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Chapter 2: Offensive Plans and Preparations1

Preliminary planning for the seizure of an objective in the Volcano–Bonin Islands began as early as September 1943, when the Joint War Plans Committee, a planning agency of the Joint Chiefs of Staff, advocated such a move.2 However, because of impending military operations in the Gilberts, Marshalls, and Marianas no further preparation for any operations against the Bonins were made until the summer of 1944. The successful completion of the Saipan operation in July brought the continuation of operations in the Central Pacific into sharper focus. In a conference held in Washington by top echelon U.S. military leaders from 13-22 July 1944, the senior members of the Joint War Plans Committee presented to the Joint Chiefs the possible courses of action in continuing the war against Japan. Plans for the bombing of the Japanese home islands figured prominently in these discussions. In this connection, the use of the Marianas as a base for long-range bombers was again discussed, as well as the need for seizing the Bonins to facilitate such air operations.3

In the course of a visit to Hawaii in mid-July 1944, Admiral Ernest J. King discussed with Admiral Chester W. Nimitz some of the decisions which the Joint Chiefs had reached. He apprised Nimitz of the fact that the Army Air Forces had been ordered to set up four B-29 groups in the Marianas for long-range bombing. In time, 12 groups of B-29s were to be based in the Marianas. In this connection, King brought up the desirability of establishing bases in the Bonins to furnish fighter escorts for the B-29s. With operations

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in the Carolines and the Philippines scheduled within the next few months, both naval commanders felt that no forces should be diverted to the Bonins at this time. Nevertheless, King instructed Nimitz to prepare plans for an assault against the Bonins, although he considered such an operation unwise unless it was shortly followed by an invasion of Japan.

Planning for an amphibious assault against the Bonins was inextricably interwoven with the development of the B-29 long-range bomber of the U.S. Army Air Forces, and for this reason an explanation of the development and characteristics of this aircraft appear warranted. The B-29 had its origin in 1939, when General H. H. Arnold, then Chief of the Army Air Corps, ordered the experimental development of a four-engine bomber with a range of 2,000 miles. As eventually developed, the B-29 or “Superfortress” had a wing span of slightly more than 141 feet, a length of 99 feet, and four Wright engines with turbo-superchargers developing 2,200 horsepower each at sea level. The giant bomber was armed with a dozen .50 caliber machine guns and a 20-mm cannon mounted in the tail. The B-29 had a service ceiling of 38,000 feet and near that altitude had a maximum speed of 361 miles per hour. Without a load, the aircraft was estimated to have a range of 4,400 miles; it could move 3,500 miles when carrying a bomb load of four tons.4

During the latter half of 1944, about 100 B-29s operated from airfields in China under the Army Air Forces XX Bomber Command. This command, for all practical purposes, constituted an experimental organization, designed to serve as a prototype for similar units to be activated later. Its mission was three-fold: to test the B-29 under combat conditions; to formulate and refine a tactical doctrine; and to perfect the administrative structure to support the B-29 strikes. By mid-October 1944, China-based B-29s had flown a total of 10 missions against a variety of industrial targets ranging from Bangkok in southeast Asia to Manchuria and the home islands.

Meanwhile, the progress of the American offensive in the Central Pacific had resulted in the capture of the Marianas. Preparations got under way for a sustained bomber offensive against the home islands by Marianas-based B-29s. It was anticipated that the first airfield in the Marianas capable of accommodating the big B-29s would be operational by October 1944. In connection with the initiation of very long-range bombing of the Japanese home islands from B-29 bases in the Marianas, the Volcano-Bonin Islands, situated halfway between the Marianas and Tokyo, assumed major strategic importance. As part of this island group, Iwo Jima appeared the logical choice for invasion because it was the only island suitable for the construction of airfields of sufficient size to handle the new Superfortresses. In this connection, it was not intended to use Iwo as a base or staging area for the B-29s, but as a forward air station from which fighters could fly escort missions for the big bombers. At the same time, crippled

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B-29s limping back from raids over Japan would be able to make emergency landings on the island instead of ditching into the Pacific. Even while the battle for Saipan was in full swing, 500 of the giant bombers were ready for combat.

As increasing attention focused on bases in the Marianas, the strategic importance of the B-29 bases in China waned. As early as September 1944, General Arnold had seriously considered transferring the XX Bomber Command to a more profitable site. Japanese gains in China ultimately forced the abandonment of the B-29 bases and transfer of the B-29 combat groups and their supporting units to the Marianas.

In July 1944, the Army Air Forces advised the Joint Staff Planners that Iwo was a potential base for fighter planes, since Tokyo would be within the range of P-51 Mustangs based on Iwo.5 On 12 August, the Joint War Plans Committee recommended the seizure of the Volcano-Bonins, listing as major reasons their availability for bases from which fighter cover could be provided to support the air effort against Japan; denial of these strategic outposts to the enemy; furnishing air defense bases for American positions in the Marianas; and providing fields for staging heavy bombers against Japan.6

In a study of naval personnel requirements prepared by the Joint Planning Staff in late August 1944, a list of projected operations included an assault against the Volcano-Bonin Islands with a target date of mid-April 1945. It was estimated that three divisions would be required for these operations.7 While planning an invasion of Formosa, Admiral Nimitz also was attracted to the Volcano-Bonin Islands. In September 1944, he informed Lieutenant General Holland M. Smith, Commanding General, Fleet Marine Force, Pacific, that the 2nd and 3rd Marine Divisions should be retained in the Marianas as an area reserve for Formosa. In addition, they were to make up the bulk of the landing force once an attack was mounted against Iwo Jima.

