Plans and Preparations
As early as September 1943, the Joint War Planning Committee in Washington formulated preliminary plans to seize the Bonin Islands.1 Planners realized that after the fall of the Marianas the Bonins would constitute a vital point in the intermediate defense of the Japanese homeland. And since these islands were traditional Japanese territory, administered as part of the Tokyo Prefecture, their loss would be a tremendous psychological blow to the Empire. In spite of the dearth of intelligence information at that time, planners correctly foresaw that the terrain favored the defenders and that the operation would entail heavy losses for the attackers. Iwo Jima was singled out as being one of the most vital objectives in this group.2
These early plans were consonant with Army Air Force desires to seize Marianas bases for the new long-range bombers, which were then under discussion at high-level conferences. By March 1944 the Marianas operation was definitely scheduled for 15 June, and the over-all objective of the Central Pacific Forces became clearly outlined. The mission was now essentially twofold: (1) to secure control of sea communications by neutralizing the Carolines, and (2) to establish sea and air bases for operations against Japanese sea routes and for long-range air attacks against the home islands of the Empire. All Central Pacific Force planning was now predicated upon the decision to capture the Marianas.3
Lying midway between the Marianas and Tokyo, directly athwart the route to be followed by our very-long-range (VLR) bombers operating from the Marianas, the Volcano-Bonins became of major strategic importance. Consequently, the Army Air Force became intensely interested in an operation designed to seize objectives in this area. Such an operation, however, was not to be executed until the Marianas were secured for B-29 bases. Fighter strips would then be required from which long-range fighters could escort the big bombers in their sorties northward from the Marianas to Japan.4
By mid-1944 the conduct of Pacific operations reflected much more than an effort to seize
islands, naval bases, and airfields. Campaigns were listed as follows:
Code Name Operations Tentative
FORAGER Capture of Saipan, Guam, and Tinian 15 June 44 STALEMATE Capture of Palau 8 Sept 44 INSURGENT Occupation of Mindanao 15 Nov 44 CAUSEWAY Capture of Southern Formosa and Amoy or 15 Feb 45 INDUCTION Capture of Luzon 515Feb45
Seizure of these objectives would place American forces in position to tighten an iron vise around the heart of Japan. Then United States military and naval might would be poised to launch attacks on the home islands.
At the end of June a paper entitled "Operations Against Japan Subsequent to Formosa," listed an advance from the northern Marianas into the Bonins as a possible step following the Formosa operation, the tentative date being April 1945.6
In line with concepts contained in the above reference, the Joint War Planning Committee completed a plan for the seizure of the Bonins and submitted it to the Joint Staff Planners on 12 August 1944. This stated that seizure of the Bonins could be conducted as a highly desirable "operation of opportunity" for:
- Providing fighter cover for application of our air effort against Japan.7
- Denying these strategic outposts to the enemy.
- Furnishing air defense bases for our positions in the Marianas.
- Providing fields for staging heavy bombers against Japan.
Iwo Jima, planners contended, was the only practical objective in the group. It was the only island that could support a large number of fighter aircraft, and its topography appeared to render it unusually susceptible to preliminary softening by aerial and surface bombardment with full benefit of advance aerial and submarine reconnaissance.8
The seizure of the Marianas was executed as planned. Tinian and Guam had been taken by the end of August and the way cleared to construct B-29 bases on these islands. The heavy attrition suffered by enemy air power throughout the theater, as well as the reduction of once powerful garrisons, convinced the American high command that our forces could overcome enemy resistance on any island position in the Pacific. This confidence was based on the fact that we could not concentrate and coordinate the combined power of all available naval, amphibious, and shore-based air forces in any concerted operation that might be necessary.
An operation in the Volcano-Bonin Islands, which fitted neatly into the big picture, was now more than a mere possibility: the question became "when" rather than "if." In a study of naval personnel requirements for the Pacific Theater through 30 June 1945, the Joint Staff Planners presented the Joint Logistics Committee with a list of projected operations as well as the number of divisions needed in each instance. In this study three divisions were specified for the Volcano-Bonin operation. The target date was given tentatively as 15 April 1945.9
Admiral Nimitz, too, in planning for the projected Formosa invasion, pointed to the eventual Volcano-Bonin objective. In September 1944 he advised Lieutenant General Holland M. Smith, Commanding General, Fleet Marine Force, Pacific, that it was desirable to retain the 2d and 3d Marine Divisions in the Marianas as an area reserve for Formosa and
CHICHI JIMA had a good harbor but was too rugged to accommodate extensive airfields. (AF Photo)
as the major troop units for an impending attack on Iwo Jima.10
During September 1944, top Navy, Army, and Army Air Force commanders began to express doubt concerning the wisdom of an operation against Formosa. Early in the month Lieutenant General Millard F. Harmon, USA, Commanding General, Army Air Forces, Pacific Ocean Areas, advocated bypassing Formosa in favor of the Bonins and Ryukyus. Lieutenant General Robert C. Richardson, Jr., USA, Commanding General, Army Forces, Pacific Ocean Areas, saw "no advantage whatsoever in the capture of Formosa," and preferred striking through the Nanpo Shoto. Admiral Nimitz, in a communication to his top commanders, indicated that seizure of Formosa would only be in preparation for operations against the China coast. Recent Japanese military gains in that area caused Nimitz to question the value of such a move.11
Late in September Admiral Nimitz and Admiral Ernest J. King (Cominch and Navy member of the Joint Chiefs of Staff) met in San Francisco. Admiral Raymond A. Spruance (Commander, U.S. Fifth Fleet), who had been on leave in California, was ordered to attend this conference and his interesting account of that meeting and its preliminaries follows:
After the completion of the Marianas Operation I turned my command over to Admiral Halsey on 28 August 1944, and returned to Pearl Harbor early in September. On reporting to Admiral Nimitz, he advised me that my next operation would be the capture of Formosa and Amoy. I said that I though Iwo Jima, followed by Okinawa, would be preferable, but was told that the orders from CominCh called for Formosa. . . .
At this Conference [San Francisco] Admiral Nimitz presented a paper--prepared, I believe, by Captain Forrest Sherman, USN, head of Fleet War Plans Division--recommending the substitution of Iwo Jima and Okinawa for Formosa and Amoy. The reason for this change was that Lt. Gen. S.B. Buckner, USA, Commander 10th Army, who was to command the Landing Force for Formosa, said that he had insufficient Service Troops for an objective so large as Formosa; but that he could take Okinawa. Admiral King, after considerable discussion, was convinced of the necessity for the change and so recommended to the J.C.S., who approved it.12
Immediately following the conference (2 October 1944) Admiral King returned to Washington and submitted a proposed directive for future operations. He indicated that there were not sufficient ground forces available in the Pacific to meet the minimum requirements for an invasion of Formosa and the southeast China coast. Furthermore, the War Department had revealed that there could be no increase in these troops until cessation of the war in Europe. The proposal stated, however, that occupation of positions in the Nanpo Shoto, specifically Iwo Jima in January 1945, would allow fighter support for the B-29's operating from the Marianas. Also, a move into the Nansei Shoto, particularly Okinawa, would sever Japanese air communications throughout the
COMINCH WITH TWO OF HIS TOP ADMIRALS. From left to right: Admiral Spruance, in over-all command of Iwo operation; Admiral King, who advocated Iwo's capture to JCS; Admiral Nimitz, CinCPac-CinCPOA.
Ryukyus. Forces to accomplish these two operations were available.13
The Joint Chiefs of Staff accepted Admiral King's proposal almost immediately and issued a new directive on 3 October that guided the Pacific War to a conclusion. CinCPOA was directed to conduct the following operations:
- Provide fleet cover and support for the occupation of Luzon by Southwest Pacific Forces, target date 20 December 1944.
- Occupy one or more positions in the Nanpo Shoto, target date 20 January 1945, [Italics by author.]
- Occupy one or more positions in the Nansei Shoto, target date 1 March 1945.14
The same arguments that dictated the decision to take an objective in the Nanpo Shoto led inevitably to the final choice of the objective. Use of the airfields in the area must be denied to the Japanese and quickly gained for United States forces. Only Iwo Jima could satisfy this requirement and justify a military operation of the magnitude necessary to assure success.
A top secret dispatch from Admiral Nimitz on 9 October 1944 informed General Holland M. Smith that Iwo Jima was definitely the objective.15
The Joint War Plans Committee, in the outline of "Operations for the Defeat of Japan," dated 18 October 1944, placed in proper perspective the part Iwo played on the Pacific stage. Its seizure was listed as a contributory operation in keeping with the over-all objective of the war. In effect, this operation would contribute toward lowering Japanese ability and will to resist by: (1) establishing sea and air blockades; (2) conducting intensive air bombardment; and (3) destroying enemy air and naval strength. The capture of this island
would help make feasible ultimate invasion of the industrial centers of Japan.16
The decision to take Iwo Jima, like many strategic decisions, had been based on projected plans. Airfields in the Marianas, from which B-29's would operated against the Empire, were still under construction on 3 October when the Joint Chiefs issued their directive for the drive northward. But by D-Day, 19 February 1945,17 B-29 attacks against Japan from Marianas bases had been a reality for nearly three months. Plane and crew losses over Japan and on the long return trip bore tragic testimony to the need for an intermediate base from which fighters could provide protection over the target and where damaged bombers could find secure haven. Never before in the Pacific War had troops engaged in amphibious assault been able to see so clearly the immediate importance of the objective. Long before the battle ended, fighting Marines saw hugh crippled "Superforts" land safely on an airfield just recently cleared by costly, bitter fighting.
Planning for the Iwo Jima operation was affected by the Philippine operations which immediately preceded it. By mid-November it became evident that the 1-month interval between the Luzon operation (20 December) and the Iwo target date (20 January) would not allow sufficient time for reallocation of amphibious and support shipping from one operation to the other. For this reason Admiral Nimitz recommended that target dates for operations DETACHMENT (Iwo Jima) and ICEBERG (Okinawa) be deferred to 3 February and 15 March respectively.
Operations in the Philippines were unexpectedly prolonged. Attempting to hold Leyte at all costs, the Japanese had successfully reinforced their garrison by landing two divisions, one infantry regiment, and various supporting troops. In addition, rain and mud seriously impeded United States troop movement and construction of airfields.18 In the face of these delays General MacArthur was likewise caught in a time squeeze. Accordingly, the assault on Luzon was ordered postponed to 9 January 1945, again throwing Nimitz' Iwo and Okinawa plans out of kilter. Consequently, in early December JCS received from CinCPOA a recommendation that operations DETACHMENT and ICEBERG be further delayed to 19 February and 1 April 1944. respectively.19 The Joint Chiefs concurred and the target dates were readjusted accordingly.
Initial planning for Iwo could not anticipate these changes in target dates. Upon receipt of the JCS 3 October directive with a target date of 20 January listed for taking Nanpo Shoto positions, CinCPOA and his Joint Staff immediately went to work. The result was a Joint Staff study published 7 October 1944 and issued to major subordinate commanders for use in preliminary planning. The document was not considered a directive, however, and did not commit the Commander-in-Chief, U.S. Pacific Fleet and Pacific Ocean Areas to any specific course of action.20
Purposes of the DETACHMENT operation were clearly designated in this study:
To maintain unremitting military pressure against Japan.
To extend our control over the Western Pacific.
To establish a base from which we may:
- Attack the Japanese Empire.
- Protect our bases in the Marianas.
- Cover our naval forces and conduct search operations in the approaches to the Japanese Empire.
- Provide fighter escort for very long range operations.
Specific tasks envisioned were:
- To reduce Japanese naval and air strength and production facilities in the Empire.
- To destroy enemy naval and air strength in the Bonins.
- To capture, occupy and defend Iwo Jima and develop an air base on that island.21
LIEUTENANT GENERAL HOLLAND M. SMITH
commanded the Expeditionary Troops at Iwo Jima.
On 9 October General Smith received this staff study along with Admiral Nimitz' directive ordering the seizure of Iwo Jima. The directive named these commanders for the operation:
- Operation Commander
Admiral Raymond A. Spruance, USN.
- Joint Expeditionary Force Commander
Vice Admiral Richmond Kelly Turner, USN.
