log type, covered with sand. A new development has been the use of small railway cars loaded with logs and sandbags which, during an air raid, are rolled in place in front of revetments to serve as blast walls. Hangars are located on the service aprons and are of conventional design. The presence of underground hangars has been indicated on some bases. Seaplane bases are uniform in design, and generally consist of two concrete ramps extending into the lagoon, with a concrete apron on the shore bordered by hangars and machine shops. As a rule these seaplane bases are in the center of a fortified area.
b. Type of planes used. The types of planes encountered on small islands have been: four-engined flying boats; twin-engined medium bombers; land based pursuit; and single-engined float planes. The four-engined flying boat is used for long-range patrol work and now carries the brunt of aerial reconnaissance. Japanese interception tactics are normal.
10. SUCCESSIVE STAGES IN CONSTRUCTION OF BASES. Since the Allied offensive in the Central Pacific began, construction of air bases on most atolls long enough to support an airstrip has been noted. The first stage in construction of a base is building the airstrip. The antiaircraft defenses are next set up followed by emplacement of coast defense guns. Tank barriers and ditches come later, and pillboxes and bunkers last. The Japanese have used considerable numbers of civilian laborers in the construction of their bases. These laborers are not permitted to work on the defenses but only on the airstrips, barracks, and docks. They are carefully segregated from the Japanese military personnel and are not permitted access to the fortified zone. During the defense of some bases, they were given arms by the Japanese and were told to fight. Many did, while others merely hid in air raid shelters and then surrendered.
11. HISTORICAL EXAMPLE OF JAPANESE DEFENSE AGAINST AN AMPHIBIOUS ATTACK ON A CORAL ATOLL. a. Defense of Makin Atoll. (1) During assault phase. The Japanese used air attacks in order to break up the Allied assault before it reached the island. As the transport groups moved in for the landings the Japanese opened fire with every weapon available. During the initial landing small arms and automatic weapons opened up when the attacking forces came within range. They did not wait until troops got close in. Practically all of the defending troops were in the defensive works, and very few were held in reserve. They were unable to destroy or break up the assault or to prevent the establishment of beachheads. In the early stages Japanese defense was mainly by fire and very little by movement. Many remained in their bunkers and pillboxes until killed. During the first night the Japanese tried to infiltrate into the attackers' lines to reoccupy positions lost during the day's fighting.
(2) During mopping up phase. When their line of bunkers and pillboxes was breached, the remaining Japanese broke up into small groups and withdrew into covered areas, where they re-formed and then counterattacked. When these counterattacks were broken up, they formed into small groups to take refuge in bunkers, air raid shelters, and the salt marsh jungle. Japanese suicides were frequent during the mopping-up phase. Some remnants of their forces hid out for days after the fighting ceased, subsisting on coconuts and stolen rations, while others tried to escape out to sea. Probably because of the speed of Allied operations and the rapidity with which their positions were overrun, the Japanese were unable to destroy equipment and stores.
(3) Conclusions. Since the Japanese were unable to break up the Allied assault before it hit the beach and prevent landings, their beach strong points were overrun rapidly, and their defense plan was nullified. In order to counterattack they had to withdraw men from their prepared positions and thus lost the advantage of their fortifications. Their prompt counterattack was entirely in keeping with their normal tactical doctrine.
Section X. JAPANESE COASTAL DEFENSE
1. GENERAL. a. Scarcity of information. (1) Coast defense, as referred to in this section, is generally the method of defense adopted for large island and mainland areas, where defended localities are placed in strategic positions.
(2) The information on Japanese permanent or fixed coastal defense methods is very meager. However, thorough study of their training regulations, aerial photographs, and defensive measures carried out in the North and Southwest Pacific Areas as well as in Burma, present a fairly clear pattern of their methods for semi-permanent installations. As yet it is impossible to give a complete analysis of this subject, since it is only comparatively recently
that it has been possible to draw on active combat experience. Furthermore, it is to be expected that Japanese technique is not as yet fully developed, and changes will no doubt ensue. It is believed, however, that the general methods and defensive layouts described and illustrated herein will be of value in estimating the form coastal defense may take in the future.
b. Doctrine. (1) It must be borne in mind that the Japanese conception of defense is essentially offensive, consequently they do not envisage coast defense as a passive process of merely resisting a hostile attack, but rather one offensive in nature, whereby the enemy forces must be attacked and destroyed before landing or as close thereafter as possible.
(2) A natural corollary of this offensive attitude is the determination not to surrender, but to fight on to the last man and the last round. An excellent example both of this characteristic and of the offensive spirit was given by the Japanese defenders of Attu in the Aleutians. Here, after stubborn fighting, the defenders were ejected from their prepared positions, and those that remained were driven back and thrown into an obviously hopeless situation. However, rather than surrender, all of the able and wounded alike joined in a final desperate charge which was only stopped as the last of them was killed. This tenacity of the Japanese in defense must always be reckoned with when calculating the resistance to be expected from a coast defense position.
Figure 115. A cost defense position.
2. PERMANENT FORTIFICATIONS. a. General. The fixed fortifications of Japan proper are primarily coast defenses. Although very little information as to age or character of gun complement has been obtained, there are indications that some modern guns as large as 16-inch caliber are emplaced in some areas. Antiaircraft guns are included in the plan of defense.
b. Mission. The coast defense system is the second line of defense, designed to insure the security of the Empire, independently of the fleet. Defense zones are located throughout the main islands to guard strategic areas. Army and Navy aircraft act in concert in coast defense, although the primary responsibility 8is recognized to be that of the Navy.
c. Mines. Great reliance is placed on mining operations which are a function of the Navy. The Japanese envisage the extensive use of mines to cover the entrances of all approaches along their coast and to block entrances to the narrow seas between Japan and the Asiatic mainland. This inner edge of the mined area is to be patrolled by surface craft and aircraft from nearby fields to prevent mine sweeping operations. Inner mine barrages will be laid covering strategic points, and these will be covered by shore batteries.
3. ATTU ISLAND DEFENSE PLAN. a. Figure 116 shows that portion of Attu Island over which fighting took place during its recapture by
United States forces in the spring of 1943, and it also gives some idea of the mountainous nature of the terrain.
