Japanese Defensive Preparations1
In early summer of 1944, as the tide of battle turned inexorably against the Japanese defenders of the southern Marianas, staff planners in Tokyo faced a thorny problem. Japan was losing the war it had started so confidently in December 1941. To the south and to the east, amphibious forces were steadily driving toward the core of the home island defenses. The steady attrition of air and undersea raiders had already cut off large numbers of garrison troops from effectual contact with Japan. A reasonable projection of Allied capabilities indicated that time for reinforcing the inner defenses was growing woefully short. For the next major Allied operation, aside from the inevitable return to the Philippines, Tokyo weighed probable targets of the South China Coast, Formosa, and the Ryukyus.
At Naha, headquarters of the newly formed Thirty-second Army, the choice of many potential objectives was narrowed to just one–Okinawa. Convinced that the main island of the Nansei Shoto would be invaded in the near future, staff officers hoped for enough time and men to make Okinawa a veritable fortress. Defensive planning was governed by bitter experience which had shown that “an army trained to attack on any and every occasion, irrespective of conditions, and with no calculation as to the real chances of success, could be beaten soundly.”2
A new defensive concept had been forced on the Japanese by the failure of this accepted doctrine in the Solomons and on New Guinea. In turn, the theory of “impregnable defenses” designed to stop landing forces at the beaches of the Gilberts, Marshalls, and Marianas collapsed before the power of the American air-sea-land assault team. The Japanese finally adopted a defensive system aimed at prolonging each individual action to the utmost and inflicting maximum casualties.3 In effect, the orders to the remaining island garrisons were to dig in, go underground, prepare for a protracted defense, and together with Japanese naval and air forces bleed Allied striking power to an
anemic standstill. For the Thirty-second Army the new concept was reflected in its battle slogans:
One Boat for One Ship
One Man for Ten of the Enemy or One Tank4
The Thirty-Second Army
Lieutenant General Mitsuru Ushijima succeeded to the command of the Thirty-second Army in August 1944.5 Exercising his recognized talent for choosing capable subordinates, he selected one of the ablest officers of the Japanese Army, Major General Isamu Cho, as his chief of staff. Cho, in turn, hand-picked from the “bright young men” of Imperial Headquarters a smoothly functioning staff exceptional for its alert and progressive attitude.
This command team, Ushijima and Cho, formed an effective combination in the tradition of Germany’s Hindenburg and Ludendorf in World War I.6 Ushijima, a senior officer slated for promotion to general in August 1945, was reputedly a quiet, competent man capable of inspiring great confidence and respect in his subordinates. Both he and Cho were veterans of the Burma campaigns early in the war, Ushijima as an infantry group commander and Cho as assistant chief of staff of the Southern Army. Prior to assuming command of the Thirty-second Army, General Ushijima served as Commandant of the Japanese Military Academy. During the same period, Cho was assigned to the General Military Affairs Bureau of the War Department. General Cho, an extremely aggressive man with an Army-wide reputation as a strict disciplinarian, was the firebrand of the Okinawan defense. According to Japanese sources, he was relatively young for his rank and destined for high position in the service.7 With his fiery faculties counterbalanced by Ushijima’s soft-spoken demeanor, Cho effectively managed the strengthening of the Ryukyuan defenses.
Although units of division and brigade strength were added to garrisons on the other islands of the Nansei Shoto, notably Miyako Jima, the major reinforcement was made on Okinawa. Here the Americans were expected to land. To a large extent, in keeping with their flexible combat organization, the Japanese attempted to tailor the Thirty-second Army for the coming showdown battle. Many independent artillery, mortar, antiaircraft artillery (AAA), antitank (AT), and machinegun units were assigned to the army to augment the firepower of its basic infantry strength.
