Paragraphs Section I. Targets and fire missions 151-157 II. Characteristics 158-166 III. Requirements in guns and ammunition 167-171 IV. Coordination of fire 172-175
Targets and Fire Missions
- Characteristics of defense Positions.--
- To plan the artillery fire support for a landing operation, it is necessary to understand the characteristics of a defensive position. these characteristics are similar for either a coast line or an inland position.
- Defensive fires may be opened initially at maximum ranges of the weapons, and thereafter maintained on the approaching boats or troops. The fires which may be expected immediately in front of a defensive position are shown in zone X, figure 16. This zone may be along and immediately to seaward of the beach or in front of an inland position. A heavy concentration of fire of all types of weapons may be expected on the ground or water over which the attacking troops must advance.
- The bulk of the fires in zone X are delivered by rifles, automatic rifles, machine guns, and antiboat or antitank guns, located in or near the enemy front lines, and capable of delivering direct fire upon the approaching boats or troops. Some field artillery weapons may be located in zone A for the purpose of executing direct fire on small boats approaching the shore and delivering enfilade fire on critical sections of the beach. Some large caliber artillery weapons may also be well forward to execute fire on transports while they are unloading men into small boats. Zone A, in which these direct-fire weapons are located, may extend a distance of several hundred yards in rear of the enemy front line, depending upon the terrain, but those located close to the front line are the more dangerous to the attacker.
Figure 16.--Defensive position.
- Zone B contains the rear defensive lines, and may extend as far back as 2,000 yards from the front line. Machine guns and mortars located in this zone support the front line by indirect fire. if the front line is disrupted, machine guns in these rear positions change to direct fire, and rifles and automatic rifles which had previously been masked may become
effective. The rear position then assumes some of the characteristics of the front line position illustrated. For example, other zones similar to zone A might be developed along the general line: a-a-a, or b-b-b. Machine guns employing overhead fire from zone B are not as dangerous to the initial attack as those employing grazing fire from the vicinity of the front line; but the fire of mortars and antiboat guns located in zone B is particularly dangerous.
- Zone C contains the bulk of the artillery and for calibers of 155-mm or less normally extends about 6,000 yards in depth from the beach. This artillery supports the original front line. In case of a break-through of the front line it supports positions in rear such as the line a-a-a, or b-b-b.
- Infantry supported by artillery and other available means defends the position by a combination of fighting in place and counterattack. Thus, in addition to the hostile troops initially in position in zone A, important targets are reserves in rearward positions or moving forward either to take up a defensive position or counterattack. Other targets are command posts, observation posts, centers of communication, ammunition dumps, and other facilities used by the enemy for command or administrative purposes.
- Fire Missions.--Types of fire missions assigned naval fire support groups are supporting fire, counterbattery, interdiction, destruction, harrassing fire, fire on targets of opportunity, and countership fire.
- Supporting Fire.--
- Supporting fire is delivered on the enemy defensive position to neutralize personnel and matériel most dangerous to our own infantry in overcoming resistance. The Navy has two classifications: close supporting fire, delivered initially on the beach and lifted as the attack progresses to positions to be assaulted; and deep supporting fire, the principal objective of which is to deepen close supporting fire by neutralizing reserves and weapons firing from rear positions and disrupt the hostile command, communication, and observation system.
- Close supporting fire, being difficult for naval guns to deliver, is reinforced by aviation, boat guns, inshore support vessels, and by tanks and artillery of the landing force.
- Interdiction Fire.--Characteristic targets for interdiction fire are roads used for moving reserves or supplies and areas where military or naval work is in progress. Suitable points to be fired upon are crossroads, assembly places, detraining points, defiles, bridges, and fords.
- Destruction Fire.--Fire for destruction by naval guns requires considerable time, a heavy expenditure of ammunition, and continuous observation. In landing operations, destruction fire by ship guns is usually limited to targets of limited areas which are visible from seaward. Such targets are particularly dangerous machine-gun and antiboat gun emplacements, important bridges, or coast and field artillery weapons, including antiaircraft weapons, located close to the shore.
- Fire on Targets of Opportunity.--Fire on targets of opportunity may include enemy troops forming for counterattack, working parties, troop or train movements, batteries of artillery, and troops preparing or occupying a defensive position not previously located.
- Countership Fire.--Countership fire is delivered on enemy vessels which attempt to interfere with the landing operation.