The Japanese defense plan for Attu Island seems to have been based entirely on the assumption that any Allied attack would take the form of a landing in the main bays and subsequent advance up the valley beds. The guns and positions covering the main northern bays were so sited and concentrated that landing craft would find it extremely difficult to reach shore while one gun still remained to fire. All positions were well emplaced, and the guns were secure against everything except a direct hit. In addition, in order to meet the contingencies that hostile naval fire and air bombardment might knock out the dual purpose guns, and a beach landing might be made, the Japanese had prepared almost unnumerable positions flanking the Holtz Bay beaches and facing inward and even to the rear. Behind the most inviting landing beaches they apparently had prepared 4 successive lines of resistance, with a final defensive line at the valley head. The setting for their plan was completed by the defense layout in Massacre Valley, where the lower positions flanking the valley were hidden by excellent camouflage, while those higher up were shrouded by the prevailing mist and clouds.
b. From the evidence of the siting of these positions, it is reasonable to assume that the Japanese appreciation of the course of the battle for Attu was that either a direct frontal assault would be made on the Holtz Bay beaches, or a back-door approach would be attempted via Sarana or Massacre Bays, the latter seemed more probable, for the exit from Sarana is blocked by Lake Nicholas. Their plan for Holtz Bay was designed chiefly to annihilate the attacking forces on the water or on the beaches and then to exterminate the few that might penetrate
Figure 116. Map of Attu Island.
into the valleys by concentrated enfilade fire. On the other hand, the apparent intention for Massacre Bay was to meet attack by more subtle means. Because of good camouflage and cloud cover, few positions in that area were likely to be located by previous reconnaissance, and the few visible tents, trails, and fox holes would suggest that the valley was only thinly out-posted. The few scattered soldiers who fled the beach at the approach of the attacking force may well have been a decoy to invite an advance up the bed of Massacre Valley. Against that march the enemy probably only intended to use enough frontal resistance to ensure the building up of a powerful force. When that force was pocketed in the valley, all the flanking machine guns and mortars would open fire, grenade discharger and rifle fire would plunge down from above, and finally the artillery at the head of the valley would complete the process of annihilation. The Allied Forces thus would be pinned to the ground and destroyed in detail by inferior forces having the two decisive advantages of concealment and absolute command of terrain.
c. The plan of defense for Attu failed, as do so many Japanese plans, because it made no provision for the unexpected. The direction of the attack of the Northern Force (shown on the map) took them by surprise and outflanked their carefully prepared Hotlz Bay position which lacked adequate all-round defense. The direction of attack of the Southern Force from Massacre Bay had been anticipated correctly, but not the nature of its execution which involved the quick movement ot high ground outflanking and dominating Japanese positions. The defense plan met some slight initial success, but was frustrated completely when Allied troops took the initiative by fire and movement tactics and promptly seized dominating terrain features.
4. KISKA DEFENSES. a. General. The garrison at Kiska was composed of Army and navy personnel in about equal numbers. Although a few Naval personnel were found at Attu, the garrison was composed almost entirely of Army men, and consequently the barracks, weapons, etc., were all of Army type. At Kiska the Navy was concentrated around Kiska Harbor, while the Army occupied the area around Gertrude Cove. Barracks and weapons of the Navy differed in some respect from those of the Army. In the future, particularly in the North Pacific Area, it is reasonable to expect installations similar to those in Kiska, where both the Army and Navy occupied different sections of the same island.
The Japanese development of Kiska was much more extensive than had been the development of Attu. Almost all beaches possessed some defenses including barbed wire and mines. In addition to the gun types found at Attu (75-mm and 20-mm AA, 75-mm and 37-mm Mtn. Artillery, and small arms), Kiska ordnance included 6-inch, 4.7-inch, and 76-mm naval CD guns, 25-mm and 13-mm (single and twin mount) antiaircraft guns, and 3 light tanks. Heavy machine guns in a few cases were mounted in concrete pill boxes. Passive defense included a radar installation, two 150-cm searchlights, and two 98-cm searchlights. Medical facilities were housed in well equipped underground hospitals.
In contrast to undeveloped Attu, Kiska, defensive areas were linked by a fairly well developed road net. Nearly 60 trucks, 8 sedans, 20 motorcycles, and 6 bantam-sized autos operated over this system. Two small bulldozers, tractors, and rollers were available for work on the airfield. The submarine base, the seaplane base, 2 machine shops, a foundry, and a saw mill complete the list of Kiska's special installations.
Water and power systems were well established at Kiska in contract to rather primitive systems employed at Attu. Power was provided mainly by 3 large power houses, but many additional smaller units supplied special buildings and outlying areas. Water from half a dozen small reservoirs was piped to installations and fire hydrants throughout the Main Camp area. Three complete radio stations, a radio-type navigation aid, and a well installed telephone system made up the communication network.
b. Beach defenses. For the most part the Kiska shoreline is lined by steep cliffs, with sand or gravel strips at the heads of the many coves which indent its bluff line. Exits from these gravel beaches are provided by steep stream valleys that rise abruptly between towering hills to the high central ridges of the interior. In emplacing his beach defenses the Japanese made excellent use of this naturally rugged terrain. Nearly all of the usable beaches at Kiska possessed at least light defenses, and in the island's strategic mid-section beaches that gave access to the built-up areas around Kiska Harbor and Gertrude Cove were strongly defended.
In general, Kiska beaches, which were accessible to landing craft, were mined; tank traps blocked possible overland exits; and barbed wire barriers were strung between breaks in the bluff line. From high ground at each of their extremities most beaches were completely covered by well camouflaged machine guns dugouts and rifle pits. In the hills behind these beaches other covered machine gun positions and trench systems with numerous fire bays commanded all possible exits along valley routes. At a few of the strategic coves single 75-mm and 37-mm artillery pieces were established in covered emplacements that commanded both the beach landing and its water approaches. in the more thickly settled areas like the Main Camp and the Sub Base the shoreline was honeycombed with dug-in machine gun positions, and in a few cases defenses were bolstered by reinforced concrete pill boxes.