Between June and August 1944, the major reinforcing units arrived from their former posts in China, Manchuria, and Japan. The 9th Infantry Division, first to arrive, was a veteran organization with battle honors dating from the Russo-Japanese War (1904-5). Considered by the Japanese to be the crack unit of the defensive force, it came directly from Manchuria. Fortunately for the Americans, however, the 9th Division was not destined to participate in the coming battle. The division left Okinawa for the Philippines in December by way of Formosa. MacArthur’s landing on Luzon in January caught the 9th still on Formosa, where it stayed, shepherded by Allied submarines and planes, until the end of the war.8
In late June, about 600 men, survivors of the 44th Independent Mixed Brigade (IMB) landed on Okinawa. The brigade, later to become the headache of Tenth Army order of battle interpreters, had been raised at Kumamoto,
Kyushu in early June. Originally composed of the 1st and 2d Infantry Units (both approximately regimental size) with a combined complement of around 6,000, its organization and strength varied considerably over the course of the following months. While en route to Okinawa on 23 June 1944, its convoy was attacked by American submarines, and the Toyama Maru was sent to the bottom with more than 5,000 men. Replacements for one of the infantry units, the 2d,were raised in late summer on Kyushu and Okinawa.9 The 1st Infantry Unit, however, existed merely as a headquarters and was never rebuilt. Instead, another newly-raised unit, the 15th Independent Mixed Regiment (IMR), was flown directly from Tokyo to Okinawa, and added to the 44th IMB in July, bringing its strength up to about 5,000 men. (See Chart 3)
The 24th Infantry Division, organized in December 1939 in Toan, Manchuria as part of theKwantung Army, was the next major unit to arrive on Okinawa (July). Although this division, commanded by Lieutenant General Tatsumi Amamiya, was not battle-tested, it was well-trained and considered combat ready. The 24th, a triangular division, had been stripped of its infantry group headquarters, one battalion from each of its regiments, an artillery battalion, and an engineer company to help form various reinforcing expeditionary units sent from Manchuria to the Central Pacific in early 1944. For several months after their arrival, the 24th’s infantry regiments, the 22d, 32d, and 89th Infantry, operated as two battalion units. In October over 1,200 Okinawan conscripts were added to the division for training and eventual absorption, and in January 1945 a general reorganization brought the unit very near its original strength. As the largest tactical unit in the Thirty-second Army on Okinawa, the 24th Division had over 14,000 Japanese troops and Okinawan conscripts assigned to its infantry, artillery, reconnaissance, engineer, and transport regiments, and to divisional troops. (See Chart 4)
The last major unit assigned to the Thirty-second Army, the 62d Infantry Division, commanded by Lieutenant General Takeo Fujioka, arrived on Okinawa in August. The division had been activated in June 1943 in Shansi Province, China. Its internal organization, which varied considerably from that of the 24th Division, was typical of similar units in the Chinese Expeditionary Army. A square division whose brigades both had served in China as independent commands since 1938, the 62d fought as a unit in the April-June 1944 campaigns in northern Honan Province. Organic to each brigade were four independent infantry battalions (IIB); the 63d Brigade had the 11th, 12th, 13th, and 14th IIB’s, and the 64th Brigade had the 15th, 21st, 22d,and 23d IIB’s. In January 1945 two additional independent infantry battalions sent as reinforcements to Okinawa were attached to the division, which assigned the 272d IIB to the64th Brigade and the 273d IIB to the 63d Brigade. The division had no organic artillery and few other supporting units, and its strength, even with the addition of the 272d and 273d IIB’s,amounted to less than 12,000 men, almost all infantry. (See Chart 5)
Within the infantry components of the three major fighting organizations on Okinawa, there was some variance in strength. The 44th IMB’s 2d Infantry Unit and 15th IMR each had three rifle battalions, an antitank company (4 37mm or 47mm AT guns), and a regimental gun company (4 75mm guns). Each battalion had three rifle companies, a machine-gun company, and an infantry gun unit (2 70mm howitzers) with a total strength of roughly 700 men. In the regiments of the 24th Division, the organization was similar except that one battalion in each regiment had a mortar platoon (4 81mm mortars) instead of the usual 70mm howitzers.
The 62d Division’s organic battalions were the strongest infantry units on the island, each mustering 1,200 men in five rifle companies, a machine-gun company, and an infantry gun company with two 75mm guns and two 70mm howitzers. Available evidence indicates the
THIRTY-SECOND ARMY OFFICERS sit for a formal portrait in February 1945. Numbers identify: (1) Rear Admiral Minoru Ota, Commander, Naval Base Force; (2) Lieutenant General Mitsuru Ushijima, Commanding General, Thirty-second Army; (3) Lieutenant General Isamu Cho, Army C/S; (4) Colonel Hitoshi Kanayama, Commanding 89th Regiment; (5) Colonel Kiuji Hongo, Commanding 32d Regiment; (6) Colonel Hiromichi Yahara, Army Senior Staff Officer. (Photograph courtesy of OCMH, DA)
attached 272d and 273d IIB’s, with a reported strength of 700 men each, had one or two less rifle companies.
Because it was expected that the battle for Okinawa would develop into a relatively static position defense,Thirty-second Army was not assigned any strong armored force. The sole tank unit on the island, the 27th Tank Regiment, was organized in Manchuria in April 1944 from elements of the 2d Armored Division and reached Okinawa in July. The regiment was in effect an armored task force with a strength of 750 men organized into one light and one medium tank company, a tractor-drawn artillery battery, an infantry company, a maintenance company, and an engineer platoon.10 Major armament of the regiment included 14 medium and 13 light tanks, four 75mm guns, two 47mm AT guns, and ten machine guns.