By this time, key service commanders were beset by serious doubts with respect to a major operation against Formosa. Lieutenant General Millard F. Harmon, Commanding General, Army Air Forces, Pacific Ocean Areas, advocated that Formosa be bypassed in favor of the Volcano-Bonins and Ryukyus. His superior, Lieutenant General Robert C. Richardson, Jr., Commanding General, Army Forces, Pacific Ocean Areas, likewise failed to see any advantage in seizing Formosa and expressed himself in favor of advancing through the Nanpo Shoto. Admiral Nimitz felt that the capture of Formosa could serve a useful purpose only if it was a preliminary step towards subsequent landings on a coast of China, where recent Japanese military gains made such a move of questionable value.

Despite an increasing rejection of Formosa as an invasion target by the military leaders concerned, Admiral

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King, Commander in Chief of the U.S. Fleet, consistently adhered to the projected operation against that island, at least until early October 1944. However, on 11 and 12 July, when Admirals King and Nimitz visited Saipan, King asked Admiral Raymond A. Spruance what objective he would recommend for his next operation. Spruance replied that he would like to take Okinawa.8

Admiral Spruance has described his participation in the early planning and the final change of objectives in the following words:–

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 thought Iwo Jima, followed by Okinawa, would be preferable, but was told that the orders from Cominch called for Formosa.9

Following this conversation, Admiral Spruance went on leave. He was about to return to Pearl Harbor during the latter part of September, when he was ordered to attend a conference between Admiral King and Admiral Nimitz which was to be held towards the end of the month at San Francisco. Admiral Spruance recalled the focal points of this meeting as follows:–

At this Conference Admiral Nimitz presented a paper—prepared, I believe, by Captain Forrest Sherman, U.S.N., 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, U.S.A., 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 JCS who approved it.10

The Joint Chiefs of Staff lost little time in issuing a new directive on 3 October ordering Admiral Nimitz to provide fleet cover and support for General MacArthur’s forces in the occupation of Luzon, scheduled for 20 December 1944; to occupy one or more positions in the Nanpo Shoto, with a target date of 20 January 1945; and to occupy one or more positions in the Nansei Shoto by 1 March 1945.11

Subsequently, delays encountered in operations in the Philippines affected planning for the Iwo Jima and Okinawa Operations, which were designated DETACHMENT and ICEBERG, respectively. Target dates had to be readjusted to 19 February for the Iwo operation, and to 1 April for the invasion of Okinawa.

On 7 October Admiral Nimitz and his staff issued a staff study for preliminary planning, which clearly listed the objectives of Operation DETACHMENT. The overriding purpose of the operation was to maintain unremitting military pressure against Japan and to extend American control over the Western Pacific. In American hands, Iwo Jima could be turned into a base from which

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we could attack the Japanese home islands, protect our bases in the Marianas, cover our naval forces, conduct search operations of the approaches to the Japanese home islands, and provide fighter escort for very long-range operations. Three tasks specifically envisioned in the study were the reduction of enemy naval and air strength and industrial facilities in the home islands; the destruction of Japanese naval and air strength in the Bonin Islands, and the capture, occupation, and subsequent defense of Iwo Jima, which was to be developed into an air base.

On 9 October, General Holland Smith received the staff study, accompanied by a directive from Admiral Nimitz ordering the seizure of Iwo Jima. This directive designated specific commanders for the operation. Admiral Spruance, Commander, Fifth Fleet, was placed in charge as Operation Commander, Task Force 50. Under Spruance, Vice Admiral Richmond Kelly Turner, Commander, Amphibious Forces, Pacific, was to command the Joint Expeditionary Force, Task Force 51. Second in command of the Joint Expeditionary Force was Rear Admiral Harry W. Hill. General Holland Smith was designated Commanding General, Expeditionary Troops, Task Force 56.

It was not accidental that these men were selected to command an operation of such vital importance that it has since become known as “the classical amphibious assault of recorded history.”12 All of them had shown their mettle in previous engagements. One chronicler of the Iwo Jima operation put it in the following words:–

The team assigned to Iwo Jima was superb—the very men who had perfected the amphibious techniques from Guadalcanal to Guam. Nearly every problem, it was believed, had been met and mastered along the way, from the jungles of Guadalcanal up through the Solomons, and across the Central Pacific from the bloody reefs of Tarawa to the mountains of the Marianas.13

For General Smith, who was 62 years old, the Iwo Jima operation was to be his last. In mid-October 1944, Smith issued a letter of instruction designating Major General Harry Schmidt, Commanding General, V Amphibious Corps, as Commander of the Landing Force, Task Group 56.1. General Schmidt, 58 at the time, was a veteran of nearly 26 years of military service, who had commanded the 4th Marine Division during the invasion of Roi-Namur in the Marshalls and during the Saipan operation in the Marianas. His experienced staff, headed by Colonel William W. Rogers,14 was responsible for the preparation and execution of all Landing Force plans for the operation. When completed, plans for the execution of the landing had to be submitted by the commander of the landing force to General Smith for the latter’s approval. on 20 October 1944, VAC received a directive from FMFPac, assigning troops to the corps for training, planning, and operations. Initially, the