5. THE DEFENSE OF A PROMONTORY. a. General. (1) The Japanese positions, shown in Fig. 117, have been located by aerial photography alone, therefore it cannot be assumed that the picture is complete in all respects. Sufficient information
Figure 117. The defense of a promontory.
seems to be available, however, to make clear the general pattern of defense, namely, the concentration of positions on the high ground so as to provide for coast defense, by means of fire power directed from well constructed positions on dominant ground, and to afford direct defense for the two landing strips. The exception to this principle is the siting of defense positions (Position B) close to the water line in the bay on the North-east of the promontory; this, however, can be explained by the relatively low-lying ground inland in this area, which necessitates the more forward placing of positions. It can be expected that many, if not all, the antiaircraft guns shown have been sited with a view to use in a dual-purpose capacity.
(2) There seems to be a similarity in the general defense layout between this system and that of Attu Island, except in the important point of camouflage. That little effort at concealment has been made in the present instance is clear from the amount that aerial photography has been able to reveal, whereas on Attu Island close attention was paid to camouflage and a good degree of concealment was achieved.
b. Development Area A. (1) Figure 118 illustrates the various stages in the construction of a defense position sited on a spur of high ground giving good fields of fire over the neighboring beaches. The locality is that shown at position (A) overlooking the main bay from the East at the north end of the promontory shown in figure 117.
(2) The earliest constructional activity consisted only of ground clearance, the marking out of the trench system, and a little preliminary digging. A month later the position was already fairly well advanced, for by then the trench system, up to a length of some 700 yards, had been completed, and 3 strong points had been incorporated in the general layout. The developments in the position which were seen to have taken place several months later are indicated as Stage 3. As can be seen, its defenses have been improved by additional trench digging, while a fourth strong point has been added, and wire defenses also have been erected. In addition, the communications have been improved by the making of a new trail into the position. In its final form, the locality can be deemed to be of good intrinsic strength, well sited, and designed to cover the beaches to the North and East.
c. Development Area B. (1) Fig. 119 shows the development of the position (B) as illustrated in figure 117. In its early stages the only really significant forward defenses were the pillboxes covering the length of the sea-front. Further back, a start had been made with the construction of defenses on the rising ground.
(2) At Stage 2, the position has taken its proper shape. It can be seen that the locality is sited in 2 'lines,' the first covering the sea-wall and its immediate sea approaches, while the second is set some distance back on rising ground having a good filed of fire over the flat terrain intervening between it and the sea-wall.
(3) Another interesting feature which has appeared at this stage is the extensive ditch, presumably designed as an antitank obstacle, which has been dug behind the sea-wall. This ditch is 15 to 20 feet wide and some 600 yards long. It should also be noticed that the most southerly defenses, which first appeared only as a ring of wire with a few isolated weapon-pits, have developed into an extensive light antiaircraft position, with ground defenses incorporated. This position is almost certainly sited to fulfill a dual-purpose role.
6. THE DEFENSE OF A BEACH-LINE. a. General (1) The system of siting defense positions as shown in fig. 120 of a coastal area in Burma is in evident contrast to that detailed in paragraphs 3 and 5. In this case, obvious emphasis has been laid upon siting defenses as far forward as possible. The frontal wire obstacles in places have been laid actually below the high water line, and the proximity of all the positions to this line is a very noticeable feature.
(2) Another interesting point of comparison between this layout and that of Attu Island is the extensive use made of wire obstacles and antitank ditches. In view of this, it is not unreasonable to presume that antitank mines have also been much more freely employed, probably both on the beaches and to cover the likely lines of approach of armored vehicles within the area.
(3) The relatively large number of strongpoints included within each defensive position is noteworthy. The majority of these are probably designed as fire positions for heavy and light machine guns, but some of the larger emplacements are designed to take heavier weapons, in particular the 37-mm antitank gun. This is a versatile weapon which has been freely used by the Japanese to fire against both landing craft and personnel, was well as in its original role.
(4) The siting of the central position, set back so as to enable it to cover by fire the rear of the forward positions, is of interest. It is presumably in this position, conveniently and centrally placed, that the local reserves would be held. Not also the similarity of this defense with the central fortified area described in Small Island Defense, Section IX.
b. Development of Area A. (1) The position shown in fig 121 is that marked as position (A) on the map of the beach defense layout (fig. 120). It is noteworthy for its speed of construction, since it reached the first stage shown in something under 3 weeks. During that time an extensive trench system was completed, 2 strongpoint were incorporated, and a long, forward zig-zag line of wire was erected. About a month later the locality had reached its final stage. By then, 4 new strongpoints had been constructed, a short length of communicating trench dug, and the wire defenses increased brought round to link up with the creek
Figure 118. Stages in the construction of a defense position.
on to which the position backs. A short forward length of brushwood also had been staked down in one sector.
(2) In general, this position may be said to be a typical example of the Japanese siting of a position for all around defense.
c. Development of Area B. (1) The defended locality illustrated in figure 122 (position (B) in the beach defense figure 120) was already at a fairly advanced stage of development when first photographed. Its chief interest lies in the number of strongpoints, eventually incorporated in it--no less
Figure 119. Stages in the construction of a defense position.
Figure 120. A beach defense layout.
Figure 121. Position A of beach defense layout as shown in figure 120.
Figure 122. Position B of beach defense layout as shown in figure 120.
Figure 123. Position C of beach defense layout as shown in figure 120.
than ten in a position with a total frontage of under half a mile. On of these strongpoints, added at a later stage as can be seen from the sketch, is noteworthy both for its exceptional size and for the fact that it is set right forward and not apparently connected with the general trench system.
In general, the position seems to be one of particular strength, and it is to be noted that, in addition to being covered on one flank by the antitank ditch and brushwood obstacle of the adjacent position described below, it is also covered on the other flank by a creed.
d. Development of Area C. (1) The locality here given in detail in figure 123 is that shown as Position (C) in figure 120.
(2) When first photographed, the defended locality consisted of a fairly extensive trench system with numerous firing bays and one covered strongpoint together with a forward zig-zag line of wire. It can be seen that during the second stage of development the position was extensively altered by the filling-in of a large portion of the trench system and by the adding of 2 further strongpoints and a short length of trench. In addition, a road was brought in to the north of the position.