All artillery on Okinawa, with the exception of the 24th Division’s organic 42d Field Artillery Regiment, was under control of Major General Kosuke Wada’s 5th Artillery Command. In addition to the relatively weak 7th Heavy Artillery Regiment (the former Nakagusuku Wan Fortress Artillery Unit), General Wada’s command included two medium regiments,
a heavy battalion, and the artillery units of the 44th IMB and 27th Tank Regiment. The combat-tested 1st Medium Artillery, which came from Manchuria in July, was a two-battalion regiment whose 1st Battalion was sent on to Miyako Jima.11 The 23d Medium Artillery Regiment, which arrived in October, had been activated in 1941 and stationed since then in Japan. Together the two medium regiments mustered 2,000 troops to man 36 150mm howitzers. The 100th Independent Heavy Artillery Battalion had been formed in the fall of 1943 and brought its 500 men and eight 150mm guns directly from Japan to Okinawa in July 1944.
An unusual unit, of a type first encountered by Marines on Iwo Jima12 also operated under the5th Artillery Command. This 1st Independent Artillery Mortar Regiment (or rather three of its batteries, since the other three had been sent from Manchuria to Burma in mid-1942) added 24 320mm spigot mortars to the Thirty-second Army’s supporting fires.13 In addition to these awesome weapons, whose 675-pound shells were dubbed “flying ashcans” by Americans, 96 81mm mortars in two light mortar battalions were available to Thirty-second Army. Although the 81mm mortar units were nominally under 5th Artillery Command, in actual practice they were assigned close support missions with the various infantry units and usually operated under sector defense commanders.
Besides the mortars and artillery gathered loosely under the 5th Artillery Command’s aegis, many antiaircraft, antitank, and automatic weapons units were directly attached to the infantry during most of the campaign. Three independent AAA, three field AAA, and three machine cannon battalions performed a double role of air and ground defense with 72 75mm guns and 54 20mm machine cannon. Three independent AT battalions and one independent company, all newly equipped with the effective 47mm gun, added 48 more high-velocity, flat trajectory weapons to the defense. Finally, rounding out the roster of nominal ground combat units, four independent machine-gun battalions with 96 heavy machine guns were closely integrated into infantry defensive positions.
In addition to the aforementioned line troops, the Thirty-second Army had many diversified supporting elements. Included in this number were thousands of potential infantry replacements of varying caliber, ranging from good in the two shipping engineer regiments to poor, at best, in the various small service units. One of the largest groupings of these units, numbering some 7,000 men, was under the 19th Air Sector Command Headquarters and consisted for the most part of airfield maintenance and construction troops stationed at the airstrips at Yontan and Kadena and on Ie Shima.
One category of Thirty-second Army troops, first encountered in the Philippines, deserves special mention: the sea raiding units.14 Disguised in Japanese records by a variety of cover names, these super-secret organizations were designed to destroy amphibious invasion fleets with explosive-laden suicide boats. In the Okinawa Gunto, there was a total of seven sea raiding squadrons, three stationed in Kerama Retto, each with a strength of about 100 hand-picked men and 100 boats.15 Supporting each squadron was a base battalion with a strength of 900 men whose duties included the construction and protection of the raiding base and the maintenance of the boats.
General Ushijima not only controlled all the Army air and ground units on the island, but was to assume command of the naval units on the island once ground combat was joined. Most of the 3,500 Japanese navy men and 6,000-7,000 civilian employees belonged to sub-units
of the Okinawa Base Force under Rear Admiral Minoru Ota, an officer who had had considerable experience with Special Naval Landing Force units.16 With the exception of a naval 81mm mortar battery (18 mortars), none of Admiral Ota’s units were trained for ground combat prior to arrival on Okinawa. A small number of naval officers and enlisted men and most of the civilians were formed into maintenance, supply, and construction units for the large airfield on Oroku Peninsula and the harbor installations at Naha. At Unten-Ko on Motobu Peninsula, a torpedo boat squadron and a midget submarine unit were stationed. The major portion of the regular naval troops were formed into antiaircraft and coast defense batteries. Organized into four battery groups–emplaced mainly in the Naha-Oroku-Tomigusuku area–the AAA units manned 20 120mm guns, 77 25mm machine cannon, and 60 13mm machine guns. The 15 coast defense batteries were placed at strategic locations on the island’s coast line, where their 16cm and 12cm rifles were under local Army sector commanders.