- Commanding General Expeditionary Troops
Lieutenant General Holland M. Smith, USMC.
- Second in Command Joint Expeditionary Force
Rear Admiral Harry W. Hill, USN.
General Smith started planning immediately in conjunction with the Commander Fifth Fleet; Commander Amphibious Forces, Pacific; Commander Service Force, Pacific; Commander Air Force, Pacific; Commanding General, Pacific Ocean Areas; and Commanding General, Army Air Forces, Pacific Ocean Areas.22
Within a few days General Smith issued a letter of instruction which designated Major General Harry Schmidt, Commanding General, V Amphibious Corps, as Commanding General of the Landing Force. General Schmidt and his experienced staff, headed by Brigadier General William W. Rogers, assumed responsibility for preparing and executing all Landing Force plans for the operation. The staff of Headquarters, Fleet Marine Force, Pacific, was at their disposal for any assistance they might require. Upon completion of Landing Force plans, General Schmidt was to submit them to General Smith for approval.23
Major units assigned to the Landing Force for planning, training, and operations were the 3d, 4th, and 5th Marine Divisions. Of these, the 3d and 4th Divisions, commanded by Major General Graves B. Erskine and Major General Clifton B. Cates, respectively, were veteran fighting units. Major General Keller E. Rockey's 5th Division, about to experience its first battle action as a unit, contained many seasoned and combatwise troops who had helped subdue other Pacific strongholds.
After participating in the highly successful Saipan and Tinian operations, the 4th Division had only recently returned to its camp site on Maui, T.H. The 5th Division had embarked from San Diego the previous August for a training area on the big island of Hawaii, T.H. With both of these major units in the Hawaiian area, close liaison could be affected between them and with various echelons at Pearl Harbor. The 3d Division, on the other hand, was encamped on Guam, having recently completed the liberation of that island. Similarly, General Schmidt had located his V Amphibious Corps command post on Guam.
To facilitate and speed planning for the Iwo operation, VAC Headquarters moved to Pearl Harbor on 13 October 1944. All major planning staffs, with the exception of the 3d
Division,24 were now in the Hawaiian Area, so that intimate coordination of effort could be effected. All subordinate commanders--assault, support, and garrison--reported to the Landing Force Commander at an early date, and joint planning soon began.
Not only were the individuals of the various staff well acquainted with their jobs; they were also, for the most part, well acquainted with one another. Previously the V Amphibious Corps had participated with the Fifth Fleet in operations for the capture of the Gilberts, Marshalls, and Marianas. With the proximity of these staff affording immediate exchange of information between all echelons of command, the work proceeded smoothly and efficiently and plans were issued almost simultaneously.
MAJOR GENERAL HARRY SCHMIDT commanded the V Amphibious Corps Landing Force at Iwo Jima. (From painting by Albert K. Murray, USNR)
The first tentative operation blueprint for the Landing Force was issued by General Schimdt on 19 October as a guide for subordinate commanders. One day later, CG, FMFPac issued a directive to CG, Landing Force in which troop assignments for training, planning, and operations were designated. Corps was directed to be ready for combat in all respects by 15 December.25
During the next two months General Schimdt's original plan went through many changes. The effect of increasingly complete intelligence was reflected in amendments to original concepts. Even the issuance of final operation plans did not prevent flexibility, and changes continued to be made up until D-Day.
In close sequence, final drafts for Operation DETACHMENT were published on the following dates:
25 November -- CinCPOA Operation Plan 11-44. 23 December -- VAC Operation Plan No. 3-44. 27 December -- Joint Expeditionary Force Operations Plan No. A25-44 31 December -- Fifth Fleet Operation Plan No. 13-44.
By 26 January 1945, when Admiral Spruance assumed command of all forces assigned to central Pacific Task Force for the Iwo operation, CinCPOA's Plan 11-44 was fully in effect.26
That the landings at Iwo would have to be made over the southeast beaches was a near certainty. Predominant northerly or northwesterly winds caused hazardous swells almost continuously on the southwest side of the island. Preferred plans were drawn accordingly. On 8 January 1945, however, VAC issued no alternate plan to cover the possibility of adverse surf conditions along the southeastern beaches. Except that it prescribed using beaches on the western side of Iwo, this alternate plan differed little from the preferred plan.
Designated for the beach assault were the 4th and 5th Divisions, less the 26th Marines, which was to remain in Landing Force reserve. For training purposes, however, the 26th Marines would remain with the 5th Division. After staging on Guam, the 3d Division was to be in Expeditionary Corps reserve and would be available afloat in the objective area on D-plus-3.
In anticipation of the possibility of a strong reaction by enemy planes, the 138th Antiaircraft Artillery Group (Army), commanded by Colonel Clarence E. Rothgeb, was attached to the assault force to land on order and provide antiaircraft protection for the beachhead and the airfields when secured.27
Commanders decided that corps artillery should be kept at a minimum, since there was limited space for emplacement on the island. It was reasoned that air and naval gunfire would compensate for this lack. Corps artillery was restricted, therefore, to two battalions of 155mm howitzers organized as the 1st Provisional Field Artillery Group, under Colonel John S. Letcher.
A reevaluation of enemy strength and misgivings as to the effectiveness of the short (3-day) period of naval gunfire preparation, coupled with the importance of rapid seizure of the commanding Mount Suribachi area by the 5th Marine Division, brought about an 11th-hour amendment to the assault task force organization. On 14 February General Schmidt released one battalion of the 26th Marines (1/26) to the 5th Division,28 and requested that one RCT of the 3d Marine Division be made available at Iwo on D-Day to replace RCT 26 as corps reserve. This would permit release of the 26th Marines to its parent organization (5th Marine Division) for use in the assault if necessary.29
The request was approved and TransDiv 32 (carrying the 21st Marines) ordered to leave Guam on 16 February to report to Admiral Turner at the objective at 1000 D-Day.30
The corps scheme of maneuver for landing was not complicated. The 4th and 5th Divisions would land abreast on the southeastern beaches with the 5th on the left. As Expeditionary Troops Reserve, the 3d Division, when released to corps would land over the same beaches on or after D-plus-1, prepared to assist in the attack or occupy defensive positions as ordered. Infantry RCT's31 and their assigned beaches were as follows:
Scheme of Maneuver
3D DIVISION (EXPEDITIONARY TROOPS RESERVE) 3d Marines (Division Reserve) To be ordered later as necessary 9th Marines YELLOW 1 and YELLOW 2 21st Marines RED 1 and RED 2 4TH DIVISION 23d Marines YELLOW 1 and YELLOW 2 24th Marines (Division Reserve) BLUE or YELLOW, as ordered 25th Marines BLUE 1 5TH DIVISION 27th Marines RED 1 and RED 2 28th Marines (less 3d Bn) GREEN 1 3d Bn, 28th Marines (Division Reserve) RED or GREEN 1st Bn, 26th Marines (Division Reserve) RED or GREEN 26th Marines (less 1st Bn) (Corps Reserve) As ordered
Colonel Harry B. Liversedge's 28th Marines would attack on the extreme left of the corps, cut straight across the narrow neck of Iwo, then turn southwest to secure the Mount Suribachi area. On the immediate right of the 28th Marines, Colonel Thomas A. Wornham's 27th would attack to the opposite shore, then turn
northeast and seize the O-132 line in its zone. The action of these two RCT's would clear the enemy from the dominating heights at the southern end of the island and secure the corps' left flank and rear. (See Map III.)
Map III: Landing Plan
The 4th Division would employ Colonel Walter W. Wensinger's 23d Marines first to seize Motoyama Airfield Number 1, then to turn northeast and clear that portion of Motoyama Airfield Number 2 and the O-1 line in its zone of action. Colonel John R. Lanigan's 25th Marines, on the corps' right flank, was to assist in the capture of Airfield Number 1 and seize Beach BLUE 2 and the O-1 line in its zone of action.33 These 4th Division objectives included the southern portion of Airfield Number 2 and the rugged southern edge of the Motoyama Plateau. It was foreseen that this cliff line dominating the BLUE Beaches must be captured as quickly as possible.
Commanding the 24th Marines, Colonel Walter I. Jordan would stand ready in 4th Division reserve to support the assault as ordered. Similarly, the 26th Marines, commanded by Colonel Chester B. Graham, was prepared to support the 5th Division after release from corps reserve on D-Day.
Division artillery would move into selected positions upon order from the respective division commanders; Colonel Louis G. DeHaven's 14th Marines in the 4th Division and Colonel James D. Waller's 13th Marines in the 5th Division.
At H-Hour 68 LVT(A)4's of the first wave would hit the beach and proceed inland to the first terrace or bluff beyond the high-water mark. Here they would deploy to bring their maximum fire power to bear, affording covering protection to the succeeding waves of infantry debarking from LVT's.
Initially the VAC operation plan prescribed tanks of the 4th and 5th Tank Battalions to land in a scheduled wave at H-plus-30 minutes. Later studies of the beach terrain and anticipation of congestion at the water's edge, however, convinced division planners that the tanks should be "on call." Regimental commanders would be permitted to use their discretion as to the appropriate times.34
As previously indicated, the alternate scheme of maneuver to employ the western beaches was little different from the preferred plan. It did, however, include an interesting addition, centered around Kangoku Rock, a 600-yard long bit of volcanic cast-off lying some 2,250 yards off the northwestern shores of Iwo. At H-minus-50 minutes a company of the 24th Marines, reinforced by a platoon of armored amphibians from the 2d Armored Amphibian Battalion, was to seize this spot as a possible artillery site. The 105mm howitzers of the 4th Battalion, 14th Marines were to be prepared to land on Kangoku Rock on order.
When the V Amphibious Corps began planning for the Iwo operation in October, a considerable amount of excellent intelligence information was already available. Documents captured on Saipan in June provided a fairly complete picture of the enemy forces and dispositions in the Volcano-Bonin area. Enemy maps, U.S. Hydrographic Office charts, and aerial photos taken in conjunction with carrier strikes in June and July35 were used to compile
situation maps and beach studies of remarkable accuracy. But information concerning the enemy order of battle was incomplete because it did not reflect changes that occurred subsequent to the fall of Saipan, and the hydrographic and terrain data, while good as far as it went, needed amplification.
The corps intelligence section was responsible for collection, evaluation, and dissemination of intelligence for all elements of the landing force. The G-2 section, FMFPac rendered valuable assistance in procuring maps, photographs, bulletins, and maintaining essential liaison between VAC and the Joint Intelligence Center, Pacific Ocean Areas (JICPOA). Intelligence officers from FMFPac formed the 2-section of the Expeditionary Troops (TF 56) staff for the operation but did not function in that capacity until embarkation for the rehearsals in December.36
Aerial photographs were a major source of information, and during the planning phase of the operation 371 photo sorties were flown. Navy Photographic Squadrons 4 and 5 and the 28th Photographic Reconnaissance Squadron of the Army Air Force contributed most of the coverage. This was augmented by strike photos taken by Seventh Air Force bombers during their bombardment missions. Ample periodic coverage permitted constant checking of the enemy's defense efforts.37
One of the highlights of preassault intelligence was the extent of cooperation in this effort. In October 1944 officers of Admiral Turner's staff coordinated information disseminated by Amphibious Forces, Pacific and Fleet Marine Force, Pacific. Direct liaison was maintained between photo interpretation units of both echelons. This resulted in the production of a Joint Situation Map on 6 December. The scope of these joint activities extended to all naval and Marine Units involved in the Iwo Jima operation.