(3) During the final constructional stages the locality underwent even more radical changes, one of the most interesting of which was the addition of an antitank ditch formed by canalizing a small creek. For a distance of about 400 yards, its banks were dug vertical, thus making an antitank position. A considerable trench system was also added at one of the later stages, which, as annotated in the sketch, is remarkable for the size of the strongpoint incorporated in it as compared with those in the rest of the locality. This particular strongpoint is of the double-bay type, in contrast to the more common single-bay variety. The defenses of the position also were strengthened by the addition of another obstacle in the form of a staked-down line of bushes sited well forward on the beach. This obstacle extends for nearly a mile, covers the whole front of the position, and links up with the adjacent defended locality described above.
7. TYPICAL SMALL BEACH DEFENSE POSITION. In figure 124 there is illustrated in detail a beach defensive position which the Japanese constructed in Burma. The zig-zag trench system, within wire defenses, consisted of 5 groups, inclosing irregular areas, separated by a tidal creek. The trenches were approximately 5 feet wide at the top, with firing bays projecting outwards, thus affording an all round field of fire. Approximately 66 bays, equally divided between the two areas, were constructed in the system at intervals, varying between 23 and 70 feet. A pillbox, about 10 feet square, was located within the northern trench system covering the stream. Both double and single lines of wire, set on posts at approximately 10-foot intervals, furnished obstacle protection to the area.
Figure 124. A typical beach defense position in Burma.
Figure 125. Use of artificial obstacles in beach defense.
8. DEFENSE INSTALLATIONS. a. General. (1) Japanese defense positions, both inland and coastal, generally include strong, mutually-supporting emplacements of a permanent or semi-permanent nature. The use of artificial obstacles has not been a universal feature. In various combat areas, however, there are indications that fairly widespread use is made of artificial obstacles for coast defense. This tendency can be expected to be intensified the more the Japanese Army is driven back on the defensive.
(2) Construction details illustrating obstacles have been taken from Japanese manual and training instructions and may reasonably be expected to represent their current practice.
Figure 126. A barbed-wire entanglement.
b. Obstacles. According to Japanese teaching, "obstacles are built to obstruct the enemy's advance and, combined with firepower, to destroy or hinder his movements, or to prevent surprise attack." They further state that wire entanglements and movable obstacles, combined with mines, abatis, and snares, normally are used. For antitank defense, ditches, mines, and obstacles for separating the infantry from their accompanying tanks are employed. The following details of their method are given:
(1) Wire entanglements. (a) In figure 126 there is illustrated the net-type wire entanglement. Not that both barbed and smooth wires are used in the construction. Except for the lower horizontal line, the Japanese stipulate that the wires need not be tight, but they stress that the efficiency of the obstacle is increased by stretching wires between the main wires to thicken the net.
(b) The double-apron type illustrated in figure 127 was found at Betio Island in the Central Pacific. Lanes sometimes are left between the lines of this type so that movable obstacles may be utilized. Here, again, both barbed and smooth wire are utilized
Figure 127. A double-apron type of barbed-wire entanglement.
(c) Passageways through wire entanglements are illustrated in figure 128.
(d) In New Georgia the Japanese used a prickly vine in lieu of barbed wire to form obstacles around defensive positions.
(2) Movable barriers. The Japanese feel that movable obstacles are not very effective, but realize that they are easy to transport, set up, and conceal. They are used when an obstacle is needed to surprise opposing forces, when concealment of positions is necessary, when closing up a passageway in an obstacle,
Figure 128. Passage-ways through barbed-wire entanglements.
to block roads, and where it is difficult to drive posts in rocky or frozen ground. The length and height are varied according to the tactical requirements and the convenience of transportation. The following three figures illustrate the type commonly used:
(a) Movable wire barriers.
(b) Cheval-de-frise (knife-rest) barrier.
(c) Spiral (concertina) barriers.
(3) Other types of barriers.
(a) Abatis. The Japanese recognize that abatis are easy to destroy, but they frequently use them in areas where trees are plentiful. Figure 132 show a type made by
cutting away the smaller branches of tree limbs, sharpening the ends of those remaining. The Japanese sometimes construct abatis by felling trees at a height of 2 to 3 feet from the ground; the trees, not completely cut loos from their stumps, are felled in the direction of opposing forces, and their limbs are prepared much in the same manner shown above.
(b) Folding screen. The frames are made separately and then connected as illustrated in figure 133. These may be used in rows.
(c) Wire snares. These may be of three types, illustrated in the following figures. It appears that either plain or barbed wire may be used, with the latter the most effective.
it is evident that snares are laid in "fields" at times on the principle of a mine field. In coast defense, they logically might be employed below the high water level, where they might well be expected to take attacking troops wading ashore by surprise.
(d) Example of the use of barbed wire. Barbed-wire defenses at Kiska were of four types:
Double apron (21/2-3 feet high at central and 10 feet wide).
Four strand fence (21/2-3 feet high--criss-crossed strands).
Low entanglements 1-11/2 feet off the beach designed merely to stall advancing troops momentarily.
Specially designed entanglements.
(1) Double apron fence predominated and was used principally to block the mouths of the stream valleys which at most beaches provide ingress to the interior. Usually, this fence was found erected along the slopes of grassy dunes just inland from the beach. In only a few cases was the wire established upon the beach itself. Pegs and posts used in stringing wire were of wood--apparently odds and ends left from building materials, etc.
(2) Four strand fence defenses were cleverly located at the crests of steep beach bluffs, where the barbs would retard the attacker after his energy had been spent in climbing. Heavy machine gun positions usually commanded the full length of these barriers.
- Low entanglements were stretched upon pegs just off the rocks of a few of the lesser beaches. in most of these cases the wire blended so well with rocks and sand that the observer could not see the barrier until he was within a few feet of it.
(a) At Reynard Cove a unique wire defense was set up in which the barbed strands were strung from the top of a 15 foot bluff behind the beach to pegs driven in the beach itself. This arrangement created a thorny maze of wire through which attacking troops would have had to climb in order to reach the high ground behind the buff.