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corps was to be ready in all respects for combat by 15 December.15

The major units assigned to the Landing Force were the 3rd, 4th, and 5th Marine Divisions. The 3rd Marine Division had already distinguished itself on Bougainvillea in the Solomons and on Guam in the Marianas. While planning for Operation DETACHMENT was in progress during the late autumn of 1944, the division was still reorganizing on Guam after the heavy fighting for that island and was actively engaged in rounding up or dispatching Japanese that continued to infest the island. At the age of 47, the division commander, Major General Graves B. Erskine, was one of the youngest generals in the Marine Corps with a well-established reputation for toughness. Joining the Marine Corps Reserve in 1917 as a second lieutenant, Erskine had distinguished himself in France during World War I. Following the war, he had seen service in Haiti, the Dominican Republic, Nicaragua, and China.

At the time of the Pearl Harbor attack, he served as Chief of Staff of the Amphibious Corps, Atlantic Fleet. In 1942, he was assigned as Chief of Staff of the Amphibious Corps, Pacific Fleet, under Holland Smith, who was then a major general. After taking part in the amphibious training of Army troops for the Kiska and Attu operations in the Aleutians, Erskine became Deputy Corps Commander and Chief of Staff of the V Amphibious Corps when it was organized in 1943. He had an active part in planning the seizure of Tarawa and accompanied the assault forces which took Kwajalein, Saipan, and Tinian. When the Fleet Marine Force, Pacific, was organized after the capture of Saipan, General Erskine became Chief of Staff of that organization. Promoted to the rank of major general in October 1944, he assumed command of the 3rd Marine Division at that time.16

The 4th Marine Division, commanded by Major Clifton B. Cates, also had seen considerable action. During the invasion of Roi-Namur in the Marshalls, it had been the first Marine division to go directly into combat from the United States.17 In less than a year’s time, the division had taken part in three landings. In addition to the Roi-Namur operation, the 4th had also made assault landings on Tinian and Saipan. The forthcoming invasion of Iwo Jima would be the division’s fourth landing in less than 13 months.

General Cates had assumed command of the division on 12 July 1944, when General Schmidt became the Commanding General of the V Amphibious Corps. Cates already had a long and distinguished Marine Corps career behind him, having served in France during World War I as a company grade officer. During his 20 months of service with the 6th Marines he had been wounded in action twice and had earned the Navy Cross, in addition to other decorations. At Guadalcanal early in World War II, he had commanded the 1st Marines, one of the two assault regiments that landed on the island.

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In contrast to the 3rd and 4th Marine Divisions, the 5th Division had not seen combat as a unit prior to the Iwo Jima operation. Organized at Camp Pendleton, California, on 11 November 1943, the division was commanded by Major General Keller E. Rockey. Like his counterparts in the 3rd and 4th Marine Divisions, General Rockey had seen combat action at Chateau Thierry in 1918. Even though the 5th Marine Division had no previous combat experience, nearly half of the men comprising the unit had served with other combat units. In speaking of the division after the end of World War II, General Rockey made the following comment:–

From its earliest days to the hour of its disbandment, I found the 5th to possess and maintain a high standard of military performance and an esprit exceptionally fine. And when the 5th Division entered combat, it acted from the first hour like a unit of veterans. It fought that first fight with the utmost vigor, courage, and intelligence.18

At the time that final plans and preparations for operation DETACHMENT were being made, the 3rd Marine Division was still stationed on Guam, following the recent recapture of that island. AS commander of VAC, General Schmidt had also located his command post on that island. The 4th Marine Division, upon completion of operations on Saipan and Tinian in the Marianas, had returned to its permanent camp site on Maui in Hawaii. In August 1944, the 5th Marine Division had moved from California to Hawaii, where it underwent final training. The close proximity in which the 4th and 5th Marine Divisions found themselves in Hawaii during the latter part of 1944 was to have a favorable effect on joint planning between the divisions. When General Schmidt moved VAC headquarters to Pearl Harbor on 13 October, the major planning staffs concerned with Operation DETACHMENT, except for the 3rd Marine Division, now were functioning close to each other, a circumstance that resulted in better coordination of efforts.

Of the three divisions scheduled to participate in DETACHMENT, the 3rd Marine Division was the only one still actively engaged in military operations during the planning phase for Iwo Jima. Even though Guam had been officially declared secure by 10 August 1944, Marines continued to round up or annihilate stragglers until mid-December. The situation on Guam was not without effect on the planning for Iwo Jima and resulted in one of the changes in the basic operations plan. As General Holland Smith was to reminisce at a later time, with reference to the status of the 3rd Marine Division:–

It had been proposed to hold the division in reserve, alerted at Guam. On further study, I considered it much sounder for this division to arrive with the other troops in the target area on D-Day, available as a floating reserve. This decision proved sound because we ran into a larger garrison and far stronger defenses than we had anticipated.19

General Schmidt issued the first blueprint for Operation DETACHMENT on 19 October 1944, to be used as a guide by subordinate commanders. On the following day, General Smith directed him to have the VAC ready for

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Operation DETACHMENT by 15 December.20

During the two remaining months of 1944, VAC evolved tactical and logistical plans in joint conferences with all commanders concerned. As increasing intelligence became available, alternate plans were drafted and changes were incorporated into the original plan.21 All commanders issued tentative drafts of their respective operation plans, and continual adjustments were made to achieve maximum support with the forces available and to organize the most effective assault force possible. Planning remained flexible right up to D-Day, which itself was postponed twice because the naval forces required for the invasion of Iwo Jima were still engaged in the Philippines. As a result, on 18 November D-Day was postponed to 3 February 1945; on 6 December, an additional postponement to 19 February became necessary.22

When Admiral Spruance assumed command of all forces assigned to the Central Pacific Task Force on 26 January, CinCPOA Plan 11-44 was in full effect. Designated for the beach assault were the 4th and 5th Marine Divisions, less the 26th Marines, which was to be held in Landing Force reserve. For training purposes prior to the operation, the 26th Marines would remain with the 5th Division. The 3rd Marine Division was to stage on Guam and would remain as reserve on board ship in the objective area until D plus 3.