Out of this consolidation of effort evolved a decision to publish a single Joint Enemy Installation Map to issue to all organizations making or supporting the assault. Late in January 1945, photo interpretation officers from each major participating unit assembled on Guam. These representatives from FMFPac, VAC, 3d, 4th, and 5th Marine Divisions, Joint Expeditionary Forces, and Amphibious Group Two, examined all photographs that accumulated in the forward area after 5 January and with the receipt of excellent pictures taken during the 2-10 February period they were ready to produce the final Enemy Installation Map.38
Previews of the target were not limited to aerial observation. Early in December 1944, a United States submarine, the Spearfish, snooped just off the coast of Iwo and through his periscope the sub commander watched the activities of enemy troops. His observations were recorded and given wide circulation along with periscope photos of beach areas. Most of this data provided valuable as substantiation of previous information.39
Beach studies indicated the movement over the loose sand would be difficult for wheeled vehicles but that tractors would find it somewhat easier. Partially buried gasoline drums were observed at the water's edge on both the east and west beaches. Their regular pattern led intelligence experts to believe that they might be some kind of beach obstacles. This belief was strengthened by capture of Japanese documents giving detailed instructions for employment of burning gasoline to check hostile landing forces.40
Analysis of the organization of ground forces on Iwo Jima indicated that the Japanese garrison was applying lessons learned from defensive failures on other islands. Their beach defenses appeared to be organized in depth with open areas covered by extensive antitank defenses and machine guns laid on final protective
B-24's HIT IWO and other islands in the Volcano-Bonins for 74 consecutive days
beginning 8 December 1944. (AF Photo)
lines. The light artillery of infantry units were learning how to fight without adhering to the rigid perimeter defense that had marked their earlier tactics.
Intelligence officers took particular note of the fact that field works seemed adequate for only four of the nine infantry battalions known to be on the island. This left five battalions in reserve, held out to execute a counterattack. But it was pointed out, the enemy might now see the folly of beating uselessly against our well established beachheads. Preassault studies indicated that if the enemy should fail in his first full-scale attack against our positions, he would in all probability fall back to high ground in the center of the island to hole up, and resist fanatically to the last man.
Although enemy antitank defenses and weapons had proved inadequate in the past, Marines were warned to expect extensive use of antitank mines and obstacles, combined with "close quarter attack units" using hand-placed charges. It was cautioned also that infiltration tactics designed to knock out tanks as well as command posts, communications, artillery, and mortars were likely.
No change was anticipated in the enemy's artillery tactics. Although many artillery pieces were reported on the island, there did not seem to be any indication that massed fires would be encountered in larger than battery concentrations. Reference was made to the fact that Japanese infantry had always been reluctant to forego close support in favor of general support.41
Study of aerial photographs and captured documents showed that Iwo was probably divided into four defense sectors with one infantry battalion manning the defenses in each sector. The principal concentration of entrenched forces provided maximum strength in the southern part of the island to defend the vulnerable east and west coasts. These positions consisted of pillboxes and fire trenches. Here lines of fortification were known to be strengthened by extensive employment of antitank and beach mines. Lack of noticeable activity in the north led intelligence officers to assume that enemy fortification in that locality held less attention, and for good reason. There nature allied herself with the Japanese. The steep cliffs would all but prohibit invasion over northern beaches. Even so, one battalion was reported to be in defensive position along this northern coastal area with its companies deployed along the rocky heights overlooking the ocean.
Aerial photos taken during early 1945 revealed that the number of field fortifications,
pillboxes, and covered artillery positions increased despite air bombardment. The most significant development noted in photographs was the construction of a defensive line traversing the island from coast to coast. These fortifications stretched from a point near Hiraiwa Bay on the northwest coast to high ground north of the East Boat Basin. This line appeared to be a chain-like series of centers of resistance and was obviously established in depth. A study of these changes resulted in a sharp upward revision in estimate of enemy strength on Iwo. Relative to this adjustment, intelligence authorities states that:
Photographic coverage of Iwo Jima to 24 January 1945, indicates that damage to installations resulting from bombing strikes between 3 December 1944, and 24 January 1945, was, on the whole, negligible. These strikes have apparently not prevented the enemy from improving his defensive position and, as of 24 January 1945, his installations of all categories had notably increased in number. The island is now far more heavily defended by gun positions and field fortifications than it was on 15 October 1944, when initial heavy bombing strikes were initiated.42
A comparative tabulation of enemy installations issued 13 February illustrated the progress of Japanese defensive preparations:
Gun positions Type To 3Dec44 To 10Feb45 Increase Percent Coast defense 3 6 100 Dual purpose 16 42 162 Dual purpose (empty) 4 8 100 Automatic AA 151 203 41 Automatic AA (empty) 2 16 700 Covered artillery 39 67 71 Open artillery 40 5 -87 Antitank-antiboat 18 3 -83 Machine guns 352 292 -17 Total 626 642
Commenting on the apparent decrease in number of some types of gun positions the G-2, Expeditionary Troops, stated:
. . . . the apparent reduction in observed MG's may be offset by the heavy increase in field fortifications, including blockhouses and pillboxes. The blockhouses may contain fixed artillery and, in many instances, their construction is such as to permit mobile artillery pieces to be wheeled into them. It is also considered that each pillbox provides emplacements for one or more heavy or light MG's. But even in the figures given above were to be accepted as showing no important change in totals, they do reveal significant increases in the number of heavy caliber weapons: CD's, DI's, and Auto. AA's.43
Intelligence officers estimated that Iwo's defenders numbered between 13,000 and 14,000 troops. In the C-2 Study of Enemy Situation, issued 6 January 1945, the Japanese order of battle is given as follows:44
2d Mixed Brig: Hq and 6 IndInfBn's 3,700 Arty Bn 400 Engr Bn 500 Fld Hosp 120 Total Brig 4,720 145th Inf Regt: Hq and 3 InfBn's 3,475 Sig Co 150 Regt Gun Co 150 AT Gun Co 125 Total regt (estimated) 3,900-4,000 2 AT Gun Bn's 1,000 Mortar Bn 600-700 Detachment, 26th Tk Regt 350 Br, 59th Anchorage 25 Army Fort Section 20 Iwo Jima Naval Guard Force 1,500-2,000 Naval Airbase Personnel 400 Construction Personnel 700 Total Army 10,600-10,800 Total Navy 1,900-2,400 Total construction 700 Total Iwo Jima 13,200-13,900
It was known that the backbone of this force was the 2d Mixed Brigade of the 109th Division, believed to bed commanded by Major General Koto Osuka, and Colonel Masuao Ikeda's 145th Infantry Regiment. A detachment of the 26th Tank Regiment with about 30 medium and ten light tanks were reported on Iwo, but the whereabouts of Colonel Takeichi Nishi, the regimental commander, and the bulk of his troops was uncertain.
Order of battle experts assumed that Lieutenant General Tadamichi Kuribayashi exercised
over-all command of the Volcano-Bonin Defense Sector from his 109th Division Headquarters on Chichi Jima, and that Major General Osuka was in charge of Iwo's defenses.
Information on the Japanese naval guard and air base units on Iwo was noticeably lacking in preassault intelligence. It was pointed out, however, that as a rule naval guard units such as the one thought to be on Iwo were usually commanded by a commander or a captain.45
Early in January, after careful study and evaluation of all enemy information, the Corps C-2 issued a statement of enemy capabilities:
- To defend initially by a combination of an active and passive defense with the mission of repelling or destroying our forces in the water and on the beach.
- To counterattack our beachhead with all available reserve strength under the cover of darkness.
- To reinforce and improve his defensive positions prior to D-Day.
- To attack our assault shipping with submarines, suicide-plane squadrons, and other special attack units--with carriers and transports as priority.
- To withdraw or abandon Iwo Jima.46
In modification of (e) above, C-2 believed that the enemy should not be expected to abandon Iwo without a fight. Being only three air hours from the homeland, Iwo was considered a keystone in Japan's inner defense system.
A D-minus-2 reconnaissance by underwater demolition teams (UDT's) would provide naval and troop commanders with up-to-date information on beach conditions. For liaison, specially trained Marines from the reconnaissance companies of the two assault divisions were attached to these units to make the trip to the beach. After the reconnaissance these liaison personnel would transfer at sea to the headquarters of their respective commands and furnish beach information to supplement official reports of the UDT Commander.47
In spite of efforts to maintain secrecy concerning the objective, some breaches of security did occur. For example, on 22 December 1944 the Honolulu Advertiser printed two excellent "Bombs Away" pictures with captions identifying the island target as Iwo Jima. The similarity between these pictures and the map of "Island X," which had been issued by VAC for training, was obvious.48
To offset possible serious consequences of such breaches of security, VAC ordered counterintelligence measures taken. Prior to leaving Hawaii, C-2 permitted information to leak out that all the buildup and activity was in preparation for an attack on Formosa in the near future.49
While the ships of Task Force 51 assembled in the Marianas and at Ulithi, Japanese submarines kept Imperial Headquarters in Tokyo fully informed of their movements. Thus, the enemy was well aware of the impending attack. Ten days before the assault, Tokyo advised the Volcano-Bonin command that an American attack would be launched soon, but the Imperial Chiefs could only guess as to whether the target would be Iwo Jima or Okinawa.50 The Formosa ruse does not appear to have affected Japanese estimates of United States intentions.
Although the Japanese intelligence experts in Tokyo were not able to predict exactly where the huge United States task force would strike, there seems to have been little doubt on Iwo. In fact, that garrison had a pretty good idea of when the attack would come and what units would make the assault.51
The major responsibility for logistical planning fell to the VAC staff. Even before the
Logistics and Administration
arrival of V Corps staff planners in Pearl Harbor on 13 October, however, such planning was underway.
The special staffs of FMFPac conducted preliminary conferences and drew tentative plans for logistical operations essential to the Iwo assault. Also, prior to General Schmidt's arrival in the Hawaiian area, the FMFPac staff handled all lower echelon correspondence and information requests regarding Iwo and logistics. The harmonious interworking at all levels of command paid real dividends. Within a short time, logistical planners issued directives that detailed exactly who would do what, where, when, and how.
The Quartermaster, U.S. Army Forces, Pacific Ocean Areas, would supply rations for all participating troops; also all clothing, special equipment, supplies, and ammunition for Army troops at Iwo. The Navy's Service Force, Pacific, would provide the necessary fuels and lubricants. Ammunition, special supplies, and equipment for the Marine troops were to be provided by the Supply Service FMFPac.52 These latter supplies were to be distributed initially by the 6th Base Depot through the 1st and 2d Service and Supply Battalions in Hawaii, and by the 5th Field Depot through the 3d Service Battalion on Guam.
Tending to complicate the supply problem was the 3d Marine Division's role as Expeditionary Troops reserve. To predetermine the amount of combat participation of this division and the time of its battle commitment was, of course, impossible. For this reason supplies earmarked for the 3d were loaded separately, so that, if the division were not used on Iwo, these materials would be available for future operations.
Stocks of ready packaged supplies were to be maintained at the 7th Field Depot on Saipan by the Air Delivery Section, VAC, for emergency delivery by air. The Expeditionary Troops Commander was also at liberty to draw from other stockpiles in the Marianas and Hawaiians.
Prior to the establishment of supply dumps ashore, vital materials were to be furnished from preloaded LST's. Using the shore party communication channels, requests for such supplies would be transmitted to logistical personnel on control vessels. They, in turn, would dispatch LVT's, DUKW's, or other craft to the LST's to pick up the desired items and deliver them to the beach.
The 8th Field Depot was organized by VAC for the Iwo operation and as such was to be the nucleus of the shore party organization. Commanding this depot was Colonel Leland S. Swindler, also designated as the Landing Force Shore Part Commander. His responsibility on the beach was to coordinate the activities of the division shore parties.
Absence of reefs off the shores of Iwo Jima offered obvious advantages to the ship-to-shore movement. All types of landing craft would be able to make the run from the transport area to the beach without the time-consuming reef transfer operations that had marked previous Central Pacific landings. Because of this, V Corps units were authorized to palletize53 supplies up to 50 percent when practicable.
It was foreseen, however, that the soft sand along the beaches, plus the steep gradient and high inshore banks, would render all movement of wheeled vehicles difficult. As a partial solution, runner sleds were supplied that could be loaded with necessary items and hauled across the beaches to inland points by tracked vehicles.
Marston matting, it was determined, would also be invaluable on Iwo's beaches. Designed originally for use in making airstrips, this material had been found ideally suited for use by assault troops in construction of temporary roadways over soft, yielding beach terrain. It came in plank-shaped lengths, ten feet long and 14 inches wide, each weighing 65 pounds. The shore party developed a means of hinging these lengths into 50-foot "accordion-pleated" units. Seven of them were bound together and lashed on sleds to be towed by tracked vehicles. As
it was pulled along, the matting would unfold neatly and quickly over the sand. Altogether, 8½ miles of this hinged matting was prepared at the Pearl Harbor Navy Yard for the operation.