(b) Barbed-wire defenses at Kiska were not set up in depth, however, and probably would not have hindered the attackers greatly. Except at 1 beach where 2 fences existed, no more than 1 wire battier stood between the sea and the island's interior. At many of the beaches unused coils of barbed wire observed in storage piles may indicate that further defenses were planned.
c. Defense structure. (1) General. (a) Japanese defense structures have not followed a set pattern to date, but have been made to conform as nearly as possible to the surrounding terrain and to meet the immediate tactical requirements. With some exceptions, these structures have been relatively
Figure 135. Japanese defense at Buna.
flat, extending 3 to 5 feet above the ground level, or irregularly shaped positions built around the bases of trees. A Japanese manual on field fortifications states that "it is most important not to adhere blindly to set forms in construction work, but to adapt such work to fit the tactical situation."
(b) When forced to take up an active defense, the Japanese apparently follow the theory that construction of defensive positions involves a continual process of development. First, the positions merely constitute a series of foxholes; subsequently, if time and circumstances permit, these are linked together to form a coordinated defense system. The third stage involves construction of strong points, bunker and pillbox types of earthworks, and log positions.
(c) Japanese positions have included bunkers, pillboxes, dugouts, shelters, blockhouses, rifle and machine-gun emplacements, fox holes, trenches, and antiaircraft emplacements and revetments. The terms "bunker," "pillbox," and "dugout" have been used very loosely,and it is sometimes difficult to do more than roughly differentiate between them.
(d) New Guinea. In New Guinea the Japanese terrain utilization between Buna Village and the coconut plantation at Cape Endaiadere was an excellent example of a complete defensive system. With the sea to their rear, they anchored their right flank on Buna Village where the unfordable Girua River and Entrance Creek enter the sea (Figures 135, 136 and 137), and their left flank on the sea below Cape Endaiadere. The built a system of bunkers with connecting trenches on all the high ground; this forced the attacking force to advance frontally along rather narrow corridors of dry ground or through impassable swamps.
(2) Bunkers. (a) Generally speaking, bunkers may be said to differ from pillboxes by their size, shape, and shallow foundations. Usually they have been found on a large scale only in those areas where high-water levels preclude the digging of deep trenches, and in more or less open terrain (for example, in coconut groves and on the edges of airfields.)
Figure 136. Japanese defenses at Buin.
Figure 137. Japanese defenses at Buna.
(b) Figure 138 illustrates typical bunker construction. The finished interior of bunkers varies from 4 to 6 feet in height, 6 to 10 feet in width, and 12 to 30 feet in length. The larger bunkers are found sometimes with 2 bays, or compartments, separated by a large solid block of earth. Each bunker has 1 or more narrow firing slits, difficult to hit even at close ranges. Thee slits are covered by some form of camouflage when not in use.
(c) In the Buna-Gona area, the bunkers and pillboxes (the latter have also been referred to as small bunkers) were built along the same general lines. With a shallow trench as a foundation, log columns and beams were erected, log revetment walls were constructed, and a ceiling then was made of several layers of logs, laid laterally to the trench. With the completion of this basic superstructure, the revetment walls were reinforced by such materials as sheets of iron, oil drums and ammunition boxes filled with sand, and additional piles of logs. Lastly, the outside was covered with dirt, rocks, coconuts and short pieces of logs. For camouflage, the surface was planted with fast growing vegetation.
Figure 138. A typical Japanese bunker.
Figure 139. Close-up of typical Japanese bunker.
Figure 140. Diagram of Japanese pillbox.
(d) Different types of entrances were used. Some had direct openings from fire trenches, while others had tunnels from the rear. With very few exceptions, all openings were constructed in such a way that the explosion of a grenade inside the entrance would not injure personnel inside the bunker.
(e) A few bunkers were used to shelter accompanying weapons such as antitank guns and therefore had large direct openings.
(3) Pillboxes. Usually Japanese pillboxes are constructed over, or near, dugouts, to which the enemy can flee for protection while being shelled or bombed. Some have been described as having front and rear compartments--the front part for firing and the rear for protection, storage of supplies, and rest or sleep. Some of the dugouts are 10 feet deep or more. Figure 141 is a front view of a typical pillbox. Note the narrow firing slit, cut at an angle to permit a wide field of fire, and the iron fasteners. Figure 142. shows how the inside of a large pillbox or shelter usually is constructed.
(a) Buna area. In the Buna area some of the pillboxes were made as follows: sand-filled oil or gasoline drums were placed at intervals in front of the trenches--enough interval was left to permit firing by automatic weapons and by rifles. Heavy palm logs were piled 3 to 5 feet in front of them
Figure 141. Front view of a pillbox.
drums, in such a way that they did not block the loopholes for firing. The structure then was covered with sod and otherwise camouflaged by shrubs and saplings, which were planted in a realistic manner.
(b) New Georgia.
(1) Many of the pillboxes n New Georgia consisted of two decks, which permitted personnel to drop through a connecting door during heavy shelling. All were described as mutually supporting and very well concealed. The pillboxes usually housed heavy weapons, while communication trenches leading out on the flanks generally concealed light machine guns.
(2) Coral rock, better than ordinary rock because it is more resilient, formed part of the protective covering on many of the New Georgia pillboxes (see fig. 144). It was used in conjunction with coconut logs, earth, and miscellaneous materials at hand. A large number of the pillbox tops had as many as four layers of coconut logs which were topped with dirt and coral rock. Ferns and growing shrubs were planted in the chins to round out a well-camouflaged appearance.
(c) Betio. Pillboxes--along with blockhouses, open and covered trenches, individual rifle emplacements, and open revetments--formed the main defensive system on Betio. They were situated within 100 feet of the high tide mark. The pillboxes were constructed mainly of reinforced concrete (several of these were 16 inches thick), coconut palm logs, and sand. Hexagonal (6-sided) steel pillboxes used as command posts, roughly in pyramidal shape, were found on all the beaches (see fig. 145), Apparently they had recently been installed, and were designed to be reinforced with concrete (concrete had already been placed around 2 of them). They had not been camouflaged, and were badly damaged, since most of them had not been reinforced by sandbags or coconut logs.
These pillboxes, apparently prefabricated, are designed to serve as command and observation posts. They have a double wall, between which sand and other material is placed for added protection. Apparently most of the beach-defense guns on Betio were emplaced in dugouts with overhead protection. Many of the dugouts were made of reinforced concrete. Figure 146 illustrates the concrete pillbox.
Figure 142. Inside view of Japanese pillbox.
Figure 143. Exterior view of pillbox.
Figure 144. A New Georgia pillbox.