The VAC scheme of maneuver for the landings was relatively simple. The 4th and 5th Marine Divisions were to land abreast on the eastern beaches, the 4th on the right and the 5th on the left. When released to VAC, the 3rd Marine Division, as Expeditionary Troops Reserve, was to land over the same beaches to take part in the attack or play a defensive role, whichever was called for. The plan called for a rapid exploitation of the beachhead with an advance in a northeasterly direction to capture the entire island. A regiment of the 5th Marine Division was designated to capture Mount Suribachi in the south.23

Since there was a possibility of unfavorable surf conditions along the eastern beaches, VAC issued an alternate plan on 8 January 1945, which provided for a landing on the western beaches. However, since predominant northerly or northwesterly winds caused hazardous swells almost continuously along the southwest side of the island, it appeared unlikely that this alternate plan would be put into execution.24

The eastern beaches over which the landings were to be made extended for about 3,500 yards northeastward from Mount Suribachi to the East Boat Basin. (See Map 26). For purposes of organization and control of the invasion force, these beaches were divided into seven

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Map 26: Landing 
Plan—Iwo Jima

Map 26: Landing Plan—Iwo Jima

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500-yard segments, which, from left to right, were designated as Green, Red 1 and 2, Yellow 1 and 2, and Blue 1 and 2. The 5th Marine Division, landing over Green, Red 1, and Red 2 beaches, was to advance straight across the island, which at this point formed a narrow isthmus, until it reached the west coast. At the same time, it was to hold along the right, while part of the division wheeled to the south to capture Mount Suribachi. The 4th Marine Division had the specific mission of moving into the center of the isthmus, while its right flank swerved to the north to seize Motoyama Plateau, the high ground above the East Boat Basin. Unless this vital ground to the north of the invasion beaches and Mount Suribachi to the south—terrain features which overlooked the beaches and permitted the enemy to fire at the exposed Marines at will—were quickly seized, the landing force could be expected to take very heavy casualties.

Once the southern portion of Iwo Jima had been secured, the two divisions could join in a combined drive to the north. At this time, the 3rd Marine Division, initially in Expeditionary Troop Reserve on board ships near the beachhead, could be disembarked and landed to assist in maintaining the momentum of the VAC attack.

The detailed scheme of maneuver for the landings provided for the 28th Marines of the 5th Marine Division, commanded by Colonel Harry B. Liversedge, to land on the extreme left of the corps on Green 1. On the right of the 28th Marines, the 27th, under Colonel Thomas A. Wornham, was to attack towards the west coast of the island, then wheel northeastward and seize the O-1 Line. Action by the 27th and 28th Marines was designed to drive the enemy from the commanding heights along the southern portion of Iwo, simultaneously securing the flanks and rear of VAC. As far as the 4th Marine Division was concerned, the 23rd Marines, commanded by Colonel Walter W. Wensinger, was to go ashore on Yellow 1 and 2 beaches, seize Motoyama Airfield No. 1, then turn to the northeast and seize that part of Motoyama Airfield No. 2 and the O-1 Line within its zone of action. After landing on Blue Beach 1, the 25th Marines, under Colonel John R. Lanigan, was to assist in the capture of Airfield No. 1, the capture of Blue Beach 2, and the O-1 Line within its zone of action.25 The 24th Marines, under Colonel Walter I. Jordan, was to be held in 4th Marine Division reserve during the initial landings. The 26th Marines , led by Colonel Chester B. Graham, was to be released from corps reserve on D-Day and prepared to support the 5th Marine Division.

Division artillery was to go ashore

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on order from the respective division commanders. The 4th Marine Division was to be supported by the 14th Marines, commanded by Colonel Louis G. DeHaven; Colonel James D. Wailer’s 13th Marines was to furnish similar support for the 5th Marine Division.

The operation was to be so timed that at H-Hour 68 LVT(A) 4s, comprising the first wave, were to hit the beach. These vehicles were to advance inland until they reached the first terrace beyond the high-water mark. The armored amphibians would use their 75-mm howitzers and machine guns to the utmost in an attempt to keep the enemy down, thus giving some measure of protection to succeeding waves of Marines who were most vulnerable to enemy fire at the time they debarked from their LVTs. Though early versions of the VAC operations plan had called for tanks of the 4th and 5th Tank Battalions to be landed at H plus 30, subsequent studies of the beaches made it necessary to adopt a more flexible schedule. The possibility of congestion at the water’s edge also contributed to this change in plans. In the end, the time for bringing the tanks ashore was left to the discretion of the regimental commanders. Company A of the 5th Tank Battalion attached to the 27th Marines was scheduled to land on the Red Beaches at the prearranged time of H plus 30 minutes.26

In the event that the landings took place on the western beaches of Iwo, the alternate plan made provision for a company of the 24th Marines, reinforced by a platoon of armored amphibians from the 2nd Armored Amphibian Battalion, to seize Kangoku Rock, a 600-yard-long island lying about 2,200 feet northwest of Iwo Jima. The island could be used as an artillery site and for this reason a contingency plan was prepared to land the 105-mm howitzers of 4/14 there.