In earlier operations the Sherman M4A2 (medium) tanks had been landed from landing craft, mechanized (LCM's) or landing craft, tank (LCT's). When the M4A2's were replaced by the newer, heavier M4A3 tanks for this campaign, tests revealed that LCM's carrying them rode dangerously low at the bow. As a result, landing ships, medium (LSM's) were used in lieu of the LCM's.54 For the Iwo operation all tanks went ashore in LSM's except those of Company A, 5th Tank Battalion, which were carried from a landing ship, dock (LSD) to the beach in three tank landing craft (LCT's).
Among the great variety of amphibious equipment available for landings, two items were new to the VAC: the Clever-Brooks 3½-ton amphibian trailer, and the light cargo carrier M-29C (weasel), capable of hauling a half-ton load. The amphibian trailers, two-wheeled towed vehicles, reached the 3d Division in November 1944, while the 4th and 5th Divisions received their allotments later in December. Training exercises revealed these trailers to be difficult to handle but, nevertheless, they were utilized as "one-way" carriers to lift high priority preloaded cargo.
The weasels were received and distributed to the three divisions in November. Outstanding performance in tests and training exercises disclosed that these boatlike tracked vehicles resembling miniature LVT's without ramps, were valuable equipment. Critical shortages of repair parts, however, caused doubts as to the advisability of embarking the vehicles for Iwo. An air shipment of urgently needed parts erased these doubts, and all divisions loaded weasels. Additional parts were received by surface shipment in time to be distributed before the divisions sailed.55
Five amphibian truck (DUKW) companies were assigned to VAC units for the operation. Of these, three were Army and the 4th and 5th Marine Divisions had one each, known as Provisional Amphibian Truck Companies, FMFPac. During training, Army personnel who had many months of experience with the vehicles, rendered valuable assistance to the Marines. Spare parts again became a problem: 200 propeller shafts and 100 propellers were needed, and neither Army nor Marine procurement agencies could obtain them. To meet this emergency, the Pearl Harbor Navy Yard manufactured these items, but delivery was not made until 23 January 1945.
For engineer support, the divisions had their organic engineer battalions plus the 133d and 31st Naval Construction Battalions ("Seabees"), attached to the 4th and 5th Divisions respectively. In addition, the following units were assigned to VAC and placed under the Corps Engineer for operational control:
2d Separate Engineer Battalion (Marine).
2d Separate Topographic Company (Marine).
2d Bomb Disposal Company (Marine).
156th Ordnance Bomb Disposal Squad (Army).
62d Naval Construction Battalion (Navy).56
Engineer missions would include clearing of mine fields, bomb disposal, road building and maintenance, water supply, and early repair and improvement of airfields. One of the most common of all combat engineering missions--bridge building--was not assigned. Only minor culvert installation would be needed.
The 62d Naval Construction Battalion received orders to commence repairs and improvements on Airfield Number 1 as early as possible after the beach assault. The specific mission of this unit was to prepare air strips for OY-1's
(light observation planes) and fighter aircraft. Similarly, the 31st Seabees would repair and extend Airfield Number 2 to 7,000 feet for accommodation of B-29's. Target dates for completing these assignments were D-plus-7 and D-plus-10.57
With three divisions, plus corps troops and other supporting units committed in a heavily fortified area of less than eight square miles, high casualties were expected.58 The 3d, 4th and 5th Medical Battalions were integral parts of the divisions. Corps had its organic medical battalion, Evacuation Hospital Number 1, and the 38th Field Hospital. The latter, an Army unit, originally was slated to participate only as a part of the Garrison Force. Mounting concern regarding casualties, however, caused assignment of this hospital to the Landing Force.
After the Marianas operation, the Marine medical battalions were each authorized a 100-percent increase in patient facilities and equipment, from 72 to 144 beds. The three divisions of VAC thus could accommodate 432 casualties. Corps with the attached Army hospital, could care for 3,160. The 8th Field Depot carried cots, tents, blankets, and mess gear for an additional 1,500.59
Two hospital ships, the Samaritan and the Solace, and one APH (Auxiliary Personnel, Hospital), the Pinkney,60 were originally assigned for the operation, as was the LSV (Landing Ship, Vehicle) Ozark,61 which would serve as an auxiliary hospital ship. One other hospital ship, the Bountiful, was later scheduled for Iwo.
In addition, four hospital LST's [LST(H)] were to be stationed 2,000 yards off the beaches to serve as evacuation control centers. This was planned as the first step in the process of evacuation from the beach. There casualties would be logged, given additional emergency treatment, then transferred to other ships for further care. LCVP's would be available as ambulance boats to carry patients to the transports (which provided limited hospital facilities) and hospital ships. Casualties were to be taken to Saipan and Guam, where a total of 5,000 beds were available. Air transportation was scheduled as soon as air strips were ready to accommodate transport planes.62
In early Pacific operations whole blood for transfusions in a combat area had been obtained from on-the-spot personnel. However, with the establishment of a whole-blood distribution center on Guam it was now possible to provide for a vitally important mobile blood bank at the target area. Early in January a mobile blood bank facility, consisting of one medical officer and two corpsmen, was attached to the corps medical battalion. Operating on an evacuation control LST, this bank was to act as a local blood distribution center for ships receiving casualties and for medical units ashore. When the situation ashore permitted, this bank, complete with refrigerating equipment, would move in and function until regular air delivery of whole blood from Guam63 could be established.
Paralleling the problem of care and evacuation was the accurate reporting of casualties.
In some past operations many wounded were long carried as missing in action because their whereabouts remained unknown for several months. VAC took steps to prevent this situation at Iwo. The four LST(H)'s, as the first link in the chain of shore-to-ship evacuation, were to maintain complete records of receipt and disposition of casualties. Troop commanders on each transport were to assign a clerical NCO to record and report all casualties brought on board. All ships were requested to submit reports of casualties to corps headquarters; air evacuees were to be reported by the air evacuation officer. A casualty section of one officer and two NCO's was provided at corps to process these reports. Detailed plans were issued concerning the collection and internment of friendly dead, burial of enemy dead, establishment of cemetery sites, and graves registration.64
During the closing months of 1944, six replacement drafts embarked from the United States destined for duty with VAC. Each consisted of approximately 1,250 officers and men. Two of these contingents went to each of the three divisions, where some of the personnel were absorbed prior to departing staging areas for Iwo. For the most part, however, these units were kept intact for use with shore parties for employment on the beaches until needed to replace combat losses.65
Painstakingly, corps G-4 and G-1 sections worked out the many other details of logistical and administrative planning. As the target date for Iwo drew near, these plans meshed smoothly with the over-all operational scheme.
For troops in the Pacific during the war years, life boiled down to a very simple formula: training for combat, combat, more training, followed by more combat. At the lower echelons, where the intensive troop training programs were conducted, knowledge of the identity of the next objective was not necessary: sufficient the certainty that "another rock" had to be taken.
Training and Rehearsal
It was at the higher levels that the training program dealt with preparation for specific targets. The Commanding General, Fleet Marine Force, Pacific, assumed responsibility for training and equipping all forces under his command. A primary function of FMFPac in connection with this duty was the distribution to all subordinate commands of information concerning new developments and changes in amphibious techniques.
Following his assignment as Commanding General, VAC Landing Force, Major General Harry Schmidt assumed direct responsibility for the preparation and training of all units assigned to him for the operation. In addition to the routine training program, units of V Corps participated in tests and demonstrations of new types of amphibious vessels, craft, vehicles, weapons, and techniques developed in anticipation of revised enemy defensive doctrines.66
As the nature of the Iwo Operation became better known, the division training programs placed added emphasis on attacking fortified positions, reduction of pillboxes, detection, marking, and removal of mine fields, and the use and coordination of supporting arms.
During the period 15 to 30 November, the 4th Division conducted amphibious exercises in the Maalea Bay area of Maui, followed by a division field exercise based on the scheme of maneuver for the Iwo Jima operation. Two command post exercises were later held in the camp area.67
The 5th Division began specialized instruction and exercises as soon as initial plans for the operation were distributed. Special emphasis placed on the mission of the 28th Marines resulted in an effort to utilize terrain similar to southern Iwo Jima. Each battalion of that regiment received the benefit of exercises that involved landing on beaches thought to resemble Iwo's, and enveloping a hill mass remarkably like Mount Suribachi. In an area marked off to represent the objective, elements of the division actually executed the scheme of maneuver. This unit held three command post exercises
in the Hawaiian area, including one problem employing coordination of air, naval gunfire, and artillery support.68
Preparation of the 3d Division for the operation followed a pattern dictated by its assigned mission. Training exercises emphasized the various phases a reserve unit passed through while landing and moving up to the assault. Particular attention was paid to methods used in executing a passage of lines in order to continue the attack. Because this division would not land in the assault, no assault landing rehearsals were held. The plan called for 3d Division use of shore party facilities of previously landed organizations. Nevertheless, the division and combat team shore parties engaged in training exercises on Guam prior to embarkation.69
Replacement drafts did not reach the divisions until late in November. Although these men had undergone basic infantry training before leaving the United States, there was still much preparation to be accomplished in the short period of time remaining. Exercises were sorely needed to integrate these troops with the units to which assigned as combat replacements. It was necessary further to acquaint them with the shore party duties they were to perform prior to their commitment as infantrymen.
Training of the newly activated amphibian truck companies was delayed by the late delivery of the DUKW's. Tank-infantry maneuvers were handicapped by the necessity of considerable retraining of tank crews and maintenance personnel in operation of the new M4A3 tank.
The loading of assault elements staged in the Hawaiian Islands began on 24 December, following completion of amphibious training exercises. By 9 January, embarkation of all troops was concluded in preparation for initial rehearsals. As individual units completed loading, transport divisions carried them independently to Oahu where they assembled with other elements of the Joint Expeditionary Force.70
Dress rehearsals, conducted in the Hawaiian area from 12 to 18 January, involved major elements of the Landing Force scheduled for the assault. These mass exercises, based on the actual scheme of maneuver, took place at Maalea Bay, Maui, and Kahoolawe Island. During the entire time, emphasis was placed on communications and control.71
The absence of several assault organizations from Hawaiian rehearsals detracted somewhat from the over-all value of these exercises. Only two of the five LVT battalions assigned to the Iwo operation participated. The other three, which staged in the Marianas, sent liaison officers to observe the exercises and carry back information relative to changes in plans and procedures.72 During landing exercises, training tractors and landing craft replaced the missing units and provided Marines with the necessary practice in loading and landing. Another unit, the 4th Tank Battalion, was not present at rehearsal because of the delayed loading of LSM's.