Figure 145. A hexagonal steel pillbox.
Figure 146. A concrete pillbox.
Ammunition and supply dumps were scatted about the island in bomb-proof dugouts.
(d) Burma. (1) In general, the Japanese pillboxes in the jungle country of Burma were found to be similar to those in the South Pacific. The two types of structures for bunkers commonly identified in coast defense positions in this area are shown in figure 147.
The details of construction are as follows:
(2) The Double Bay type is built in 2 sizes, 25 feet by 15 feet and 60 feet by 40 feet. They consist of mounds of earth from 5 feet to 12 feet in height, with a rear entrance well recessed into the mound. Forward, a central, apparently solid, block projects to form 2 bays. These bays vary in size.
(3) The Single Bay type consists of a roughly circular mound of earth about 25 feet in diameter and 5 feet high, with an entrance at the rear opening into a crawl trench or the main trench system. In front is a firing slit; on, or slightly above, ground level, it is from 6 to 8 feet long and about 1 foot 6 inches to 2 feet high.
(4) The structures are designed for use by any of the weapons of the Japanese Infantry Regiment, but probably are best adapted for use by 37-mm antitank guns or heavy machine guns.
9. CONCLUSIONS. a. Pattern and principles. The tentative pattern and principles of coast defense which seem to emerge from study of the problems are: the Japanese may set their positions back from the coast line on high ground, with the intention of gaining complete control of ground and covering the beaches by fire alone, or if neighboring high ground is not available, their positions will be sited right at the water's edge with the intention of engaging any landing troops in direct combat at the moment most difficult for them. The selected localities will be well laid out and positions carefully constructed, while they will include a number of strong points with interrelated fields of fire. In comparison with inland defense positions, greater use is likely to be made of both anti-personnel and anti-vehicle obstacles, which may be of a variety of different types. Any artillery in the position will be boldly employed and sited, while its use in a dual-purpose role definitely is to be anticipated.
b.Tenacity. The Japanese conduct of the defense is characterized by tenacity and a determination to fight to the last man and the last round. As a corollary, any attacking force which gains a foothold in a Japanese coastal defense position must expect to meet concentrated and accurate fire from flanking strong points and must be ready to withstand an immediate and determined counterattack.
c. Weaknesses. The main weakness shown by the Japanese has been an inability to adapt themselves to the unexpected, and their coast defense position have been found particularly vulnerable to surprise, either in the nature or direction of attack. The Japanese also have shown themselves particularly
Figure 147. Types of bunkers.
susceptible to attack coming from ground higher than that on which their own positions were sited. Both these weaknesses were successfully exploited by the attacking forces on Attu Island.
1. GENERAL. a. Definition. Joint operations as discussed in this chapter are operations involving both Army and Naval forces, including air; transportation by sea and a landing on hostile shores are entailed.
Section XI. JAPANESE JOINT OPERATIONS
(1) Troop commander is the officer commanding all the forces which are to land.
(2) Convoy commander is the naval officer in charge of the movement by sea to the debarkation point. When there is an escort accompanying the convoy, the Escort commander is superior to the Convoy commander.
(3) Transport officer commands the special troops whose duty is to embark and debark the landing force. It is believed that this title is synonymous with that of Debarkation commander.
b. Purpose. Joint operations usually are employed for the purposes of seizing an island, establishing a beachhead as a prelude to future operations, or enveloping a hostile flank by sea. The principles of planning are essentially the same regardless of the purpose. Joint operations are usually large scale undertakings, although it is interesting to note the increased employment of the envelopment by sea, which may be attempted with a relatively small force.
c. Composition of forces. The size and composition of the force depend on the anticipated enemy strength, the terrain to be encountered, knowledge of defensive installations, and the scope of the operations. The force will include such special troops and equipment which are considered necessary to overcome anticipated difficulties. In some instances, a Special Naval Landing Party has been included to cover the landing of the Army troops.
d. Doctrine. Complete cooperation between Army and Navy is essential, the Army commander being given more responsibility in the operation than is awarded the naval commander. Secrecy, careful preparation, quick action, and deception also are prerequisites of success. Since landing operations are made under relatively unknown conditions, control and communications are difficult, and therefore all commanders should be ready to display initiative and to make individual decisions when instructions are lacking. Confusion can be expected with resultant demoralization. In view of this fact, troops must execute landing operations forcefully and with initiative in spite of bad weather, rough seas, persistent attacks by hostile planes and submarines, or strong enemy resistance.
2. RECONNAISSANCE AND PLANS. a. Reconnaissance. (1) Prior reconnaissance may result in loss of the element of surprise; nevertheless it is essential.
(2) Air reconnaissance of the proposed landing points must be made by competent officers who will participate in the landing. Aerial photographs showing the landing points both at high and low tides must be studied by all units.
(3) Reconnaissance from the sea must be carried out with secrecy. Submarines may be used, but their activities are limited by the depth of their draft and the limited view through their periscopes. Speed boats may be used, but care must be taken lest they disclose the plan.
(4) Although the method of reconnaissance will vary according to the mission, the time of day, and the equipment available, the following information should be gained at the earliest opportunity:
Topography, width, nature, and facilities of the beach.
Condition of surf at high and low tides.
Objectives and routes of advance.
Existence of airfields.
Correctness of existing maps.
b. Plans. (1) Based on the reconnaissance, the troop and convoy commanders select the anchorage and landing beach. Wherever possible, the beach selected should be one where enemy fortifications are weak. It should be so located that the plan of attack can be easily carried out, and it must be suitable for the landing of equipment. Alternate landing points should be selected in case the enemy situation or condition of the surf should dictate a change. When landings are to be made at more than one point, excessive dispersion must be avoided.
(2) The landing plan must have a margin of flexibility and must provide for delegation of authority so that rapidly developing situations can be met promptly.
(3) Plans must be worked out in every detail and all personnel be thoroughly familiar with them.