- Artillery support, at least in the initial stages, is furnished by naval gunfire exclusively. Detailed joint planning by the Navy and Army attack force commanders is required, including liaison and signal communication between advancing troops and their supporting artillery.
- Naval artillery has a high velocity and a flat trajectory. Objectives selected for naval artillery should be large, well defined, and farther ahead of our infantry for safety reasons than is usually the case when field artillery support fires are employed, The limited supply of ammunition available for all types of naval guns prevents the firing of barrages and firing on minor or suspected targets. Naval artillery support is usually by short concentrations fired according to a prearranged
schedule on targets visible from the firing ships, from observation points on land, or from spotting aircraft. Provisions are made for firing on targets of opportunity. Map firing is employed only as a last resort, but a liberal use is made of maps in the designation of naval artillery objectives in the plan of fire support.
- If naval antiaircraft guns are not required against enemy air operations, they may be used advantageously against shore objectives.
- Gunfire support begins with preparation and continues through successive stages of the landing operation. During the time the troops are disembarking from the transports into the leading boat groups and until the leading boats reach the beach, fire is placed normally on known hostile artillery positions, organized strong points, machine-gun nests, defiles on routes over which supports and reserves must pass and, generally, on objectives the neutralization of which will weaken the enemy's defense. Naval artillery support plans provide for effective fire on the beach to cover the movement of the leading waves ashore. Just before our troops reach the shore, fire is lifted to targets farther inland. The terrain beyond the beach influences the distance the fire is lifted.
- Two general methods are employed by naval forces in affording artillery support where two or more landing forces land simultaneously. One is to keep all firing units centralized under the highest commander; the other is to decentralize naval support groups to support subordinate Army nits. The following are examples of the second method. When two infantry divisions land simultaneously and the naval units have been divided into two naval attack forces, it may be desirable to--
- Have the naval vessels of one naval attack force support one division, and the naval vessels of the other naval support force support the other division.
- Divide the naval force into three supporting groups, one group being assigned to support each division and the remaining group to support the operation as a whole.
- Make a division by calibers, the large caliber main batteries of large ships being assigned to general support while the smaller caliber secondary batteries are assigned to support subordinate units.
- Factors Involved.--The suitability of naval gunfire for supporting shore operations is influenced by muzzle velocity and trajectory, pattern, type of projectile and fuzes, direct fire, indirect fire, ammunition supply, and mobility.
- Muzzle Velocity and Trajectory.--High velocity fire is effective on targets on a forward slope and has a demoralizing effect on the enemy. The disadvantage of the flat trajectory of naval artillery against a reverse slope may be overcome by selecting a location from which naval weapons may bring fire to bear from a flank or rear firing position.
- Pattern.--Naval gunfire has a relatively large pattern and is not as well suited for the close support of infantry as fire support furnished by the field artillery.
- Types of Projectiles and Fuzes.--Armor-piercing naval projectiles have a delay action fuze; common projectiles have an instantaneous fuze. Both projectiles have a smaller bursting charge than high explosive shell of the same caliber employed by the field artillery and are not well suited for general use in support of a landing. Flat-nose, antiaircraft, and bombardment projectiles compare favorably to field artillery shell, and should be made available for the bulk of the supporting fires. Shrapnel is infrequently used by the Navy.
- Direct Fire.--Against a strongly defended coast line, the greatest danger to the immediate landing is the fire of rifles, automatic weapons, and antiboat guns located on or in the vicinity of the beaches and capable of delivering direct fire on landing boats and disembarking troops. These weapons are difficult to discover and locate accurately. Ordinarily, they will not open fire until the boats are close to the beach and after offshore ships have ceased firing, or lifted their fire inland. Inshore supporting vessels, protected by counterbattery fire from offshore groups, move in close to the shore. This facilitates picking up targets when the enemy opens fire and permits the supporting fire to be maintained closer to boats and troops.
- Indirect Fire.--
- Indirect fire is generally more difficult to deliver from ship guns than from field artillery weapons. Its accuracy depends largely upon continuous air or
surface observation, or exact plotting of the position of the ship and target at all times.
- It may be possible, particularly when attacking small islands or peninsulas, to select firing positions for the supporting ships which will obviate to a great extent the necessity for indirect fire.