Participation of V Corps Artillery was limited to part of group headquarters, the 2d 155mm Howitzer Battalion, and half of the 473d Amphibian Truck Company, USA. The only operations performed by the group involved testing primary radio circuits; the corps landed no equipment. No DUKW's were launched because of need to prevent corrosion and deterioration of preloaded ammunition, and LST's were not beached because of reefs off rehearsal landing beaches.73
In spite of these deficiencies, participating units felt that rehearsals were of definite value, especially to the 5th Division, then operating
for the first time as part of a corps. Experience gained while working with adjacent units proved valuable as weak links in control and communications came to light for subsequent correction.74
Final Rehearsals in the Marianas during the second week of February included ships and aircraft of the Amphibious Support Force (TF 52) and the Naval Gunfire and Covering Force (TF 54), neither of which had engaged in the Hawaiian maneuvers. All assault shipping was now assembled at Saipan, including all LVT's embarked in LST's of the tractor groups. Troops of assault battalions were transferred from APA's to LST's just prior to rehearsals. These exercises were held primarily to test coordination between supporting arms and the Attack Force, with the emphasis again centered on communications and control. Marines were boated but did not land. Shore fire control parties did land on Tinian, however, and conducted drills and tests of communications in connection with simulated bombardment. During landing exercises troops executed a ship-to-shore feint in LVT's as assigned for D-Day.75
By late 1944 American shipyards, operating on record-breaking production schedules, began to catch up with almost overwhelming shipping demands in the Pacific. Newly constructed ships made possible a reorganization in the composition of transport divisions for the Iwo operation. Now each division contained five APA's (auxiliary personnel, attack; i.e., troop transports) and two AKA's (auxiliary cargo, attack). Of these seven transports, one APA and one AKA carried troops and cargo from corps rather than division. Thus, each assault regiment had at its disposal for transportation four APA's and one AKA from a transport division. Three of these transdivs constituted a transport squadron capable of lifting a reinforced Marine division. Men and supplies of service elements were distributed among the ships of the transrons and the LST's and LSM's assigned to carry assault infantry (and their LVT's), artillery (in DUKW's), tanks, and other mechanized equipment. The organization of transports for Iwo resulted in a minimum separation of units from their equipment when loading.76
The 4th Marine Division loaded for combat at Maui between 27 December and 8 January, the 5th Division at Hawaii between 25 December and 16 January, and elements of the 3d Division later at Guam. Although not destined for the assault, the 3d Division arrived off Iwo combat loaded. The wisdom of this later became evident when the 21st Marines received orders to disembark for combat before other units of the division. This regiment arrived prepared for battle, with its equipment and supplies readily available when needed. Corps and garrison troops loaded in the Hawaiian area at various times between 23 December and 25 January with six APA's and four AKA's employed for these elements.77
Of the 63 LST's and 31 LSM's assigned to the operation, the assault divisions necessarily drew the lion's share. Each of these units used 19 LST's while the 3d Division managed with two to lift machines of the 3d Tank Battalion. The remaining tank landing ships lifted supporting elements of V Cops. Allotment of LSM's gave 16 to the 4th Division and 12 to 5th Division, while the others became part of V Corps shipping. One LSD assigned to the 5th Division to carry tank landing craft balanced the disproportionate allotment of LSM's.78
In anticipation of early need, V Corps preloaded (in addition to the primary cargo) infantry LST's with vital initial landing supplies. These included such items as water,
AIRFIELD NUMBER 2 and Japanese antiaircraft installations take 500-pound bombs from Seventh Air Force Liberators. Unfinished Airfield Number 3 is left center in picture. (AF Photo)
approximately two infantry battalion units of fire, 2,000 C and K rations, 1,200 D-rations, concertina wire, gasoline, and lubricants.79
The primary purpose of preloading was to assure a balanced supply of rations, fuels and ammunition for assault troops on D-Day. Such provision and replenishment allowed Marines to continue the attack while the bulk of supplies filtered ashore through the hands of the shore parties. A total of 28 LST's arrived at Iwo thus preloaded or understowed.80 In addition, 42 amphibian trucks (DUKW's) were preloaded at Pearl Harbor for early discharge on the beaches at Iwo. On the occasion of their introduction to V Corps operations, 50 of the new 3½-ton amphibian cargo trailers were preloaded at Guam with rations, fuels, and ammunition. These loads, embarked in the LSV Ozark, would supply troops ashore on D-Day, and the Ozark, following discharge of her cargo, would serve as an evacuation hospital.81
The fleet that lifted the Landing Force included a variety of vessels carrying a great diversity of items essential to waging modern war. These ships sailed from many different ports but all gravitated toward a common goal: Iwo Jima. Assault shipping transported over one ton of supplies for every man in the assault force, amounting to approximately 98,000 tons.82 A total of 485 ships of various types were employed by Task Force 51 during the operation. This includes combat vessels, assault shipping, and early Garrison Force echelons, but not vessels from other forces that operated temporarily under the senior officer present afloat at the objective.83
Upon completion of final rehearsals, the Landing Force convoy anchored off Saipan on 14 and 15 February. By late afternoon of the latter date all elements of the creeping tractor groups had pointed clumsy bows northward toward the volcano Islands. Slowly but surely they began to put distance between themselves and the Southern Marianas. The next day Transport Squadrons 15 and 16, lifting other elements of Major General Harry Schmidt's Landing Force, also weighed anchor and steered a northerly course toward Iwo. While en route to the objective, this assault force received cover and protection from a carrier unit and naval surface elements.84
Movement to the Objective
Most of the Landing Force units that staged on Guam were not scheduled to arrive at the target on D-Day. Therefore, these troops sailed after the assault divisions left Saipan. Supporting units of the 3d Division and corps troops sailed in LST's on the 16th, followed by the main body of the division in the faster transports the next day. These ships from Transport Squadron 11, less TransDiv 32, would stand by approximately 80 miles off the southeast coast of Iwo Jima, with the 3d and 9th Marines in Expeditionary Troops reserve.85 RCT 21 followed other plans. Leaving the 3d Division at Guam, it embarked in TransDiv 32 and departed a day earlier to arrive at the objective by 1000 on D-Day.
Before Marines set foot on Iwo Jima, that island had endured the longest and most intensive preparation given any objective in the Pacific during World War II. From the initial carrier raid of June 1944 to the pre-H-Hour bombardment on 19 February 1945, tons of explosives showered down on this small island until it seemed that means and will to resist must surely be smothered.
Air ActivitiesRegularly scheduled air strikes against the target began as early as August 1944. Air operations were divided roughly into two phases: those prior to 16 February (the strategic phase), and those conducted from then to D-Day. During this time the tempo of air raids increased steadily to the point where Marianas-based bombers hit Iwo with a daylight attack once every 24 hours. These strikes were accompanied by night harassing missions, fighter sweeps and photo reconnaissance flights.86
The workhorses of these air assaults proved to be the heavy bombers (B-24's) of the Seventh Air Force stationed in the Marianas. This campaign marked the greatest effort made by Seventh Air Force bombers in the Pacific. Commencing on 8 December, and continuing for 74 consecutive days, explosives from these aircraft rained on islands in the Volcano-Bonins, with particular attention given to Iwo Jima.87
Marine PBJ's (B-25 medium bombers) from VMB-612 participated in this bombing from early December 1944 until D-minus-20. These flying Marines operated from the Marianas under the VII Bomber Command and flew night sorties through the Volcano-Bonin Islands in an effort to disrupt enemy shipping activities. Because of omnipresent United States aircraft in this area during daylight hours the enemy made frantic attempts to supply their island outposts at night. Against this nocturnal logistics program Marines, using rockets and radar, operated with considerable success, reporting 23 Japanese ships sunk.88
All air missions on or after D-minus-20 were executed in compliance with provisions of the Iwo Jima Air Support Plan.89 During this period Marianas-based Liberators flew 30 to 34 sorties a day against the Iwo defenses.90 Although land-based aircraft missions over Iwo were controlled by Commander Task Force 93
(Lieutenant General Millard F. Harmon, USA), after D-minus-20 they were conducted according to requests of Commander Joint Expeditionary Force. Bombing missions were planned to accomplish the following:
- Neutralization of the airfields and installations on Iwo Jima.
- Destruction of gun positions and fixed defenses.
- Unmasking of additional targets.91
Naval ActivitiesThe initial plan for preliminary naval gunfire bombardment provided for one cruiser division to shell Iwo beginning on D-minus-8, to be joined on D-minus-3 by seven old battleships (pre-World War II) and six more cruisers.92
Planning for naval preliminary fires at Iwo was marked by three unsuccessful attempts by Marine naval gunfire specialists to lengthen the period of shore bombardment. Efforts to gain more time for preassault destruction of enemy defenses were based upon previous experience of Marines at Tarawa, Saipan, and Peleliu. In these operations prelanding naval activities left much to be desired, and the corps wanted to ensure more adequate softening of the target at Iwo. Requests for more than three days of fires were made in consideration of the known nature and number of defenses at the objective. The naval gunfire offices of V Corps believed that only a long period of deliberate destructive fire could properly prepare the target.
The first Marine request called for a 10-day bombardment by one cruiser division and three battleships. This proposal was turned down by naval commanders, and General Schmidt then asked for nine days. After failing a second time, the VAC commander made sweeping concessions and submitted a third letter requesting only four days of preliminary bombardment. But naval planners still insisted that their schedule would provide adequate preparation without even one more day.
In his fourth and final effort, General Schmidt asked for additional firing time. Realizing, however, that the Navy would probably continue firm in its decision to devote only three days to the task, he proposed as an alternative that shelling on those days be concentrated on and adjacent to the preferred landing beaches. This request received the same strong support from General Smith as all former attempts, but Admirals Turner and Spruance again held to the original plan.93
The Navy's major considerations in turning down Marine requests may be summarized as follows:
- The initial surface bombardment must be simultaneous with the first carrier attack upon the Tokyo area by the Fast Carrier Force (TF 58). The carrier attacks were to continue for three days but unforeseen conditions might force TF 58 to withdraw earlier. Therefore, if preparation fires at Iwo commenced on D-minus-4 and the carriers were forced to abandon their operations against the Empire in two days or less, the enemy would have sufficient time to recover and launch air attacks against United States invasion shipping off Iwo Jima.
- The limitations on the availability of ships, difficulty in replenishing ammunition, and loss of surprise interposed serious obstacles to a protracted preparation.
- The Navy plan for three days of firing would accomplish all the desired objectives.
- The prolonged air bombardment might be considered at least as effective as one day of additional surface bombardment.94
TOP COMMANDERS AT IWO. From left to right: Vice Admiral Turner, Expeditionary Force Commander; Major General Schmidt, Landing Force Commander, Lieutenant General Smith, Expeditionary Troops Commander.
The Amphibious Support Force of Rear Admiral William H.P. Blandy (TF 52), first of the American Forces to arrive at the target, experienced serious setbacks and revisions during preparations. Task Force 52 was composed as follows:
Gunfire and Covering Force (TF 54), RAdm Bertram J. Rodgers, USN.95
Support Carrier Group (TG 52.2), RAdm Calvin T. Durgin, USN.
Mine Group (TG 52.3), RAdm Alexander Sharp, USN.
Underwater Demolition Group (TG 52.4), Capt B. Hall Hanlon, USN.
Gunboat Support Units One and Two (TU's 52.5.1 and 52.5.2), Capt Theodore C. Aylward, USN.
Air Support Control Unit (TU 52.10), Capt Elton C. Parker, USN.96
Late in January it became evident that certain major support vessels would not be ready in time to take part in the preparatory bombardment as planned. These ships still supported General MacArthur's forces in the Philippines and could not be released while needed there. Others, damaged in recent operations, could not be repaired in time. Extensive changes in the gunfire support plan became necessary, and Navy commanders began scouring the Pacific ocean areas for replacement battleships and cruisers for Iwo. New schedules of ships' bombardment duties, based on a revised naval task organization, were ready by 28 January97 and included the battleships North Carolina and Washington (BB's--new battleships). Admiral Spruance now indicated that
these two heavy bombardment vessels with their powerful 16-inch guns would not arrive off the target until D-Day. A second revision of gunfire support plans now became necessary, and firing schedules and sector assignments were again altered.98
Other naval commands were also active toward the end of January in preparing to support the coming operation. At midnight, 26 January, Admiral Spruance relieved Admiral William F. Halsey at Ulithi, and the U.S. Third Fleet thereby became the Fifth Fleet. Concurrently, command of the Fast Carrier Force passed from Vice Admiral John S. McCain to Vice Admiral Marc A. Mitscher, and it became Task Force 58, soon to strike the Empire in support of the Marine attack in the Volcanos.99
Task Forces 52 and 54 arrived in the Marianas from Ulithi on 12 February and engaged in final rehearsals with the invasion fleet. Shore bombardment units left the Saipan-Tinian area on 14 February and arrived at the objective early in the morning of 16 February.100
The decision to limit pre-D-Day preparation fires to 3 days (16-18 February) imposed a tremendous task on the heavy support ships of Rear Admiral Bertram J. Rodgers' Naval Gunfire and Covering Force (TF 54). The mission of these vessels was to knock out or neutralize the most powerful and threatening enemy defense installations prior to D-Day. Target priorities for the preliminary bombardment were as follows:
Priority A--Installations that threatened ships, aircraft, and UDT operations (coast defense and antiaircraft guns, artillery emplacements, antitank guns).
Priority B--Installations threatening the Landing Force in the ship to shore movement (blockhouses, covered artillery, pillboxes, machine guns, command posts).
Priority C--Installations such as caves, ammunition and fuel dumps, bivouac areas.