Intelligence Planning27

The scheme of maneuver for the Iwo Jima operation, as well as the preliminary planning, was largely based on available intelligence. Enemy documents seized on Saipan during the summer of 1944 gave a fair indication of enemy strength in the Volcano-Bonin Islands. Captured Japanese maps, supplemented by aerial photographs obtained by U.S. Navy carrier pilots during the air strikes of June and July 1944, were utilized in the preparation of situation maps and beach studies. During the planning phase for the operation, pilots of Navy Photographic Squadrons 4 and 5 and the Army Air

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Forces 28th Photographic Reconnaissance Squadron flew 371 sorties. Liberators of the Seventh Air Force obtained additional photographic coverage of the island in the course of their bombing missions.

Significantly, during the preparatory phase, representatives of the 3rd, 4th, and 5th Marine Divisions, the Commander, Amphibious Forces, Pacific, and VAC combined their efforts in preparing a Joint Situation Map which was completed on 6 December 1944. Representative officers from Navy and Marine units were ordered to report to Photographic Interpretation Squadron 2, based on Guam, in late January 1945. There, the most recent photographs were available. On the basis of the most current information then available, a final enemy installations map was prepared that was to play a major part in the pre-D-Day naval and aerial strikes, as well as during the actual assault phase.28

Between 29 November and 2 December 1944, the submarine USS Spearfish conducted a reconnaissance off Iwo Jima. Approaching as close to the island as he could without being detected, the submarine commander gave a running account of the view that presented itself to his eyes as he watched through his periscope. This commentary was transcribed. So close did the submarine approach the shore of Iwo that at one point the skipper spotted a cave going into the base of Mount Suribachi “with a dejected looking individual sitting in the entrance sunning himself.”29 Additional observations included construction work at various parts of the island, an armored car in motion, and various earthworks and block houses on different parts of the island. The submarine reconnaissance failed to discover any guns or emplacements on the slopes of Mount Suribachi itself, nor could individual pillboxes be identified, though a number of caves were visible.30

Beach studies indicated that movement over the loose sand would be difficult for wheeled vehicles; tracked vehicles were not expected to bog down. Partially buried gasoline drums, observed at the edge of the water both on the eastern and western beaches, gave rise to considerable speculation. It was thought that these drums might be wired for electrical ignition, so that burning gasoline would run out over the water to check landing craft, or that they would ignite at the moment the amphibious tractors or tanks reached land to raise a wall of fire before them. It was also possible that the drums had been converted into mines, equipped with pull-type detonators, with attached trip wires, which would ignite when either personnel or tanks came into contact with the wire.31

In any case, Marines were warned to expect the widespread employment of antitank mines and obstacles, combined with “close quarter attack units” using hand-placed charges. No change in

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Japanese artillery tactics was anticipated. Even though the presence of a large number of artillery pieces on the island was a foregone conclusion, there was no reason to believe that the Japanese would employ massed fires in larger than battery concentrations.

From a thorough study of aerial photographs and a captured map showing the scheme of the enemy’s defense, it was known that the Japanese had established an elaborate defense in depth. Gun positions were sited to place withering fire on the selected beaches; defensive works such as pillboxes, blockhouses, antitank trenches, and mines were located where they could repel the American advance once the invasion force had landed. Numerous antiboat gun positions as well as coast defense guns were discovered. Unless these guns were neutralized, it was more than likely that the enemy would use them to fire on the leading waves and transport areas of the invasion force.

Planners for the invasion of Iwo Jima further deduced from documents captured on Saipan that the enemy would adhere to his older tactics of attempting the destruction of the invasion force before an adequate beachhead had been established. The most likely time for this counterattack was considered the early morning of the day following the initial landing.32

Further study of aerial photographs and captured documents indicated that Iwo had probably been divided into four defense sectors with one infantry battalion manning each sector. Since the Japanese were believed to have nine infantry battalions on the island, this would leave five battalions to be held in reserve. Photographs taken in January 1945, as the invasion date was drawing closer, indicated that the number of field fortifications, pillboxes, and covered artillery positions was increasing despite intensive aerial bombardment. A most significant development noted in these photographs was the construction of a line of defense across the island from a point near Hiraiwa Bay on the northwest coast to high ground north of the East Boat Basin.

During the period from 3 December 1944 to 10 February 1945, it was noted that the number of enemy coast defense guns on the island increased from 3 to 6; the number of dual purpose guns rose from 16 to 42. Automatic antiaircraft guns showed an increase from 151 to 203, and covered artillery positions rose from 39 to 67. There was a decrease in openly emplaced artillery, antitank and antiboat guns, and machine guns, but in the words of the Expeditionary Troops G-2, Colonel Edmond J. Buckley, the apparent reduction in observed machine guns could be offset by the heavy increase in field fortifications, including blockhouses and pillboxes. The blockhouses could contain fixed artillery, and, in numerous instances, their construction was such as to permit mobile artillery pieces to be wheeled into them. It also appeared likely that each pillbox was equipped with one or more machine guns, whose presence could not be ascertained by aerial observation.