- Missions which necessitate particularly difficult indirect fire should be assigned to aircraft.
- Ammunition Supply.--
- The relatively small magazine capacity aboard ship and the necessity of keeping combatant vessels and aircraft prepared for fleet engagements limit the supply of ammunition for the support of a landing.
- Second line combatant ships, suitable Coast Guard vessels, and converted merchantmen are utilized to the fullest extent to provide gunfire support.
- Mobility.--The mobility of ships permits flexibility in the employment of naval gunfire. Advantages of this mobility are--
- Inshore supporting vessels can move in with the landing boats and engage the beach defenses at short range.
- The fire of several ships can be concentrated successively in support of landings at different beaches.
- A wide choice in the selection of firing positions for the execution of particular fire missions is possible.
- Protection from enemy submarines, aircraft, and shore artillery is afforded.
In developing the scheme of maneuver and planning the fire support for a landing operation, advantage is taken of these characteristics.
Requirements in Guns and Ammunition
- Fire Support Requirements.--
- Destruction of a major portion of enemy personnel, weapons, and field works by naval gunfire is seldom practicable because of the expenditure of ammunition required. Sufficient fire is provided to cause the enemy to cease firing and to take cover. This fire is maintained long enough to reduce the enemy resistance to the extent that he can be overcome by attacking infantry.
- In firing over a considerable period of time, the best results are obtained by firing several bursts with varying intervals between each burst. This leaves the enemy in doubt as to when the bombardment has finally ceased and makes him hesitate to rush from his shelter to his combat stations.
- Once the enemy is under cover, he can be kept there with less density of fire. It is advisable to open with an intense bombardment and then reduce the rate of fire. For the last few minutes of fire, every gun of every caliber which can be brought to bear fires at its maximum rate in an attempt to make the bombardment overpowering.
- If the time interval between lifting fire and the attack of the defensive position is greater than 2 minutes, the density of fire is increased accordingly. Another essential element considered is the ability of the attacking troops to make use of their own weapons immediately before and after the naval artillery fire lifts. During the approach to the beach, the fire from boat guns replaces the fire of troops in land warfare. The volume of fire from this source is increased by all possible means. The use of small boats permits more guns to be brought into action. Accurate laying on specific targets is not expected, and it is often more desirable to spray the whole area with machine-gun bullets and high-explosive shells. This fire is provided for the purpose of keeping the enemy under cover until the troops can disembark and make use of their own weapons.
- Requirements for Close Supporting Fire.--
- Close supporting fire, particularly that delivered immediately prior to the assault, should reach a density equivalent to sixteen 75-mm shells per minute per 100-yard square. Just prior to a landing this density is maintained on the enemy defenses at the beach, and a minimum density equivalent to eight 75-mm shells is extended inland to engage weapons from which direct fire may be expected. In planning close supporting fires, target areas are shown preferably on a map or air photograph.
- The routine of fire is varied as to the length and number of bursts and the interval between them. The following naval fire schedule is an example.
Time Percentage of total ammunition fired First 3 minutes 331/3. Next 5 minutes None. Next 10 minutes 331/3 (with 1 minute of rapid fire). Next 3 minutes None. Next 3 minutes 331/3. Total period: 24 minutes.
- The final burst of fire is of sufficient duration to enable it to start before the landing boats arrive within effective small-arms range of the beach and to continue until the boats are about to enter the beaten zone.
- If inshore supporting groups are to fire during the same period as offshore groups, the total number of shells fired by both groups is the basis for the computations. Sufficient ammunition, however, is provided to enable inshore ships to maintain their maximum rate of fire during the close approach of the boats and to cover the flanks of the advance inland.
- When inshore vessels can approach close to the beach the fire, shell for shell, is more effective than that of offshore groups because vessels firing at short ranges will probably be able to locate enemy weapons, and maintain a heavy concentrated fire on them until the boats are practically beached. Under these conditions, inshore vessels do not have to deliver as great a density of fire over the whole area as offshore ships to produce the same effect.
- Requirements for Other Fire.--In a similar manner, the Navy determines the density and ammunition requirements for deep supporting fire, counterbattery, interdiction, and destruction.
- Fire Support Groups.--The ships assigned the task of furnishing gunfire support for a landing are organized into one or more task organizations, and given designations such as Fire Support Group ONE, Fire Support Group TWO.