An important manpower augmentation of the Japanese Army was encountered for the first time on Okinawa. In June of 1944, faced with a steadily worsening military situation, Imperial Headquarters authorized the War Ministry to organize a Home Guard. The Boeitai, as the guard was called, consisted initially of all reservists in the 20-40 age group, including those who under the Japanese conscription system normally were not liable for regular service.17 Local Army commanders, such as General Ushijima, assumed control of the Boeitai conscription set-up in their areas. These generals had wide latitude in details of conscription, organization, and utilization of the home guards. On Okinawa, almost as soon as the authorization was received, the Thirty-second Army began drafting men to help build up the island’s defenses. These home guardsmen augmented the regular active service conscriptees, who may have numbered as many as 7,000. Exactly how many Okinawans eventually served in defense of their island is not known, but conservative estimates place the figure close to 20,000.
The Boeitai were a valuable addition to Thirty-second Army forces, although their capabilities as combat troops were slight. The majority bolstered regular units as labor details and rear echelon increments for service troops. Their drills, picks, and shovels steadily digging into the Okinawan hillsides over a period of almost nine months contributed substantially toward prolonging the battle for the island. Defenses that they helped dig were manned by combat troops they relieved from rear area duties. This additional manpower enabled the Thirty-second Army to stand off the American assault forces for three bitter and bloody months.
Strengthening the Defenses
“It became axiomatic in the Pacific War that the Japanese would dig and construct in a way and to an extent that an American soldier has never been known to do.”18 The pattern of organization of the ground on Okinawa paralleled that which assault forces found on Biak and Peleliu in late 1944 and on Iwo Jima in February 1945.19 The most favorable defensive terrain was occupied and honeycombed with mutually supporting gun positions and protected connecting tunnels. Natural and manmade barriers were effectively incorporated into the defensive system in order to channelize an
attack into prepared fire lanes and pre-registered impact areas.
Soon after General Ushijima took over the Thirty-second Army, its headquarters was split into two groups. The operations staff moved to Shuri, while a “rear headquarters” composed of the ordnance, veterinary, judicial, intendence,20 and the greater part of the medical staff set up near Tsukasan. The separation of functions enabled the operations staff, under Colonel Hiromichi Yahara, to concentrate on developing a tactical scheme for effective utilization of Thirty-second Army manpower and firepower.
As each combat element arrived on Okinawa it was assigned a sector to develop and defend. By August 1944, the 44th IMB had occupied its area, Kunigami Gun, and was responsible for all of the island north of Ishikawa Isthmus, including Ie Shima and its airfields. The 24th Division had begun to construct field fortifications around Yontan and Kadena airfields in an area bounded by Ishikawa Isthmus in the north and a line from Sunabe to Ozato in the south. Below the 24th’s defensive zone the 62d Division was assiduously digging into the ridges, hillsides, and ravines north of Shuri. The 9th Division assumed responsibility for the entire southern portion of Okinawa below Shuri.
In late November, when orders were received to ship the 9th Division to the Philippines, the 24th Divisionbegan moving south to partially replace it. The 44th IMB, leaving two reinforced battalions of the 2d Infantry Unit behind on Ie Shima and Motobu Peninsula, took over an area stretching from Kadena airfield to Chatan. The sudden withdrawal of 14,000 combat troops also necessitated a readjustment in 62d Division lines. The northern divisional boundary dropped to Chatan-Futema and in the south the zone of responsibility was vastly increased to include Naha, Shuri, Yonabaru, and the entire Chinen Peninsula.
Throughout this period of troop movement, extensive fortification activities continued. As
each unit occupied its new area, it added to existing installations. The Japanese planners meanwhile considered four possible defensive schemes, all aimed at denying the invasion force “the use of the island for as long a period as possible and [causing it] the greatest casualties.”21Japanese sources list the following alternatives:
To defend, from extensive underground positions, the Shimajiri sector, the main zone of defenses being north of Naha, Shuri, and Yonabaru. Landings north of these defenses were not to be opposed; landings south of the line would be met at the beaches. Since it was impossible to defend Kadena Airfield [with available troops], 15cm guns were to be emplaced so as to bring fire on the airfield and deny the invaders its use.
To defend from prepared positions the central portion of the island, including the Kadena and Yontan airfields.
To dispose one division around the Kadena area, one division in the southern end of the island, and one brigade between the two divisions. To meet the enemy wherever he lands and attempt to annihilate him on the beaches.
To defend the northern part of the island, with Army Headquarters at Nago, and the main line of defense based on Hill 220, northeast of Yontan Airfield.22
Eventually, after due consideration of the forces available, Plan I was selected as having the best chance of accomplishing the army’s mission. Plan IV was rejected mainly because it conceded immediately the loss of the militarily important south. Similarly, Plan III, which attempted to defend these important objectives, was abandoned because it overextended Thirty-second Armytroops. Plan II, appearing potentially the most dangerous to American staff officers, was given up reluctantly by the Japanese. Had it been followed by a Japanese army relatively untrained in fighting delaying actions23 and subject to fragmentation by separate American landings, Ushijima considered that he might not be able to prolong the battle and inflict satisfactory casualties.