Shore bombardment ships assumed the responsibility for dealing with a total of 724 A and B priority targets. And the job would have to be accomplished by six old battleships, four heavy cruisers and one light cruiser.101
Admiral Blandy and a large staff on board the Estes (AGC 12), controlled all activities at the target during the preassault period. Assisting the Amphibious Support Force commander at this time were Lieutenant Colonel Donald M. Weller, USMC, V Corps Naval Gunfire Officer; and Captain Elton C. Parker, USN, commanding the Air Support Control Unit of TF 52.102
Upon arrival at the objective, heavy support units came under direction of Admiral Blandy for shore bombardment. Firing commenced at 0800, with support vessels following mine sweepers that swept shoreward from the 100-fathom mark. Initial ranges for gunfire were therefore, great, making airborne spotters and observers indispensable. All fire support units received orders to shell Iwo only when specific targets could be identified and impacts observed from the air.103
Map 2: Naval Gunfire Areas of Responsibility, D-3 and D-2
Observers and spotters found their task almost impossible because of a low ceiling that caused poor visibility. Planned firing schedules could not be carried out, and each ship fired in its assigned sector whenever the weather permitted.104 During rare moments when Iwo became visible from the air, intensive antiaircraft fire forced United States observation planes to remain at altitudes above 3,000 feet, preventing accurate assessment of gunfire effects. At the end of firing on 16 February, damage to enemy installations appeared negligible.105
In spite of the unfavorable weather on D-minus-3, air operations continued, and a total of 158 sorties were flown that at least kept the enemy off balance. Airfield Number 1 was strafed and hit with rockets by eight Navy fighters. During periodic clearing of the skies carrier aircraft also managed to attack gun emplacements on Mount Suribachi. In the afternoon Army Air Force bombers arrived over Iwo but could not complete successful bomb runs because of the dense overcast.106
The bulk of the missions flown on 16 February were by Navy flyers from Rear Admiral Calvin T. Durgin's Support Carrier Group (TG 52.2). This included the escort carriers (CVE) Sargent Bay, Natoma Bay, Wake Island, Petrof Bay, Steamer Bay, Makin Island, Lunga Point, Anzio, Bismarck Sea, Saginaw Bay, Rudyerd Bay. Until land-based aircraft could fly from Iwo airstrips, planes from these carriers would furnish nearly all the close air support for combat troops ashore.107
Simultaneous with the beginning of the Iwo bombardment on 16 February, Admiral Mitscher's Fast Carrier Force had smashed at the Tokyo area of Japan in a covering action to distract enemy attention from American forces attacking the Volcano-Bonins. This strike against the mainland continued through the 17th, when Mitscher withdrew his force to a point from which its might could be brought to bear on Iwo Jima by 19 February.108
By morning of 17 February the weather had cleared and remained excellent throughout the day. At 0840 the Nevada, Idaho, and Tennessee moved in to 3,000 yards from shore to provide close support for the underwater demolition team operations scheduled to begin at 1100.109 While UDT's awaited orders to head for the beach, the covering fire support vessels experienced stiff opposition from enemy shore batteries. At 0840 the Tennessee was hit and about an hour later the cruiser Pensacola rocked under the impact of several direct hits and near misses from heavy-caliber enemy shells. Pensacola suffered extensive damage and 115 casualties. Among the 17 killed was the ship's executive officer.110
At about 1045 the UDT swimmers headed toward the hostile island while LCI(G)'s covered their approach from positions 1,000 yards off shore flailing the beaches with rocket barrages and 40mm gunfire. Working under heavier mortar and small-arms fire than they had ever before experienced, these men proceeded with their assigned tasks in a "business as usual" manner. Their mission included checking beach and surf conditions, searching for obstacles on the beach, and in the water approaches. Obstacles were to be destroyed when found. Some of the swimmers actually crawled out of the water to collect soil samples for examination on board ship.111
As UDT men labored near the beaches, their 12 supporting LCI(G)'s ran into serious trouble. At about 1100 the gunboats suddenly began to receive extremely heavy fire from enemy mortars and previously hidden large-caliber
120MM GUN COMMANDING EASTERN BEACHES. This gun was knocked out prior to D-Day.
fixed artillery.112 Gunboat crews immediately answered these batteries with their own light armament, remaining on station until forced to retire by heavy casualties and severe damage. Vessels most seriously hit withdrew and were replaced by others, thus maintaining constant 40mm fire on enemy batteries. In a 45-minute period beginning at 1100, nine of the 12 gunboats were put out of action and three less seriously damaged by Japanese shellfire.113
Map 3: Naval Gunfire Areas of Responsibility, D-1
The startling opposition offered by enemy guns did not long go unchallenged by large-caliber United States naval weapons. The old Nevada, standing close by to offer watchdog services during the beach reconnaissance, leveled powerful 14-inch rifles on these newly awakened shore batteries and continued heavy, concentrated counterbattery fire until 1240. To furnish much needed concealment to UDT's and stricken LCI(G)'s, the Tennessee, Nevada, and Idaho quickly put down a smoke screen along the entire eastern beach area. Under this protection and the additional covering fire of destroyers, the UDT's withdrew from the beach. By 1220 all members of these teams were recovered and back aboard their APD's (transport-destroyers) where they made their reports. Despite the continuous heavy opposition, they had suffered only one casualty.114
While elements of the four UDT's prepared to conduct a reconnaissance of west coast beaches during the afternoon of 17 February, heavy bombardment ships administered a thunderous pounding to top priority targets on the east coast. Ammunition allotments were revised upward by Admiral Blandy to permit heavier concentrations of fire on eastern beaches, and shell saturated the areas of recently revealed heavy Japanese coast-defense guns. Admiral Rodgers had recommended to Admiral Blandy that all available weapons now be employed in smashing top priority installations around Mount Suribachi and in the high ground north of the eastern beaches. Fire Support Units One and Two (including the Nevada, Idaho, Tennessee, Vicksburg, and Salt Lake City) executed close-range fire missions against these areas during the remainder of the day.115
The UDT examination of western beaches and their approaches, originally scheduled for 1500, did not begin until 1615 because of the unexpected opposition met off the eastern beaches earlier in the day. As during their morning activities, underwater demolition men worked under constant fire from Japanese automatic weapons and rifles.116 At about 1800 the swimmers returned to their APD havens without incurring any casualties.
Results of the morning and afternoon reconnaissances were reassuring. Swimmers reported beach and surf conditions suitable for a landing on either the preferred or alternate beaches. No underwater or beach obstacles existed and the single mine found was destroyed.117
Reconnaissance company Marines (two officers and 20 enlisted men) from the two assault divisions accompanied UDT teams on both beach investigations and later reported to their units aboard command ships at sea. Three enlisted men from Company B, Amphibious Reconnaissance Battalion, Fleet Marine Force, served as observers during UDT operations. With information furnished by these Marines prior to 19 February, regimental and battalion commanders were acquainted with conditions existing on landing beaches assigned their units in the D-Day scheme of maneuver.118
Softening-up activities of aircraft on D-minus-2 accomplished considerably more than on the previous day. This second day of preliminary bombardment gave airmen perfect flying weather, and they took advantage of it by showering destruction on the island from sunrise to sunset. Carrier pilots flew a total of 226 sorties, excluding search and patrol missions. Flyers concentrated on dual-purpose guns and automatic antiaircraft weapons around the airfields, as well as both beach areas in support of UDT operations.
Eight Navy fighters dropped napalm with limited success during the day. Some of the napalm bombs did not release on the first attempts and several failed to ignite upon hitting
the ground. Planes also worked over pillboxes and strafed vehicles. Enemy opposition was intense all day, and heavy antiaircraft fire greeted 42 Army Air Force B-24's that arrived on station over Iwo. These craft dropped their bombs from 5,000 feet, achieving hits in the target area but actually inflicting no known damage to installations.119
The last day of preliminary naval gunfire bombardment began with the job far from finished. Negligible evidence of destruction wrought on enemy defenses during two days of bombardment suggested a modification of firing schedules and assignments. Accordingly, the V Corps Naval Gunfire Officer recommended that a "maximum concentration of bombardment be placed on and near the preferred landing beaches." This proposal received Admiral Blandy's immediate approval.120
A rearrangement of firing units now permitted four battleships and one heavy cruiser to concentrate their entire armament, (5-, 8-, and 14-inch guns) in a blanket bombardment of landings areas (compare Maps 2 and 3). Ships received permission to fire all unexpended ammunition (less that needed for D-Day) weather allowing. Once more nature failed to cooperate during the softening phase. On D-minus-1 visibility was only fair with frequent light rains reducing it to poor.121
At 0745 Admiral Rodgers ordered his ships to "close beach and get going."122 These units immediately moved in to within 2,500 yards of the shore (close range) and opened fire to commence the third day of bombardment. Admiral Blandy issued orders early in the day that the batteries nestled at the foot of Mount Suribachi must positively be destroyed. The same order applied to coast-defense guns emplaced on the rim of a quarry about 400 yards inland north of the East Boat Basin. The Tennessee and Idaho received this vital assignment. The Tennessee sent salvo after salvo into these positions for 43/4 hours, expending a total of 333 rounds. The Idaho, not to be far outdone, fired a total of 280 rounds during the same period of time.123
Friendly aircraft again operated over Iwo Jima on D-minus-1 to assist the naval vessels in their all-out effort to prepare the island for assault the following day. As on the first day of preliminary fires, weather set the tempo of activity for carrier and land-based planes. In early afternoon Seventh Air Force bombers arrived over the island after a long trip from the Marianas, but the B-24's could just as well have remained grounded. Clouds effectively masked the objective and the strike was canceled. Navy flyers from Admiral Durgin's escort carriers directed 28 sorties against positions flanking the landing beaches.124
The last day of preparatory bombardment ended at 1821, 18 February, when close-range fires ceased along the east coast and heavy support ships moved out toward night deployment areas.125 At 2130 the Blessman (APD48), while en route to join her deployment unit for the night, received a bomb hit from a low-flying enemy plane; only one bomb, but it struck a vital area--the troop space above the forward fireroom. In addition to serious material damage, personnel loss was heavy and more tragic than usual. This vessel was carrying members of UDT 15 that had survived the hazardous beach reconnaissance missions of the previous day. Casualties included two killed and 20 wounded among UDT men. The Blessman's own crew suffered 11 wounded.126
Pre-H-Hour bombardment (D-Day fires in preparation for the landing) would give support
PRE-H-HOUR BOMBARDMENT pounds landing beaches and adjacent areas shrouding rest of island in smoke and dust (Navy Photo)
ships another and final opportunity to pummel the enemy defenses before the assault. But the fact was that when heavy support units withdrew from Iwo the evening of 18 February, the softening-up phase had ended. At the close of this third day Admiral Blandy sent the following message to Admiral Turner:
Though weather has not permitted complete expenditure of entire ammunition allowance and more installations can be found and destroyed with one more day of bombardment I believe landing can be accomplished tomorrow as scheduled if necessary. I recommend however, special attention before and during landing to flanks and East Coast of island with neutralizing fire and white phosphorus projectiles immediately available if required. Amplifying report follows immediately.127
Admiral Turner deemed necessary the execution of assault plans without modification and D-Day for Iwo Jima remained 19 February 1945. The preliminary bombardment phase was finished.
Pre-H-Hour BombardmentOn the morning of D-Day emphasis shifted from painstaking fire for destruction to area neutralization and beach preparation. To accomplish this the heavy gunfire support ships were augmented by the gunboat and mortar support groups.128 The big naval guns opened up at 0640, having been reinforced by the 16-inch rifles on the Washington and North Carolina. Five minutes later nine LCI(R)'s commenced launching rockets toward the island. For the next 1½ hours the heavy support and rocket ships fired on targets of opportunity in assigned areas, giving priority to coast-defense and antiaircraft positions to cover the transports as they moved in to debarkation stations. The LCI(R)'s concentrated on the Motoyama Plateau throughout the morning, firing 9,500 5-inch spin-stabilized rockets into that heavily fortified area.
Other support craft added their weight to the bombardment at 0730, showering the slopes of Mount Suribachi and the high ground on the north flank of the beaches with rockets and mortar shells.
Between 0805 and 0825 (H-minus-55 to H-minus 35), while fire-support ships maneuvered into final positions, 120 fighter and bomber planes from Admiral Mitscher's Fast Carrier Force struck fiercely at the landing beaches and adjacent areas. When this air strike was completed, naval guns resumed firing.