3. EMBARKATION AND REHEARSAL. a. Embarkation. The transport officer assigned to the convoy must carefully consider the troop commander's plan for landing. Based on this plan, he allocates space aboard the ships and prepares the order of loading. Extreme care must be exercised in loading the first wave so that its debarkation will be expedited. All materiel to be used by troops must be so loaded that it goes ashore in the correct sequence and at the time it is needed. If tanks are to be used with the first wave, they must be loaded on the same transport as the troops of that wave. Materiel should be so divided among the several ships of the convoy that the loss of any one will not seriously affect the success of the operation. If cranes will carry the load, boats and barges should be put over the side fully loaded.
b. Rehearsal. A transport which has completed loading will normally proceed either singly or in formation to the assembly point where it joins
the convoy. Rehearsals of the landing will be undertaken at the assembly point as a continuation of previous training. Since the time for this is limited, emphasis must be placed on the more important aspects of the landing. During the trip from the assembly area to the anchorage or debarkation point, all final arrangements will be made and instructions issued.
4. ACTIONS BEFORE LANDING. a. Transport commander's orders. At the assembly point, or immediately after leaving it, the transport commander will issue orders pertaining to the debarkation of the various units. These orders generally will cover the following points:
- Time for completion of landing preparations.
- Order of landing.
- Assignment of boats and barges.
- Hour of debarkation.
- Formation of ship to shore movement.
- Antisubmarine, antiaircraft, and anti-gas measures.
- Time for recall of boats.
- Communications between transports and beach.
- Rescue measures.
b. Responsibility of the convoy commander.
- Formation of the convoy.
- Communication between transports.
- Use of weapons for protection of the convoy.
- Care of casualties aboard transports while en route.
- Protection of the landing force. (This, it is believed, refers to naval gun fire covering the landing.)
- Formation of ships in the anchorage. They should be anchored parallel to the beach, and in single or multiple columns.
c. Other requirements. Landing units and debarkation units must complete all preparations for the landing the evening prior to arrival at the debarkation area. Commanders of all grades must be familiar with all details of the operation.
5. ACTION DURING LANDING. a. Timing. The landing should be timed so that the first wave will reach the shore just before dawn. If attack from the air, or an advance up a long defile is expected after landing, it may be necessary to start landing about midnight so that most of the personnel will be ashore by dawn. If the landing cannot be made at night or under cover of fog, a daylight landing may be necessary. In this case the landing should be covered by smoke, laid by the use of floating smoke candles. Transports may also fire smoke shells on important enemy positions such as observation posts and searchlights. (Fig. 148.)
b. Formation of landing waves. Generally all boats of each wave get under way at the same time. If the anchorage is at a considerable distance from shore, the landing barges may come shorewards in columns for ease of control and direction. In this formation, a certain amount of maneuver is possible so as to deceive the enemy as to the exact landing point. As the column approaches the beach it deploys and continues to the shore, regardless of hostile resistance.
c. Functions of work units. Work units from the debarkation troops are charged with the removal of underwater obstacles, marking the route for succeeding waves, construction of landing installations, rescue of men in the sea, salvage of damaged barges and when the occasion requires, they also act as combat troops.
d. Protection. The movement of landing craft from ship to shore should be protected against flank attack by the employment of armed barges, patrolling on the flanks.
e. Liaison, communication, and supply. (1) Liaison must be established between combat and debarkation units.
(2) Communication is maintained by the use of high-speed armored boats, radio, carrier pigeons, flag and lamp signals, and, when the anchorage is close inshore, by the use of submarine cables.
(3) Since the landing of supplies frequently is delayed, landing troops must carry extra food and ammunition. Supply dumps will be established near the shore as soon as possible.
6. ACTION AFTER LANDING. a. The first wave. The crucial time of the landing is when the boats reach the beach and troops disembark. The first units to land will deploy at once and immediately attack in full force to rout the immediate enemy and push inland. The first wave will secure the beach, and if necessary, dig in and hold till reinforcements land, at which time the offensive will be resumed. Bicycles and motor vehicles must be assigned to those units leading the advance or to reserves who will be used to exploit success.
b. Assault detachments. Each company commander should organize and have trained special assault detachments designed to neutralize fortifications and reduce centers of resistance by attacking them from the rear. Personnel of such detachments should land as a unit in one boat.
c. Feints. Feints may be used with success at appropriate times. These may be made through the employment of mine sweepers, aerial reconnaissance, bombing, ship's gun fire, by the routing of a transport to a false landing point, and even by making a temporary landing.
d. Supplementary landings. It is possible to assist the main landing by putting a unit ashore on a headland or difficult beach where the enemy is not expecting a landing. This unit can work around in rear of the enemy, attack his flank, and cut his lines of communication.
e. Artillery. (1) When naval gun fire is used to cover landings, care must be taken so as not to disclose the plans prematurely. The troop commander issues the orders for opening fire.
Figures 148 and 149. Smoke action during landing operations in eastern New Guinea.
(2) Part of the field artillery should be landed early to give direct support to the infantry near the water's edge. It is assigned the mission of neutralizing fire from fortifications and weapons protecting hostile flanks. Liaison must be maintained among artillery units so that fire may be coordinated. Positions for artillery should be chosen near the landing point but away from distinctive terrain features; they should be concealed from the air and inaccessible to hostile tanks. Infantry commanders give the accompanying artillery units assistance in changing positions or in moving forward.
f. Tanks. If tanks are used in the landing operations, they may be attached to front line battalions for employment at the water's edge, or retained for use in the attack at a later stage. If the situation dictates, the battalion commander must not hesitate to sub-allot tanks to companies.
7. NAVAL SUPPORT. a. General. In most landings that have been observed, naval units have escorted the troop transports to the point of debarkation and have supported the landing. During the earlier operations, naval vessels showed a marked tendency to leave the point of debarkation as quickly as possible, undoubtedly because of fear of hostile air attacks.
b. Naval gun fire. Naval gun fire in most instances has not been employed far in advance of the actual landing; the general practice has been to open fire on shore installations just prior to the hour of debarkation. At Kota Bharu, the naval gun fire did not commence until the troops had transferred from transports to landing craft. Fire was well placed and controlled.
c. Air support. In all Japanese landings first consideration has been given to neutralizing hostile air strength. Such effort has been highly successful in most cases, but at Kota Bharu the plan to destroy British planes on the ground failed, and, as a result, severe casualties were suffered. Japanese air has cooperated closely with ground units and has supported them well in the advance after the landing.