Pre-landing reconnaissance had shown that the Japanese had established numerous

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antiboat gun positions, as well as coast defense guns. It was imperative that these guns be neutralized. Such neutralization, of course, depended upon the ability of the invasion force to detect targets and destroy them by naval gunfire and aerial attack prior to H-hour.33

Even though planners of the Iwo Jima invasion were generally correct with reference to the enemy’s intentions and capabilities, their intelligence estimate erred in two important respects. First among these was an underestimation of enemy strength on the island. Intelligence officers had estimated that the Iwo garrison numbered between 13,000 and 14,000 troops.34 Names and background of Japanese commanders in the Bonins were known, though the intelligence estimate mistakenly assumed that General Kuribayashi exercised overall command of the Volcano-Bonin Defense Sector from his 109th Division Headquarters on Chichi Jima, and that a Major General Osuka was in charge of the defense of Iwo Jima. Information on the Japanese naval guard and air base units on Iwo was lacking.

The second serious shortcoming of preinvasion intelligence was the mistaken assumption that the enemy defensive tactics to be expected on Iwo Jima would conform to tactics employed in earlier operations. In describing Japanese capabilities, the intelligence estimate voiced the following expectations:

The enemy may be prepared to attempt small local counterattacks prior to the establishment of our beachhead in order to annihilate our forces at the beach. His doctrine specifies that the enemy must not gain a foothold on shore and that in order to combat this all troops must be prepared to attack with the mission of splitting our forces and destroying them by local counterattacks.35

At the latest, the enemy could be expected to throw all available reserves against the beachhead prior to dawn on D plus 1.

In addition to their task of accumulating and analyzing all information available to them about the enemy’s strength, capabilities, and dispositions during the planning period, American planners were faced with the formidable problem of maintaining complete secrecy with reference to the movement of such a large force as was to take place in the Iwo Jima assault. This was not an easy undertaking in view of the tremendous size of the force assigned to capture and develop the island. Admiral Turner’s command alone consisted of 495 ships, including, among others, 4 command ships, 8 battleships, 12 aircraft carriers, 19 cruisers, 44 destroyers, 43 transports, 63 LSTs, and 31 LSMs. The addition of Task Force 58, together with supply and auxiliary ships, brought the invasion fleet to more than 800 vessels. The Marine assault troops numbered 70,647 officers and men.36 This force was further augmented by Marine and Army garrison units, as well as three Army amphibian truck companies in the assault phase, and Navy personnel assigned to shore duty, bringing the total of the expeditionary force to 111,308 men.37 If one further adds the crews of Turner’s

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ships and of Task Force 58, more than 250,000 men on the American side were involved in the Iwo operation.38

Intelligence officers had a few bad moments on 22 December 1944, when a Pearl Harbor newspaper printed two pictures of Iwo Jima under aerial attack. The pictures bore a startling resemblance to pictures and maps of “Island X,” which VAC had issued for training purposes. In order to prevent the Japanese from learning of the assembly and destination of the invasion force, General Schmidt recommended a counterintelligence diversion. Word was spread in the bars and hotels of Honolulu that the command would shortly depart for an attack on Formosa. Whether the diversion had any effect in deceiving the enemy could not be determined.39

A serious breach of security occurred on 14 February 1945, while the invasion convoy was en route to the objective. In the course of a radio transmission, someone in the vicinity of Saipan was overheard making the following statement:

We are going to Iwo Jima. It’s a Jap island not far from here. The B-29s bomb it from here every day. It’s about 600 miles from Japan. We’ll make it hot for them Japs when we get there. We’re leaving for there in the next day or so.40

Such a breach of security was more than enough to make experienced intelligence officers quake in their boots. The intelligence officer of Amphibious Group 2 reported the incident to VAC. There is no indication that this information ever reached the Japanese, though under different circumstances this compromise of vital information could have had disastrous consequences.

Logistics and Administration41

Another major responsibility accruing to the staff of the VAC was logistical planning, which had already begun even before VAC staff officers reached Pearl Harbor on 13 October. Special staffs of FMFPac conducted preliminary conferences and executed logistical planning for the assault on Iwo Jima. As in other areas, logistics required the harmonious teamwork of different levels of command, and between the armed services.

The Quartermaster, U.S. Army Forces, Pacific Ocean Areas, was responsible for supplying rations (Class I) to all personnel taking part in the operation, as well as clothing, special equipment, and supplies (Class II), and ammunition (Class V), for participating Army troops. Fuel and lubricants (Class III) were to be supplied

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by the Navy’s Service Force, Pacific. The Supply Service, FMFPac, was to furnish ammunition (Class V) and special supplies, and equipment (Class IV) for the Marines. The latter supplies were to be distributed initially by the 6th Base Depot in Hawaii and the 5th Field Depot on Guam.