Now the tempo increased, with neutralization of beaches as the primary mission. Initially, some air bursts were employed to cut down
defenders who might be in the open, but naval gunners shifted to impact rounds when troop-carrying LVT's passed through the line of firing ships stationed in the boat lanes. Rocket craft again seared landing areas, and the mortar boats shelled inland to a depth of about 1,000 yards. As assault troops neared shore, the naval bombardment shifted ahead and to the flanks and planes returned to give the beach a final pounding.
In previous Pacific assaults, naval gunfire had lifted too far inland when troops landed. The lack of adequate fires close to landing areas had resulted in heavy casualties early in the operation at Saipan. To correct this at Iwo a rolling barrage129 technique was developed and used. Five-inch batteries delivered this fire, maintaining a 400-yard margin of safety to the front of friendly troops by lifting inland in accordance with the best available estimate of troop advance. When the attack did not move forward as rapidly as expected certain blocks (target areas) of prearranged fire were repeated.130
The effectiveness of preliminary bombardment remained little more than conjecture until after H-Hour. Even officers who conducted the softening-up attacks could not positively ascertain the amount of actual preassault damage inflicted on enemy defenses. Excellent camouflage plus unfavorable weather during most of the 3-day period seriously hampered all operations, including spotting and damage analysis. Naval commanders believed, however, that they had destroyed, or at least neutralized, enemy guns capable of placing observed fire on the eastern beaches and their seaward approaches.
Table of Contents ** Previous Chapter (1) * Next Chapter (3)
1. JWPC 91/D, 13Sep43, "Seizure of the Bonins."
2. Iwo Jima is located in the Volcano Islands (Kazan Retto) but early operations plans, as well as several that followed, refer to this island as being part of the Bonin Group.
3. A new JCS directive, issued on 12Mar44, speeded up the Pacific war by assigning new operations and cancelling others. Air attacks on the Marianas, Palaus, and Carolines were to be intensified and seizure of the southern Marianas was firmly scheduled for 15Jun44. JCS 713 and 713/4, 12Mar44.
4. Even before Saipan was secured, a plan was advanced advocating immediate occupation of Iwo. On 24Jun44 a paper prepared by one of the teams of the Joint War Plans Committee discussed immediate seizure of Iwo Jima, utilizing forces assembled for occupation of Guam. JWPC 244, 24Jun44, "Immediate Occupation of Iwo Jima."
5. CinCPOA, Campaign Plan GRANITE II, 3Jun44.
6. JCS 924, 30Jun44.
7. In July 1944 the AAF advised the Joint Planning Staff that Iwo was a potential base for fighter planes since Tokyo would be within the radius of action for P-51's (Mustangs) based on that island. Hence, in view of the predicted need for protecting B-29's over Nippon proper, it was recommended that "plans for the defeat of Japan include operations to capture and develop fighter bases on the Bonin Islands." AAF memorandum for JPS, 21Jul44, "Fighter Escort fo VLR Bombers."
8. JWPC 91/3, 12Aug44, "Plan for the Seizure of the Bonins," notes from JPS 163d meeting 16Aug44.
9. JLC 67/4, 23Aug44, "Memorandum of Request, Naval Personnel Requirements."
10. Ltr, CinCPac, 000106, 11Sep44 to ComGenPOA and ComGen FMFPac.
11. Ltr, ComGenAAFPOA to CinCPac, 11Sep44; Ltr CinCPOA, 000113, to ComFifthFlt, ComGen Tenth Army, ComAmphForPacFlt, 16Sep44; Ltr ComGenPOA, 00013, to CinCPOA, 27Sep44.
12. Ltr Adm R.A. Spruance, USN (Ret) to CMC, 5Jan52.
13. JCS 713/18, 2Oct44, "Future Operations in the Pacific."
14. JCS 713/19, 3Oct44, "Future Operations in the Pacific."
15. Ltr CG FMFPac to CG VAC, 00059, 14Oct44.
16. JPS 404/15, 18Oct44, "Operations for the Defeat of Japan."
17. D-Day had been twice postponed prior to final designation of the 19Feb45 date. See next subchapter.
18. Boggs, 26-28.
19. Disp CinCPOA to JCS, 030215, Dec44.
22. TF 56 Report of Planning, Operations, Iwo Jima Operation, 27Mar45, Encl A. Hereinafter cited as TF 56 OpRpt.
24. Of the three divisions, the 3d was the latest to emerge from combat at this time. Though Guam was called secure by 10 August 1944, savage and tenacious resistance by certain isolated Japanese elements required laborious, and many times costly mopping-up activities until mid-December. Maj O.R. Lodge, The Recapture of Guam, MarCorps Historical Monograph (U.S. Government Printing Office, 1954).
25. For the Task Organization of V Amphibious Corps Landing Force, see Appendix V.
26. For task organization of forces supporting the V Amphibious Corps Landing Force see Appendix VII.
27. 138th AA Group (USA) Special Action Report, Iwo Jima Campaign, 17Mar45, hereinafter cited as 138th AA Group SAR. The group included the 483d AA/AW Bn (automatic weapons) and the 506th AA Gun Bn (90mm guns).
28. 5th Marine Division Action Report, Iwo Jima, 28Apr45, Sec III, 5, hereinafter cited as 5th MarDiv SAR. The 5th Div reserve was now composed of 3/28 and 1/26, leaving the 26th Marines (less 1/26) in VAC reserve until released on 19 Feb.
29. Disp CTG 56.1, 0018, 14Feb45.
30. Amphibious Forces, U.S. Pacific Fleet (CTF 51), Report of the capture of Iwo Jima, 19May45, hereinafter cited as TF-51 Rpt.
31. Regimental Combat Team. The 5th MarDiv called its reinforced regiments Combat Teams (CT's), while the 3d and 4th MarDivs used the term Regimental Combat Teams (RCT's). In this monograph RCT is used for all reinforced regiments.
32. The O-1 line as drawn on the map indicated initial objectives. It was delineated along commanding or conspicuous terrain features where units could be halted for control., coordination, and further orders. This line was designated in the Corps Operation Plan.
33. The VAC LANFOR plan originally called for the use of Beach BLUE 2 as a landing beach in the assault. Because of the proximity of BLUE 2 to the commanding high ground on the right, and in order to provide a safety factor while maintaining adequate neutralization fires on this high ground during the initial landing, the 4th Division requested permission to confine the landing of the 25th Marines to BLUE 1. This permission was granted. The 25th Marines was directed to land on BLUE 1 and seize BLUE 2 rapidly to permit the early use of this beach for succeeding units and supplies. 4th Marine Division Operations Report, Iwo Jima, 18May45, Sec I, 2, hereinafter cited as 4th MarDiv OpRpt.
34. There was one exception to this plan. Company A, 5th Tank Battalion, attached to the 27th Marines, was scheduled to land on the RED Beaches at H-plus-30 minutes. 5th MarDiv SAR, Sec VII, 10.
35. Navy photo work done over Iwo Jima during these strikes was never excelled in later efforts to gain coverage of the target. Aerial photographs taken during the 15Jun44 raids furnished planners with complete and clear pictures of the entire island. They were of special value to intelligence personnel as the enemy did not begin intensive fortification of Iwo until after Saipan fell, and the progress of the Japanese defense build-up could be noted through comparison of mid-1944 aerial shots of Iwo with those taken up to D-Day. Ltr Col G.A. Roll to CMC, 15Dec52, hereinafter cited as Roll.
36. TF 56 IntelRpt.
37. TF 51 Rpt, Pt V, Sec A.
38. TF 56 IntelRpt 3.
39. Ibid., 2.
40. 1st Supplement to Nanpo Shoto Information Bulletin No. 122-44, 10Oct44, CinCPac-CinCPOA Bulletin No. 9-45, 10Jan45.
41. The foregoing remarks on the expected Japanese defensive tactics were taken from Supplement No. 1 to CinCPac-CinCPOA Bulletin No. 122-44, 10Oct44.
42. TF 56 IntelRpt, 4.
43. TF 56 IntelRpt, Appendix A.
44. VAC C-2 Study, 3.
45. Ibid. The foregoing estimates of Japanese strength may be compared with the actual enemy situation by referring to Chapter 1 and Appendix VI of this monograph.
47. 4th MarDiv Support Group, Operation Report, Iwo Jima Operation, 4Apr45, Sec III, hereinafter cited as 4th MarDiv Support Group Rpt; 5th MarDiv SAR, Annex B, Intelligence, 34, hereinafter cited as 5th MarDiv IntelRpt.
48. Ibid., 12.
50. CinCPac-CinCPOA Bulletin No 2-46, 15Feb45, 5.
51. A notebook found on the body of an unidentified enemy soldier on Iwo contained the following information: "The task force will take four days to arrive at Iwo Jima from Saipan. One battleship, 18 cruisers and destroyers, 40 transports left Hawaii. (? and 5th Marine Division) 3d and 4th Marine Division, one brigade." As quoted in TF 56 IntelRpt, Sec III, 9.
52. TF 56 Report of Logistics, Iwo Jima Operation, 31Mar45, 1., hereinafter cited as TF 56 Logistics Rpt; VAC Assistant Chief of Staff, G-4, Special Action Report, Iwo Jima Campaign, 30Apr45, hereinafter cited as VAC Logistics Rpt.
53. TF 56 Logistics Rpt, 5. Materials strapped or fastened on wooden platforms (pallets). Palletization facilitates loading and unloading operations when cranes and other special lifting devices are available to handle these convenient but heavy loads.
54. 4th MarDiv OpRpt, Annex D, Logistics, 2, hereinafter cited as 4thMarDiv Logistics Rpt. The LSM's were oceangoing ships of 165-ton capacity and were about 200 feet long. They could carry five medium tanks each or other heavy vehicles direct to a hostile beach.
55. The fast, maneuverable weasel, with its low silhouette, pulled trailers and artillery pieces over the terrain that wheeled vehicles could not negotiate. Of great value on land, they did not prove very seaworthy. VAC Logistics Rpt, 45.
56. VAC Engineer Special Action Report, Iwo Jima Campaign, 17Apr45, hereinafter cited as VAC EngRpt.
57. VAC OpPlan 3-44, 23Dec44, Annex M. Engineer Plan.
58. For the computation of casualties, it was assumed that: "fourteen (14) days would be required to complete the seizure of the objective; that 5 percent of the entire force would become casualties on each of the first and second days; 3 percent on the third and fourth days; and 1½ percent on each of the remaining ten days; that 20 percent of all casualties would be dead or missing." VAC Surgeon, Special Action Report, Iwo Jima Campaign, 24Mar45, 1, hereinafter cited as VAC MedRpt.
59. TF 56 Medical Report, Iwo Jima, 28Mar45, 1-2, hereinafter cited as TF 56 MedRpt.
60. There were only three APH's commissioned during the war. These craft were designed to accommodate the wounded brought offshore direct from combat. As contrasted with the regular hospital ships, they carried troops and armament; they were not painted white and claimed no immunity under the Geneva Convention. They were named for deceased Surgeons General of the Navy, (Pinkney, Tyron, Rixey). Maj R.O. Hough, The Island War (Philadelphia, 1947), 214.
61. The Ozark (LSV2) was converted in 1944 from a mine layer and equipped with a stern ramp. This vessel of 6,000 tons (455 ft. long), could carry 21 LVT's, 44 DUKW's, or 800 troops. The Ozark lifted 50 preloaded amphibian trailers to Iwo. J.C. Fahey, The Ships and Aircraft of the United States Fleet (Washington, 1950), 33-35.
[NOTE: Most of the information from earlier editions of this work have been incorporated in the "Ships of the United States Navy, 1940-1945" database on HyperWar.]
62. VAC Assistant Chief of Staff, G-1, Special Action Report, Iwo Jima Campaign, 1Mar45, 13, hereinafter cited as VAC Personnel Rpt.
63. TF 56 MedRpt, 2. VAC MedRpt, 16.
64. VAC Personnel Rpt, 13-15.
65. Ibid., 15.
66. TF 56 OpRpt, Encl C.
67. 4th MarDiv OpRpt, Sec I.