Under Plan I the rugged terrain surrounding Shuri was selected and developed as the main Japanese battle position with the strongest defenses oriented north toward the Hagushi beaches. To planning teams on both sides the Hagushi area seemed the obvious primary target. In addition, Japanese officers, “handicapped by their lack of ability to make an American logistics estimate for a landing operation,”24 believed there would be another assault across the Minatoga beaches of southern Okinawa. The terrain inland from these beaches along the southeast coast of the Chinen Peninsula was so favorable to the defenders that they expected to exact a bloody price for a beachhead. Thanks to this flattering appraisal of American capabilities, a substantial portion of the Thirty-second Army’s infantry and artillery strength which could have reinforced the Shuri bastion was to be held out of action during the first weeks of Tenth Army operations ashore.25
In January 1945, General Cho flew to Tokyo for a final round of conferences regarding the defense of Okinawa. Here he was told that sea and air suicide attacks would carry the entire burden of destroying American invasion shipping; Thirty-second Army artillery and coast-defense guns were to hold their fire. While great confidence was placed in the effectiveness of the suicide units, there was another telling reason for the “deathly stillness.” As an army battle instruction explained, “The most effective and certain way of ascertaining the existence and organization of our firepower system is to have us open fire prematurely on
44th Independent Mixed Brigade
a powerful force in a situation where it can maneuver.”26
A healthy respect for the American air-NGF team resulted in the adoption of “the basic principle” of allowing “the enemy to land in full.”27 The Japanese command thought that the landing force would be effectively deprived of a large part of its supporting firepower once it became embroiled in the tangled skein of the island’s defenses.
Either at Cho’s January Tokyo conference or immediately thereafter, it became painfully apparent that the expected replacements for the 9th Division would not be forthcoming in time.28 It now was necessary to find additional combat troops within the ranks of the Thirty-second Army. A drastic reorganization of army service troops took place in February and March 1945.
Reinforcing the Army
On 1 January 1945, Thirty-second Army distributed to all units an order for total garrison mobilization. Under its terms all male islanders between 17 and 45, in good health, and possessed of “high morale” were adjudged “fit for direct battle.” By the end of April mobilization was expected to be complete. Those “incapable of participation in battle”–most of the women, the aged, and children–were directed to move to northern Okinawa, thus clearing the projected battle zone.29 Many of the rural people, however, managed to escape evacuation and stuck stubbornly to the area of their farmsteads.
The rate of induction of the Okinawans accelerated in the early months of 1945, adding to
the pool of labor available for defensive construction. In February over 39,000 natives were temporarily assigned to Thirty-second Army units, divided into categories of Main Labor (22,383), Auxiliary Labor (14,415), and Student Labor (2,944).30 In all probability, only a portion of this number actually entered military service, but the figure serves to confirm American estimates of 20,000 Boeitai who actually served in the Thirty-second Army. While comparatively few Home Guardsmen were integrated into front line units, their contribution to defensive preparations was substantial.
In addition to the Boeitai, the Japanese made a special effort to use the indoctrinated, politically reliable students of high school level in the Naha-Shuri area. In January, 750 of these young men were organized into Blood-and-Iron-for-the-Emperor-Duty-Units. A specialist from Japan trained them in the techniques of infiltration and guerrilla warfare. An additional 600 students were assigned to various headquarters as messengers, orderlies, and communications assistants. Before the campaign on Okinawa ended, many students, with a fanaticism comparable to that of the Hitler Youth Organizations, perished in attempts to destroy American tanks and rear area installations.
Although successive drafts of Okinawans were added to the Thirty-second Army, they did not compensate for the loss of the infantry strength of the 9th Division. It became imperative that additional riflemen be found within the army to reinforce combat units of the divisions and 44th IMB. In February the process of converting service troops to infantry began.
The seven sea raiding base battalions were the first elements affected by the reorganization. Between 13 and 20 February, these units, renamed the 1st, 2d, 3d, 26th, 27th, 28th, and 29th Independent Battalions, were removed from control of the sea raiding base headquarters and assigned to the major combatant units. Each battalion consisted of three companies, some reinforced by Boeitai, which varied in strength from 150-300 men.31 A maintenance
24th Infantry Division
62d Infantry Division
company remained under command of each sea raiding squadron to assist it in carrying out its suicide boat mission. The new independent battalions were poorly trained and equipped by comparison with regular infantry units, but their 4,500-5,000 men fed into existing combat formations provided an important source of Japanese strength during battle.
In March 1945 the Army forces defending Okinawa underwent their final reorganization to meet the imminent American assault. The Thirty-second Army published an order on 21 March directing “the various shipping, air, and rear echelon forces [to] set up organizations and dispositions for land combat.”32 In addition to their normally assigned functions, units named in the order were to give priority to construction of positions and training for infantry action. By 10 April the changeover was to be completed.