Administrative planning, including service and support to the VAC Landing Force, was the responsibility of the G-4 Section, V Amphibious Corps. Prescribed levels for Class I supply were two days’ rations for the assault troops plus a 30-day backup supply. Water was to be carried in cans, drums, or other organizational equipment at the ratio of two gallons per man per day for five days.42 Class II and IV supplies were to be stockpiled for 30 days. Ammunition for ground forces (Class V) was to be provided in quantities of seven units of fire (U/F) for artillery, mortars, and antiaircraft guns, and five units of fire for all other types of weapons.43

Special preloads on LSTs were made to provide a balanced initial supply of rations, fuel, and ammunition for the assault troops. These supplies were loaded in LST tank decks and were designed to provide initial priority combat supplies close in to beaches on D-Day and D plus 1. A total of 38 LSTs were to be preloaded at Pearl Harbor, Hilo, and Guam prior to the embarkation of the assault units. In addition, 42 2½-ton Amphibian Trucks (DUKWs) were to be preloaded at Pearl Harbor with assorted small arms and mortar ammunition, rations, fuel, medical supplies, and flamethrower fuel. These vehicles were scheduled to provide an early replenishment supply on the beaches on D-Day.

Resupply plans and preparations were performed by the Marine Supply Service. Initial resupply ships were to be loaded at Oahu with 30 days Class I, II, and IV supplies and 15 days Class III supplies (except for aviation gasoline) for two reinforced Marine divisions and for all garrison troops estimated to be located on Iwo Jima at D plus 35. Class V was to be loaded in this shipment on board one ammunition ship at the rate of 9 U/F for one Marine division, 7 U/F for one 155-mm howitzer battalion, 8 U/F for one Army heavy antiaircraft battalion, 4 U/F for one Army light antiaircraft battalion, and 90 tons of engineer and Chemical Warfare Service demolitions.

The Commander, Forward Area, Central Pacific was instructed to hold available in the Marianas for shipment on call in an emergency, a stock of 30 days supplies of Classes I, II, III, and IV and two units of fire for one reinforced Marine division and one reinforced Army division. Supplies were to be provided by the Commanding General, Pacific Ocean Areas, the Commanding General, FMFPac, and ComServPac. ComAirPac was to maintain a 45-day stock of aviation supplies, except for Class V, in floating storage in the forward area for Navy and Marine aircraft employed in that area. Aviation supplies at Guam and on Roi-Namur were to be held available for emergency shipment. ComGenPOA was to maintain

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a 45-day stock of aviation supplies in floating storage in the forward area for Army aircraft. ComServPac was to provide the necessary storage if space and facilities assigned to ComGenPOA proved inadequate. ComServPac was to shift Service Squadron 10 to Ulithi to furnish support to fleet units and emergency supply for land-based forces. Elements of the above squadron were to be located in the Marshalls and Marianas for support of small task forces.

Pre-packaged supplies were stockpiled by the VAC Air Delivery Section on Saipan for emergency deliveries by air. If needed, the Commander, Expeditionary Troops, could draw from similar stockpiles in Hawaii and elsewhere in the Marianas. For the Iwo Jima operation, VAC organized the 8th Field Depot, commanded by Colonel Leland S. Swindler, The depot was designed to serve as the nucleus of the shore party organization; the depot commander had a dual designation as Shore Party Commander of the Landing Force, in which capacity he was responsible for coordinating the activities of the division shore parties.

Since Iwo Jima was not surrounded by reefs, all types of landing craft could proceed directly from the transport area to the beachhead without becoming involved in time-consuming transfer operations that had been characteristic of many previous landings in the Central Pacific. This circumstance led VAC to authorize subordinate units to mount up to 50 percent of their supplies on pallets.44

Planners of the Iwo operation were aware of the fact that the soft volcanic ash along the beaches, as well as the steep terraces en route inland, would impede the movement of wheeled vehicles. To insure a steady flow of supplies from the beaches inland, runner sleds were improvised that could be loaded with needed items and pulled inland by tracked vehicles. Another improvisation designed to overcome the soft sand or volcanic ash was the use of Marston matting at the beaches. Even though this material was originally used for the construction of airfield runways, it likewise could be employed to great advantage in bridging strips of sand along the beaches that would otherwise be impassable.

In addition to the large variety of supplies and equipment normally used for an amphibious operation, VAC employed two items for the first time. One was the two-wheeled Cleaver-Brooks 3½-ton amphibian trailer, the other the M-29C light cargo carrier, subsequently known as the “Weasel.” This boat-like, tracked vehicle resembled a miniature LVT without ramps. The amphibian trailers reached the three assault divisions during November and December 1944.45 The Weasels arrived in November and were subjected to extensive tests which revealed that the cargo carriers were capable of excellent performance under conditions anticipated at Iwo.

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Three Army and two Marine DUKW companies were assigned to VAC for the operation, as were the 31st and 133rd Naval Construction Battalions.46 In addition, a Marine engineer battalion, a topographic company, an Army bomb disposal company, and the 62nd Naval Construction Battalion were attached to VAC and placed under operational control of the Corps engineer. These units would be responsible for clearing minefields, bomb disposal, road construction and maintenance, water supply, and the restoration of airfields on Iwo Jima. Following the beach assault, and as soon as conditions permitted, the 62nd Naval Construction Battalion was to begin to ready Motoyama Airfield No. 1 for observation and fighter aircraft. Target date for completion of this assignment was D plus 7. The 31st Naval Construction Battalion was to restore Airfield No. 2 for use by the B-29 bombers. Making the latter field operational for this purpose involved not only restoration of facilities that were already in existence, but called for extension of existing runways to 7,000 feet to accommodate the giant aircraft. Airfield No. 2 was to become operational at D plus 10.47

In view of the size and scope of the impending operation, the handling and evacuation of casualties required special planning. Initially, it was assumed that seizure of the objective would require 14 days. It was estimated that five percent of the assault force would become casualties on each of the first and second days; three percent on the third and fourth days; and one and one-half percent on each of the remaining 10 days. It was further estimated that 20 percent of all casualties would be dead or missing.48

For the evacuation of casualties from Iwo Jima, two hospital ships, the Samaritan and the Solace were assigned, as well as the auxiliary hospital ship Pinckney, and LSTs 929, 930, 931, and 1033. These LSTs, especially equipped to handle casualties close to the beach, were to be stationed 2,000 yards offshore and serve as evacuation control centers. There, the casualties would be logged, given additional emergency treatment, and transferred to other ships for further care. One of the LSTs was equipped with a blood bank.