68. 28th Marines Action Report, Iwo Jima, undated, Pt. IV. Hereinafter cited as 28th Mar SAR.
69. 3d Marine Division Action Report, Iwo Jima Operation, 30Apr 45, Pt. 2, hereinafter cited as 3d MarDiv SAR.
70. TF 56 OpRpt, Encl. C.
72. The 2d Armored and the 3d and 5th Amphibian Tractor Battalions did not participate. These three units had supported Marianas operations and remained in that area during Hawaiian rehearsals for rehabilitation, re-equipping, and training. They were assigned to assault divisions at Saipan before final exercises. The 10th and 11th Amphibian Tractor Battalions were present. All five LVT battalions participated in the Saipan rehearsals which followed. VAC LVT Officer, Special Action Report, Iwo Jima Campaign, 30Apr45, 2.
73. VAC Artillery Officer's Report, 18Mar45, 9, hereinafter cited as VAC ArtyRpt.
74. 4th MarDiv OpRpt, Sec I. 5th MarDiv SAR, Sec IV.
75. TF 56 OpRpt, Encl C; VAC OpRpt.
76. TF 56 Transport Quartermaster Report on Iwo Jima Operation, 1Apr45, hereinafter cited as TF 56 TQM Rpt. APA's and AKA's embarked about 550 and 2,000 tons of cargo respectively, APA's loading this tonnage in addition to their primary cargo--personnel. VAC Transport Quartermaster Special Action Report, Iwo Jima Campaign, 27Mar45, hereinafter cited as VAC TQM Rpt.
77. VAC TQM Rpt; 3d MarDiv SAR, 45. The 483d AA(AW) Bn (USA), 138th AAGp, loaded at Ulithi, where it had comprised part of the garrison force.
78. VAC TQM Rpt, Encl A.
79. VAC TQM Rpt, 3; 4th MarDiv Logistics Rpt.
80. Understowed, preloaded cargo consisted of items loaded in ships or craft in addition to the primary cargo, which might be tanks or vehicles. Supplies loaded in an LST tank deck would be covered with dunnage and primary cargo loaded on top. Preloaded supplies could be stowed in any available space from which they could be quickly discharged when landing ship or craft beached.
81. VAC Logistics Rpt.
82. TF 56 TQM Rpt.
83. Commander in Chief United States Fleet, Amphibious Operations, Capture of Iwo Jima, 16Feb to 16Mar45, P-0012, 17Jul45, 1-5, hereinafter cited as CominCh P-0012.
84. VAC OpRpt, 9.
85. Ibid.; 3d MarDiv SAR, 4.
86. TF 56 Report of Air Operations in Support of the Capture of Iwo Jima, 4Apr45, 1, hereinafter cited as TF 56 Air Rpt.
87. These B-24's were from the 11th Group on Guam and the 30th Group on Saipan. Two squadrons hit Iwo daily, primarily with 500-pound general purpose bombs, from 8 December until D-Day. Army Air Forces, Pacific Ocean Areas, Report of Participation in the Iwo Jima Operation, 1945, 75.
88. Ibid., 76.
89. CTF 51 OpPlan A25-44, Annex I.
90. TF 51 Rpt, Pt V, Sec E, 17-18.
91. CominCh P-0012, 301.
92. TF 56 Preliminary Report on Naval Gunfire Support in Operations against Iwo Jima, 1Apr45, 4, hereinafter cited as TF 56 Preliminary NGF Rpt; DETACHMENT. On 15Nov44 Admiral Turner informed V Corps that CinCPOA's initial plan for preparation fires was changed. Instead, one cruiser division would shell Iwo on 15 December and at irregular intervals thereafter. This was the substitute for five continuous days of bombardment by a cruiser division. Then, on D-minus-3, the Amphibious Support Force, including seven battleships, would commence a "methodical and thorough bombardment." Ltr ComPhibsPac to CG VAC, 000209, 15Nov44.
93. Ltr CG VAC to ComPhibsPac 0009B, 2Jan45, 1st endorsement, 6Jan45; 2d endorsement, 9Jan45; Ltr ComFifthFlt to CG FMF Pac, 00036, 12Jan45.
94. Ltr ComFifthFlt to ComPhibsPac, 00066, 2Dec44; Ltr ComPhibsPac to ComGenVAC, 000209, 15Nov44.
95. Vessels of TF 54 were assigned to TF 52 for execution of shore bombardment at the objective. Gunfire and Covering Force (TF 54) Report of Operations of Task Force 54 in the Iwo Jima Campaign, 10Mar45, hereinafter cited as TF 54 OpRpt.
96. Amphibious Support Force (TF 52) Action Report, Iwo Jima, 23Feb45, 3-4, hereinafter cited as TF 52 SAR.
97. Heavy support vessels for this revised naval gunfire plan came from great distances and many stations. In November 1944, the Nevada, Texas, Arkansas, and Tuscaloosa reached the Pacific through the Panama Canal after supporting landings in North Africa, Normandy and Southern France. The New York, after supporting North African landings and operating on Atlantic convoy duty, also reached the Pacific by way of the Panama Canal in November and joined 5th Fleet units at Ulithi. The Idaho and Tennessee both joined Iwo Jima bombardment units directly from the West Coast shipyards where each had undergone badly needed repairs after extensive prior Pacific operations. The Vicksburg, commissioned in June 1944, participated in her first combat operation at Iwo. The Pensacola, Chester, and Salt Lake City (CruDiv 5, RAdm Allen E. Smith, USN) had been shelling Volcano-Bonin Islands intermittently since November 1944. Office of Naval Records and Library, Ships' Histories Branch, Navy Department, U.S. Navy Ships' Histories. Hereinafter cited as Ships' Histories.
98. TF 52 SAR, 3-4.
99. Fast Carrier Force (TF 58) U.S. Fifth Fleet, Report of Combat Operations from 10Feb45 to 4Mar45, 13Mar45. The Fast Carrier Force was designated TF 38 when operating under the Third Fleet, and TF 58 while operating under Fifth Fleet command. This dual designation of TF 38/58 paralleled that of the Third and Fifth Fleets, of which Admiral Halsey later wrote, "Instead of the stagecoach system of keeping the drivers and changing the horses, we changed drivers and kept the horses." Fleet Admiral W.F. Halsey, USN, and Lieutenant Commander J. Bryan, III, USNR, Admiral Halsey's Story, (New York, 1947), 197, 247.
100. TF 54 OpRpt, 6.
101. Tennessee, Idaho, New York, Nevada, Arkansas, Chester, Salt Lake City, Tuscaloosa, Pensacola, Vicksburg.
102. TF 52 SAR, 11.
103. Ltr Adm W.H.P. Blandy, (Ret), to CMC, 20Jan53; air observers from the 3d, 4th, and 5th MarDivs, assigned to fire support ships, spotted targets for Navy guns. Also, Navy VOC-1 (fighter-spotter squadron) flew from the CVE Wake Island to locate targets for TF 54. The Iwo operation saw the first employment of VOF (Navy fighter planes) aircraft for spotting assignments in the Pacific area. Organization of VOC-1 was prompted by experience in use of fighter-type planes for spotting during invasions of Africa, Sicily, and Italy. Composite Spotting Squadron One, Participation of VOC-1 in Iwo Jima Operation, 18Mar45, 1; Naval Gunfire Officer, Expeditionary Troops, Fifth Fleet, Report on Naval Gunfire Support in Operations Against Iwo Jima, 9Jun45, 2, hereinafter cited as TF 56 Final NGF Rpt.
104. CominCh P-0012, 1-2.
105. TF 54 OpRpt, 9; VAC NGF Rpt, 7.
106. TF 52 SAR, Encl D, 3.
107. USS Makin Island Action Report, Occupation of Iwo Jima, 10Feb45 to 11Mar45, undated; Ships' Histories, USS Wake Island, USS Petrof Bay, USS Steamer Bay.
108. TF 56 Air Rpt, 2.
109. TF 52 SAR, Encl (I), 1; TF 54 OpRpt, 10.
110. Ibid. Damage to Pensacola included a burned observation plane, three compartments flooded, combat information center rendered inoperative, catapult damaged, one 5-inch gun out of action and sickbay flooded. This ship received six enemy shells, TF 52 SAR, 6-7, Pt G, 1.
111. TF 52 SAR, Pt C, 1; Ltr Cdr D.L. Kauffman, USN, to author, 13Jan53. Cdr Kauffman commanded the UDT unit and served as chief of staff to Capt Hanlon, UDT Group Commander at Iwo Jima.
112. An interesting opinion by a victim of these guns, who was brought aboard the Nevada from LCI(G)-441, throws some light on why the enemy revealed the location of his most powerful beach defenses prior to D-Day. His conclusions were that the guns opened fire as soon as rockets were launched and since this was the first time rockets were used in support of pre-D-Day UDT operations, the enemy assumed the reconnaissance to be an actual landing attempt. TF 54 OpRpt, 24.
113. Damaged LCI(G)'s: 474, 441, 473, 438, 449, 457, 466, 471, 450, 346, and 348. This LCI group suffered 170 casualties at Iwo--132 wounded and 38 killed in action. Shell fragments later recovered from these craft indicated that the heaviest enemy shore batteries firing on the group were guns of about 150mm. TF 52 SAR, Encl G, H. Of the officer commanding these 12 gunboats of LCI(G) Group Eight, LCI(G) Flotilla Three, one received the Medal of Honor, ten received the Navy Cross, and the Unit was awarded the Presidential Unit Citation for this action of 17 February. Navy Department Press and Radio Release, 5Sep45.
114. TF 54 OpRpt, 10; TF 52 SAR, 7, Pt A, 38, Pt G, 2, Pt C, 4; TF 51 Rpt, Pt V, Pt G, 3, 5.
115. TF 54 OpRpt, I 10; TF 51 OpPlan, Change No Three, Annex H.
116. TF 51 Rpt, Pt V, G.
117. TF 52 SAR, 7, 8.
118. VAC Headquarters Commandant, Special Action Report, Iwo Jima Campaign, 30Mar45, Encl A; 4th MarDiv Support Group Rpt, Pt IV, 9; 5th MarDiv IntelRpt, 34.
119. TF 52 SAR, Encl I, 1.
120. VAC NGF Rpt, 15; TF 54 OpRpt, 1.
121. VAC NGF Rpt, 15.
122. TF 54 OpRpt, 11.
123. VAC NGF Rpt, 15.
124. During this 3-eay period of activity carrier planes flew a total of 612 sorties against ground targets on Iwo Jima. Only three were lost to enemy ground fire, and the crewmen of these were rescued. TF 52 SAR, Encl D, 9.
125. TF 54 OpRpt, 12.
126. TF 51 Rpt, Pt IV, 13: TF 52 SAR, encl H, 1. This attack on 18 Feb was the only raid by enemy aircraft to cause damage to American units at or near Iwo during the pre-D-Day operations. Other contacts resulted in the downing of one Zeke (single-engine Japanese fighter) over the island by an OS2U from the Pensacola (CA24) at 0830 16 Feb, and destruction of one enemy twin-engine bomber by the antiaircraft guns of the Halligan (DD584) on picket duty 80 miles north of Iwo. TF 51 Rpt, Pt IV, Sec B.
127. Message CTF 52 to CTF 51, NCR 60303, 18Feb45.
128. This powerful flotilla of support craft totaled 42 vessels: 12 Landing Craft, Support (large) [LCS(L)'s] armed with 4.5-inch rockets and 40mm guns; three Landing Craft, Infantry (gunboat) [LCI(G)'s] with similar armament; 18 Landing Craft, Infantry (mortar ship) [LCI(M)'s] armed with 4.2-inch mortars; and nine Landing Craft, Infantry (rocket ship) [LCI(R)'s] armed with 5-inch rockets. VAC NGF Rpt, 25, 26.
129. A true definition of the term rolling barrage, as used in WW I, is artillery fire in which the range increases regularly according to a definite time schedule. This schedule was adhered to rigidly and it was the responsibility of infantry commanders to keep their troops from advancing faster than the time allowed for lifting artillery fire to the next range. On Iwo Jima, however, although the fire was called a rolling barrage and set upon a time schedule, air observers reported troop progress and fire was adjusted in accordance with troop advances.
130. VAC NGF Rpt, 23.