On paper the new organizations, two brigades and a regiment, looked impressive; in actuality, the lightly equipped, untrained service troops were of tactical value only as combat replacements. The 1st Specially Established Regiment, formed from units under 19th Air Sector Command Headquarters, was to defend, under 62d Division control, the area of Kadena and Yontan airfields. The 1st Specially Established Brigade, three regiments of Thirty-second Army transport, ordnance, construction, and supply troops under the 49th Line of Communication Sector Headquarters, assumed support positions in the Naha-Yonabaru valley. The 2d Specially Established Brigade, three regiments composed mostly of shipping, sea transport, and engineer personnel under the 11th Shipping Group Headquarters, deployed in the 24th Division area to back up that unit in its defense of southernmost Okinawa. Thus, the 21 March order effected general mobilization for combat since Thirty-second Army further directed that all “Army rear echelon agencies not included in this order and their personnel will be under command of the front line unit in the vicinity where their duties are carried on, and will reinforce it in combat.”33
By the time of the American landings in Kerama Retto (26 March), most of the Japanese Army ground and air troops on Okinawa had been integrated into the defensive organization. About the same time, the naval troops and civilian auxiliaries under Okinawa Base Force were ordered to organize for land combat. These units varied greatly in size, the only standard seeming to be that naval lieutenants should command those organizations
named battalions and lieutenants (junior grade) should lead those named companies. Like the specially established units of the Army, the land combat organization of the Navy suffered from a lack of individual weapons. The only units adequately equipped were the 81mm mortar battery and two independent machine-gun battalions formed from the 13mm and 25mm AAA batteries. The addition of almost 10,000 naval troops to approximately 40,000 service troops and Boeitaidoubled the potential combat strength of the Thirty-second Army.34
While the Okinawan populace and the ranks of the Thirty-second Army were being combed for combat replacements, the main defensive sector was readied for battle. The twisted, confused character of the terrain surrounding Shuri featured escarpments, steep slopes, and narrow ravines that showed no discernible pattern, making it “ideal for an enemy whose chief reliance was on large numbers of short range weapons, and whose propensities for digging enabled him to make each irregularity of the terrain into a fortress.”35 Routes of approach into the battle area were mined and swept by the fire of AT guns. Automatic weapons, mortars, and artillery were zeroed in on all possible attack objectives, especially hill crests and reverse slopes, so that even if the Americans did capture a commanding height they would be subjected to intense pre-registered destructive fires. Covered passageways connected many of the enemy positions, and natural and man-made caves afforded protection to troops, weapons, and supplies. The Japanese were determined to defend Shuri to the last man, capitalizing on every advantage given them by the wildly irregular terrain.
During February the final enemy deployment for battle took place. Following the accepted plan, Kadena airfield and the rest of the area between the Hagushi beaches and Chimu Wan were left to the doubtful protection of 19th Air Sector Command units. The main battle force withdrew below an outpost zone north of Futema. (See Map 8)
Because of their belief that American troops would land on the Minatoga beaches, the Japanese positioned much of their reserve strength to oppose that landing. The 44th IMB took over the defense of the rugged hills of the Chinen Peninsula which commanded both the supposed landing area and the reaches of Nakagusuku Wan. The 24th Division continued to occupy the high ground inland from the southern coast, strengthening the positions begun by the 9th Division. On Oroku Peninsula, the Naval Base Force prepared to fight “the Navy Way,” meeting the enemy at the beaches in a manner similar to that used at Tarawa.36 The most significant realignment of forces, though, was the assignment of a major portion of the units under the 5th Artillery Command to the southern sector to back up the Minatoga beach defenses.
The battle-tested 62d Division, considered the most valuable combat unit on the island, was confirmed in its role as guardian of the heart of Okinawa’s defenses. The Shuri bastion assumed the form of a series of concentric rings, each bristling with dug-in, mutually supporting weapons. If the Americans landed at Hagushi and Minatoga, plans called for making a fighting withdrawal to these prepared positions, extracting a terrific toll in lives for every yard of advance.
Isolated in the north, the Kunigami Detachment, under Colonel Takehiko Udo (Commanding Officer, 2d Infantry Unit), was charged with the defense of Motobu Peninsula and Ie Shima. Colonel Udo expected that Ie Shima would be attacked from the sea and that Motobu, in turn, would receive an amphibious assault from the direction of that island. In so far as possible then, he emplaced his few artillery pieces to make the two positions mutually supporting. On 11 March, when Thirty-second Army ordered the destruction of the airfields of Ie Shima, the forlorn hope under Udo’s command was ready for its part in the war of attrition.