8. NOTES ON LANDING OPERATIONS. a. The Philippines. The principles of surprise and deception are well illustrated in the Japanese landings on the Philippines. A surprise air attack gave the Japanese quick control of the air. After this was secured, landings were made at opposite ends of the island of Luzon, the forces in each case comprising a special naval landing party and a reinforced brigade. Both landings were unopposed, and the forces at once began to establish beachheads, apparently to provide for the main landings which were yet to come. Each had naval escort and air support, and the landings were carried out rapidly and without confusion. When the main landings did occur, they were made on opposite sides of the central (narrow) part of the island, and although they were opposed, forces from the initial landings were able to put sufficient pressure on the defender's flanks to cause him to withdraw.
b. Kota Bharu. The landing at Kota Bahru in northern Malaya was made in 2 echelons. The first echelon, consisting of engineers, infantry, tanks, 37-mm guns, and mortars was to land and cover the debarkation of the remainder of the division. Under cover of darkness it entered the anchorage, supported by a squadron of heavy cruisers and 2 aircraft carriers. The Japanese knew that the beach was organized for defense and that their landing would be opposed. When the initial landing wave had been transferred to landing craft, the guns of the naval escort opened fire on shore installations, the first indication that a landing was being attempted. The first wave proceeded rapidly toward the beach and suffered heavy casualties, both from fire and from under water obstacles. Naval gun fire was well directed and finally concentrated on one portion of the beach where a few of the defensive guns had been put out of action. A channel was cleared through the obstacles to this beach, and succeeding waves, proceeding slowly and guided by the engineers, landed with few casualties. The Japanese reserves were used up in this landing, and their position would have been critical had not the main force arrived in the anchorage at that time and rushed reinforcements ashore. Planes from the carriers were assigned the mission of destroying British planes on the airfield, but, as a result of faulty timing, arrived over the target after the British had taken to the air. Japanese fear of hostile air was well founded in this case, as the few British planes caused heavy damage to the transports.
c. Both landing operations described here had been well rehearsed beforehand.
9. COMMENTS. a. The Japanese plan their landing operations carefully and issue orders complete in every detail.
b. Reconnaissance is thorough, and even small units are given maps and aerial photographs.
c. The army troop commander has more authority in the planning than the naval commander.
d. Landings are always escorted by naval vessels and supported by air.
e. Control of the air is regarded as necessary to a successful landing, and the Japanese have attempted to neutralize hostile aircraft in every instance.
f. The principle of surprise generally is employed in landing operations, either by concealing the time of landing or its exact location.
g. Deception, as in all Japanese tactics, is frequently used to conceal the location of the main landing or to land smaller forces at an unexpected point to assist the main landing.
Section XII. JAPANESE PARACHUTE TROOPS
1. GENERAL. Only small forces of parachute troops have been used by the Japanese in their operations during the current war. They have made only very modest claims for their achievements and early realized that considerably more thought must be given to the training and organization of these forces.
2. EMPLOYMENT TACTICS. a. Palembang. At Palembang, Sumatra, in February 1942, Japanese parachute troops were assigned a two-fold mission; to gain control of the airfield at Palembang; and to seize the 2 large oil refineries there before they could be put out of commission by the opposing forces. The airfield and the 2 refineries were so widely separated that the battalion (about 700 men) was divided into 3 combat teams, each of which had to operate independently and out of support distance of the units attacking the other 2 objectives. The force used appears to have been too small to accomplish the missions properly. However, even though the parachute force was practically destroyed, and the entire operation was characterized by the utmost confusion, the effort served the Japanese well as a training maneuver. It also served as an effective diversion (possibly unintentional) while the Japanese were moving in from the sea to take Palembang.
b. Timor. On Timor Island, in June 1942, parachute troops were employed by the Japanese on two successive days, during sea borne landings, to cut the communication lines of the defending forces. The operation is described as follows: Twenty to 25 troop carriers came in supported by bombers and fighters. The bombers operated in groups of 9, in arrow formation. It was estimated that each carrier contained from 15 to 25 troops, which were dropped in groups of 6 to 8. There was no wind when the operation took place at 0830, in bright sunlight. The objective on each occasion was a position astride the hostile line of communication. The area chosen was fairly level, but timbered with high palm trees from 15 to 20 feet apart over certain portions, with thick undergrowth in the adjoining areas. There was no air opposition, and the objectives were from a mile and a quarter to a mile and three quarters from the nearest company outpost area and about 5 miles from the main defenses. Japanese paratroops landed from a low altitude, estimated to be 300 feet. During descent automatic weapons were fired, and considerable noise was made. While the landings were being made, the escorting planes bombed and machined gunned the defending positions. The paratroops, upon landing, quickly took up ambush positions; some climbed trees from which they acted as snipers. Forward positions were marked with Japanese flags, to facilitate their quick location by aircraft, and alternative positions were used extensively as soon as each squad was fired upon or outflanked. It was the use of these troops which prevented the withdrawal of the relatively small defending garrison which was opposing a landing of a large Japanese force in the Koepang area, since the paratroops had cut off the line of retreat.
c. Central China. In November 1943, in the Tungting Lake Campaign, in Central China, it was reported that the Japanese used parachute troops in the attack on Taoyuan, Hunan. Previous to this attack the Japanese carried out a thorough air reconnaissance of the area and subjected it to heavy strafing before dropping the troops. During the landing of the troops, made on elevated ground, the Chinese positions were kept under constant bombing and strafing attack from low flying planes. It was estimated that approximately 60 men were dropped, all landing near their objective. The leader of the force fired a flare which was apparently a signal for plain clothes men in the city to aid the attack. The parachute troops collected their equipment, which had been dropped first, and organized for the ground attack in approximately thirty minutes after landing.
3. CONCLUSION. The Japanese Army no doubt has acquired the practical appreciation of the value of parachute troops and the proper methods for their employment, although they have used them only in a limited capacity. The Japanese must also realize that the successful employment of these forces is contingent upon air superiority and absence of ground troops in the areas in which they are used. This assumption, however, should not be given too much weight when gauging expected Japanese action, even though they might lack air superiority. It must be borne in mind that this type of troop employment is in keeping with Japanese principles of surprise and their spirit of sacrifice, and it is reasonable to assume that a parachute troop attack may be attempted by them even though air superiority is not established.
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