- Fire Support Areas.--
- Fire support areas are located to avoid the employment of indirect fire. Close supporting fires on the beach are invariably provided by direct laying.
- Advantage is taken of flanking fires, particularly in delivering
supporting fires on the beaches, and in positions sited on reverse slopes or otherwise defiladed. The location of fire support ships on the flanks permits more room for the movement of the boats, their fire is more demoralizing to the enemy, and boats or troops on land can approach closer to the area being shelled before it is necessary to lift the fire.
Section IVCoordination of Fire
- Cooperation Between Army and Navy.--
- Complete plans for gunfire support are made prior to embarkation by the commanders of the naval groups which are to give the support and by the commanders of the respective Army units they are to support. Commanders of Army units indicate the objectives upon which they desire fire, the purpose of the fire, and the times they are to be fired upon. The naval commander concerned indicates exactly how much of the desired support he can give. in case the Navy has not sufficient guns to provide the minimum artillery support desired, every effort is made to secure additional ships or to provide the support by means of combat aviation.
- Plans include provision for the interchange of liaison officers between Army and Navy nits. Officers of artillery organizations which do not debark initially may be used for the purpose. All liaison officers report to the headquarters to which assigned in time--normally prior to embarkation--to become familiar with the other service and to be able to interpret the desires and needs of the commanders of the units whom they represent.
- Coordination of Close Supporting Fire With Movement of Boat.--
- Observers on Navy ships engaged in fire support watch for signals from the control vessels and boats. Ships open close supporting fire when the leading boats are in the position prescribed by the attack force commander rather than on the time schedule. About 15 minutes prior to the arrival of the boats in this position, the control vessel concerned informs the commanders of the naval attack force and the fire support group the exact time the boats are expected to arrive at the prescribed position. This gives the fire support group sufficient time to get into the position
selected for opening fire. If control vessels are not with the leading boats, it may be advisable to designate an observing plane to transmit this information.
- Firing ships observe or are informed when the leading boats leave the line of departure. Plans are made to cease or lift the fire a designated number of minutes after the line of departure is crossed. This will be the running time of the boats from the line of departure to the danger zone of supporting ships' fires. As it is important that the boats approach as close as possible to the area being shelled before the fire is lifted, the movement of the boats is observed and the fire maintained on the beach as long as practicable.
- Boats are furnished pyrotechnic signals to signal that the fire is falling short or should be lifted.
- The distance the fires are lifted ahead of the boats depends on the range, pattern, visibility, caliber of supporting guns, character of aiming points, roll and pitch, and the direction of approach of the boats in relation to the line of fire. Fragments may be considered dangerous to friendly troops and boats at the following distances from the point of burst:
3-inch, 150 yards.
4-inch, 250 yards.
5-inch, 400 yards.
6-inch and above, 500 yards.
- Coordination of Naval Supporting Fire With Landing Force Artillery.--
- After the field artillery is ashore it takes over the fire missions of naval supporting groups as rapidly as possible. Normally, the first fire mission to be taken over by artillery ashore is that of close supporting fire, as this is the type of fire most difficult for naval guns and for which light field artillery is best suited. Because medium or heavy artillery will probably not be available, particularly during the early phases, and light artillery may be limited in amount, naval guns may have to continue deep supporting fires, counterbattery, and interdiction during the attack on shore.
- Field artillery executes the close supporting fire generally on call from the liaison officers with the front line infantry battalions. Naval fire support groups are advised of the expected rate of advance of the infantry. This predicted
rate of advance, together with current reports from field artillery liaison officers, permits the fire support ships to displace their deep supporting fire the proper distance ahead of the close supporting fires of the field artillery.
- Coordination of Naval Supporting Fire With Aircraft.--
- In planning fire support of a landing, available aircraft should be used to take over and supplement the gunfire missions. Missions most suitable for assignment to aircraft after local control of the air is assured are--
- Attack to destroy and demoralize beach defenses.
- Close support of the infantry immediately prior to the landing and during the advance from the beach.
- Attack of hostile reserves, especially armored units.
- Interdiction of roads, particularly those lying a considerable distance from the coast and not visible from seaward.
- Counterbattery on batteries difficult to reach by naval guns.
- Usually there will not be sufficient aircraft to carry out all of the missions desired. First consideration is given to those missions directly supporting the landing and the immediate advance from the beach.
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