Shortly before 1 April 1945, belated orders called for the destruction of airfields at Yontan, Kadena, and Oroku. By that time, carrier raids, Japanese suicide sorties, and finally the fires of Task Force 54 had combined to destroy most of the 30-31 planes that remained on Okinawa at the beginning of March.37 Because the island was used mainly as a servicing and maintenance stop on the air route to Formosa and the Philippines, organic air power was never a significant factor in Thirty-second Army defensive plans.
The army did count, however, on the combat power of its own sea forces. It was expected that the sea raiding squadrons at Kerama Retto and those positioned along the coast of Okinawa would “blast to pieces the enemy transport groups with a whirlwind attack in the vicinity of their anchorages.”38 The Navy’s midget submarines and motor torpedo boats stationed at Unten-Ko were unable to assist this grand scheme. By L-Day carrier airstrikes had knocked out all the submarines, and the torpedo boats had been destroyed or scattered in an abortive attack on the destroyer Tolman of TF 52.39
As both sides in the impending struggle made their final preparations, the Thirty-second
Sketch Map of
Japanese Defensive Positions
1 April 1945
Army issued a battle warning to its troops. The news that Admirals King and Nimitz had met in Washington in early March was translated by the Japanese into a general alert “for the end of March and early April” based on a statistical estimate “that new operations occur from 20 days to one month after conferences on strategy are held.”40 The validity of this estimate was confirmed three days after the warning was issued, when repeated sightings of Allied ships and submarines enabled Japanese intelligence officers to predict that the target was “Formosa or the Nansei Shoto, especially Okinawa.”41
1. Unless otherwise noted the material in this chapter is derived from Okinawa Operations Record; IntelMono; Tenth Army G-2 POW Interrogation Summaries Nos 1-19, July-August 1945, hereinafter cited as POW InterSum; Tenth Army G-2 Interrogation Rpt No 27, Akira Shimada (Secretary to LtGen Cho), 24Jul45, hereinafter cited as Shimada Interrogation; Tenth Army G-2 Interrogation Report No 28, Col Hiromichi Yahara (Senior Staff Officer, Thirty-second Army), 6Aug45, hereinafter cited as Yahara Interrogation.
2. IntelMono, Part I, Sect A, 3.
3. USSBS(Pac), NavAnalysis Div, Interrogations of Japanese Officials, 2 vols (Washington, 1946), Interrogation No 447, LtGen Torashira Kawabe, II, 426-427. This publication hereinafter referred to as USSBS Interrogation with interrogation number and name.
4. CinCPac-CINCPOA Bull 122-45, Translations and Interrogations No 30, 1Jun45, 32d ArmyBattle Instructions, 15Feb45.
5. The original commander of the Thirty-second Army, LtGen Hasao Watanabe, had been forced to retire due to chronic illness. His chief of staff, MajGen Kiyom Kitagawa, was replaced shortly thereafter by the new army commander.
6. This famous relationship has been described by MajGen Hunter Liggett, commander of the First U.S. Army, A.E.F. “[Hindenburg] was the army’s chief, [Ludendorf], his executive officer, but Ludendorf was the younger man, the greater organizer, more brilliant strategist, more resourceful mind; he was the greater in every respect but one–character.” MajGen H. Liggett,A.E.F.: Ten Years Ago in France, (New York, 1928), 33.
7. On 1Mar45, at the age of 51, Cho was promoted to lieutenant general.
8. MIS, WD, Order of Battle for the Japanese Armed Forces, 1Mar45, 32.
9. The 2d InfUnit, although it was rebuilt and reorganized, never regained much of the organic equipment lost on the Toyama Maru. As a result it gained the nickname of Bimbo Tai (Have-Nothing Unit) among the Japanese troops.
10. Originally the 27th TkRegt had two medium tank companies, but one was sent to the garrison of Miyako Jima.
11. The 1st MedArtyRegt (also called the 1st FldHvyArtyRegt) was one of the original units to land at Lingayen Gulf in December 1941 and it participated in the struggle for Bataan. See L. Morton, The Fall of the Philippines, U.S. Army in World War II, (Washington, 1953), passim.
13. Each battery had in addition two 90mm mortars and two light machine guns.
15. These men, mostly middle school graduates, were of a uniformly high caliber and considered officer candidate material. When one failed to return from a suicide mission, therefore being presumably successful, he was reportedly given a posthumous promotion to second lieutenant.
16. The Okinawa Base Force was activated 15Apr44 with RAdm Teizo Nippa in command. In January 1945, Adm Ota, who had commanded a SNLF battalion in the Shanghai Incident, the Munda SNLF, and the Sasebo Naval Barracks, relieved him.