As in so many other instances of operations in the Pacific Theater, the adaptation of existing equipment to a new use was due to the efforts of one individual who not only conceived the idea but also had to sell it at the right time and place. In this instance the conversion of LSTs for the evacuation of casualties was the brainchild of Lieutenant Commander George J. Miller, Medical Corps, USNR, who prepared blueprints of the LSTs showing the plan of operating tables, beds, and other equipment. In December 1944 he presented his idea to several high ranking naval medical officers who initially vetoed it. In the end, the persistent lieutenant commander was able to sell the idea to an even higher ranking personage who immediately recognized the

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merit of the plan and gave his unqualified approval of it.49

In addition to the hospital ships and the specially converted LSTs, long range dispositions had to be made from Iwo Jima for the reception of casualties. In addition to the hospitals that were to be set up on the island itself, once the situation following the landings had stabilized to some extent, 5,000 beds were available in hospitals on Saipan and Guam. Air transportation of casualties was scheduled to begin as soon as airstrips were ready to accommodate transport planes.50

These preparations only give a bare outline of the time and effort required to bring logistics and administration into line with the operational planning. At least one account has briefly summed up the diverse items involved and the thought that had to be given to their transport and storage:–

It was necessary to think of everything—pencils, blood, toilet paper, ‘this item,’ said the orders, ‘will be stowed under tarpaulin at the rear of all landing vehicles to protect it from spray: matches, gasoline, socks, bullets, wooden crosses (preprinted), water, welding rods, garbage cans, splints, food, spark plugs, blankets, flares, dog food, maps, holy water, smoke pots, paint, shoelaces, fingerprint ink, batteries, rock-crushers, bulbs, cigars, asphalt machines, carbon paper. The Fifth Division alone carried 100 million cigarettes and enough food to feed Columbus, Ohio, for thirty days.

Ships began loading as early as November, every parcel stenciled, weighed, sized, and stowed in a particular spot. Marked photos showed where the cemetery would be located, orders specified the exact depth of burial and space between bodies (3 feet from centerline to centerline of body, fifty bodies to a row, 3 feet between rows.) The graves registration team would land on D-Day, equipped with its own bulldozers to bury the bodies exactly 6 feet deep. Then men would mound each grave with a special wooden form.51

Nor was the multiplicity of supplies all that the planners had to consider; there was one more commodity whose importance transcended all others. This was the flow of men towards the scene of action to replace those who would become casualties. During the last months of 1944, long before the first Marines were scheduled to hit the beaches of Iwo Jima, the complex machinery of administration was already set in motion when six replacement drafts embarked from the United States to join VAC. Each draft was composed of about 1,250 officers and men. Each of the three Marine divisions slated to participate in the operation received 2,500 replacements, some of whom were incorporated into the divisions before they left their staging areas. The bulk of the replacement units was kept intact; their personnel were assigned to shore parties, to be employed on the beaches until they were needed to replace combat losses.52

Launching an amphibious operation on the scale of the contemplated assault

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against Iwo Jima required far more than merely assembling men and matériel and shipping them to the objective. The real planning effort had only begun at the point when the objective had been decided upon and the means to seize it were being made available. The efforts of various arms and services had to be combined until the gigantic machine of war functioned as an instrument of precision. Each man, each weapon, each unit, every ship, tank, and airplane had a very definite part in the scheme of things. In this respect, an assembled invasion armada can be likened to an orchestra. The finest musicians, well skilled in their profession and equipped with the best instruments that money can buy, still must learn to work with one another. Few among the audience are aware of the tremendous effort that went into writing the score, the seemingly endless rehearsals, the continuous and often painful planning and rehoning that must take place before all meshes into an integrated whole.

It is no different with the orchestra of war. A plan is made, followed by the assembly of men and supplies. Only then can the vital and difficult process begin of forging the whole into an instrument of. such power and precision that it continues to function even in the face of the most adverse conditions that climate, weather, and enemy opposition can impose. When the curtain rises, the spectator is awed by the booming of the big naval guns, the columns of dirt and smoke rising over the objective from naval shells or aircraft dropping their lethal cargo, as rockets swoosh towards the target. Once this orchestra has begun to play, any flaw still remaining can be measured in the lives of assault troops who are separated from the enemy bullets and shells by no more than a few cubic feet of air, often protected only by the thickness of a uniform.

The forging of the precision instrument of war, under way months before Marines went ashore on Iwo, determined in large measure how many men of the landing force would go on to seize the objective and return home; the number whose fragile and mangled bodies would be carried off Iwo for salvage and repair; and those destined to remain on the island forever.