17. Nominally, Japanese conscription classes included seven categories of men in the 20-40 age group with the distinctions based on physical characteristics. Except for men considered unfit for even limited service (Class D) and those suffering temporary ailments (Class F), all eligible males were assigned either to active service or to units with varying liabilities for reserve training. Those men in the 2d National Army were generally considered, because of their poor physical condition or lack of height (between 4′ 9″ and 4′ 11″), to be available only for emergency call. WD, Handbook on Japanese Military Forces, 1Oct44, 2-4.
18. IntelMono, Part I, Sect A, 5.
20. The Intendence Service, which had no exact U.S. military equivalent, controlled clothing, rations, forage, contracts, pay, and the upkeep of Army buildings. In effect, it combined the functions of the U.S. Army Quartermaster Corps and Finance Department. WD, Handbook on Japanese Military Forces, 1Oct44, 50.
21. Shimada Interrogation.
22. IntelMono, Part I, Sect A, 1-2.
23. In a delaying action a small, highly mobile covering force with relatively few troops employs elusive, fast-moving tactics to force the enemy into premature deployments. It avoids becoming heavily engaged before withdrawing to previously selected positions to the flank or rear since to do so would mean its destruction while unsupported by rearward defensive positions.
24. IntelMono, Part I, Sect A, 3.
25. In the Thirty-second Army staff there was sharp disagreement as to the probability of this additional landing. Col Yahara, senior staff officer, insisted that a diversionary landing, possibly the principal one, would be made in the Minatoga region. Maj Yakamaru, the intelligence officer, held that the only American landing would be in the Hagushi area. Prestige and seniority won the argument. “Yakamaru, bitterly disappointed at the final decision, went off the next few days to inundate his sorrows in prolonged draughts of expensive sake.” Shimada Interrogation.
26. CinCPac-CinCPOA Bull 122-45, Translations and Interrogations No 30, 1Jun45, 32d ArmyBattle Instructions No 8, 8Mar45, 7.
28. On 23Jan45, Thirty-second Army received an Imperial Headquarters order to the effect that the 85th Division from Honshu would be sent to Okinawa. By nightfall the order was cancelled and the last hope of substantial reinforcement lost.
29. CICAS Trans No. 83, Standards for the Establishment of Nansei Shoto Garrison Plans, 1Jan45. “In June of 1944 the governor of Okinawa Ken [Prefecture] ‘suggested’ that all women and children go to Kyushu or to northern Okinawa since they would be in the way if Okinawa became a battleground. Accordingly, from June to November about 50,000 . . . went to Kumamoto Ken in Kyushu. Passage was free, but they were expected to work in factories after their arrival.” 1st MarDiv G-2 PrdRpt No 79, 19Jun45, Preliminary Interrogation Rpt No 110.
30. CinCPac-CinCPOA Bull 161-45, Translations and Interrogations No 34, 27Jun45, 32d Army–Assignment of Conscript Labor, February 1945.
31. Although total strength varied, the organization of the 1st IndBn might be considered typical: a headquarters of 50 men and three companies of 150-180 men, each man armed with a rifle and five to ten grenades, with the companies having four light machine guns and two grenade dischargers apiece. Only one unit, the 1,100-man 29th IndBn, formed a machine-gun company, but its weapons (three heavy and six light machine guns) were redistributed to the rifle companies prior to entering combat.
32. IntelMono, Part I, Sect B, 14.
33. Ibid., 15.
35. IntelMono, Part I, Sect A, 4.
36. Although the Base Force was under command of the Thirty-second Army and Adm Ota adopted a policy of full cooperation, certain of his staff were dissatisfied with local Army procedure and nurtured the spirit of fierce inter-service rivalry that hampered many Japanese Pacific operations. POW InterSum No 16, Naval Units on Okinawa, 28Jul45.
37. The plane strength was compiled after an examination of unit reports contained in POW InterSum No 16, Naval Units on Okinawa, 28Jul45; POW InterSum No 19, Air-Ground Units, 25Jul45.
38. CICAS Trans No 231, 32d Army OpOrd A #115, 23Mar45.
39. Some POW’s claimed that these boats were enroute to Sakishima Gunto and a fight “was not especially sought after.” POW InterSum No 16, Naval Units on Okinawa, 28Jul45. TF 52’s operation chronology for 28Mar45 notes, “From 0100 (I) to 0220 (I) Tolman on patrol south of Zampa-Misaki was under attack by 8 MTB. Two MTB destroyed, 2 probably destroyed, remainder driven off, Tolman undamaged.” CTF 52 AR, Chap III, 9.
40. CinCPac-CinCPOA Bull 140-45, Translations and Interrogations No 31, 7Jun45, 32d ArmyEstimate of the Situation, 20Mar45.
41. Ibid., 62d Div IntelRpt on Findings Since the 20 March Rpt, 23Mar45.