The ease with which American forces landed and established themselves on Okinawa gave rise to widespread speculation as to the whereabouts of the Japanese Army. The most optimistic view was that the enemy had been strategically outguessed and had prepared for the Americans at some other island, such as Formosa. Or, if Okinawa was not to be another Kiska, there was the possibility that the Marine diversion in the south had drawn the Japanese forces to that area. While the real attack forces approached by a roundabout route, covered by an early morning fog and artificial smoke, the approach of the diversion troops had been in full view of the enemy. Again, the Japanese might be conserving their strength for a bold counterattack as soon as American forces should be irrevocably committed to the beaches; but the time for such a counterattack came and went and still the enemy gave no sign.
The truth was, as the Americans were soon to discover, that the enemy was indeed on Okinawa in great strength, and that he had a well-thought-out plan for meeting the invasion.{152}
The task of defending the Ryukyus was entrusted to the Japanese 32d Army, commanded by Lt. Gen. Mitsuru Ushijima.{153} General Ushijima had assumed command in August 1944, relieving Lt. Gen. Masao Watanabe who had activated the 32d Army in the preceding April. On assuming command, General Ushijima and his chief of staff, Lt. Gen. Isamu Cho, had reorganized the staff of the Army, replacing the incumbents with bright young officers from Imperial Headquarters. As reconstituted, the staff was distinguished by its youth, low rank, and ability. Col. Hiromichi Yahara, the only holdover from the old staff, was retained as senior staff officer in charge of operations.
General Ushijima, according to the members of his staff, was a calm and very capable officer who inspired confidence among his troops. He had commanded an infantry group in Burma early in the war and came to his new assignment from the position of Commandant of the Japanese Military Academy at Zama. General Cho was a hard-driving, aggressive officer who had occupied high staff positions with the troops in China, Malaya, and Burma and had come to Okinawa from the Military Affairs Bureau of the War Department in Tokyo. Colonel Yahara enjoyed the reputation of being a brilliant tactician, conservative and calculating in his decisions. The combination of Ushijima's mature judgment, Cho's supple mind and aggressive energy, and the shrewd discernment of Yahara gave the 32d Army a balanced and impressively able high command.{154}
Prior to the activation of the 32d Army on 1 April 1944, Okinawa had been defended by a small and poorly trained garrison force. In June, before the American landings in the Marianas, the Japanese planned to reinforce the garrison with nine infantry and three artillery battalions.{155} The first reinforcement to reach Okinawa was the 44th Independent Mixed Brigade, which arrived late in June. The 9th Division landed on the island in July and was followed in August by the 62d Division and the 24th Division. Artillery, supporting troops, and service elements arrived during the summer and fall of 1944.
The Japanese plans for the defense of the Ryukyus were disrupted when the veteran 9th Division left Okinawa for Formosa early in December, as part of the stream of reinforcements started toward the Philippines after the invasion of Leyte. It was intended to replace the division, but shortage of shipping made this impossible. Of the remaining combat units, the 62d Division was considered by the commanding general and his staff to be the best in the 32d Army. Commanded by Lt. Gen. Takeo Fujioka, the division was formed from the 63d and 64th Brigades, each consisting of four independent infantry battalions which had fought in China since 1938. It lacked divisional artillery but by April 1945 had been brought up to a strength of about 14,000 by the addition of two independent infantry battalions and a number of Boeitai (Okinawa Home Guards).
JAPANESE COMMANDERS on Okinawa (photographed early in February 1945). In center: (1) Admiral Minoru Ota, (2) Lt. Gen. Mitsuru Ushijima, (3) Lt. Gen. Isamu Cho, (4) Col. Hitoshi Kanayama, (5) Col. Kikuji Hongo, and (6) Col. Hiromichi Yahara.
As finally organized, each of the independent infantry battalions was composed of five rifle companies, a machine gun company, and an infantry gun company, with a total battalion strength of approximately 1,200 men. (See Chart V.)
Unlike the 62d Division, the 24th was a triangular division, consisting of the 22d, 32d, and 89th Infantry Regiments and the 42d Field Artillery Regiment; it had never seen combat. In January 1945 each of the infantry regiments had incorporated 300 Okinawan conscripts into its ranks and had been reorganized. After the reorganization a regiment consisted of three battalions of three rifle companies each, with each company reduced from 290 to 180 men. The total strength of the division, including Okinawans, was more than 15,000.
The 44th Independent Mixed Brigade consisted of the 2d Infantry Unit and the 15th Independent Mixed Regiment and had a strength of about 5,000 men. The brigade had lost most of its original personnel by American submarine action while en route to Okinawa in June 1944, and it had been reconstructed around a nucleus of 600 survivors. The latter, plus replacements from Kyushu and conscripted Okinawans, were reorganized into the 2d Infantry Unit, of approximately regimental strength but without a full complement of weapons and equipment. The 15th Independent Mixed Regiment was flown to Okinawa at the end of June 1944 and assigned to the brigade. In addition to its three battalions of infantry, it had engineering troops and an antitank company; by the addition of native conscripts and Boeitai it had been brought by April 1945 to a strength of almost 2,800 men.
To add to the three major combat infantry units, General Ushijima in February 1945 converted seven sea-raiding battalions, formed to man suicide boats, into independent battalions for duty as infantry troops to fill the serious shortage resulting from the withdrawal of the 9th Division. These battalions had a strength of approximately 600 men each and were divided among the major infantry commands. Counting these additions there was a total of thirty-one battalions of infantry on Okinawa, of which thirty were in the southern part. Independent artillery units constituted an important part of the reinforcements sent to Okinawa. Two regiments of 150-mm. howitzers, one regiment of 75-mm. and 120-mm. guns, and one heavy artillery battalion of 150-mm guns were on the island by the end of 1944 to supplement the organic divisional artillery and infantry cannon. For the first time in the Pacific war, Japanese artillery was under a unified command; all artillery units, with the exception of divisional artillery, were under the control of the 5th Artillery Command. Most of the personnel of the command, which numbered 3,200, had served in other campaigns and had been with their units for three or four years. They were well trained by Japanese standards and were considered among the best artillerymen in the Japanese Army.
CHART V — Organization of the Japanese 62d Division in Okinawa
About 10,000 naval personnel were organized into the Okinawa Naval Base Force, commanded by Rear Admiral Minoru Ota, which had control of all naval establishments and activities in the Ryukyus. The unit was largely concentrated on Oroku Peninsula and just before the American landings was reorganized as a ground combat force for the defense of the peninsula. Only about 200 of the Force, however, had had more than superficial training in ground combat.
Other important units on Okinawa included the 27th Tank Regiment of about 750 men, 4 independent machine gun battalions totaling over 1,600 men, an independent mortar regiment of 600 men, 2 light mortar battalions comprising 1,200 men, 4 antiaircraft artillery battalions totaling 2,000 men, 3 machine cannon battalions with 1,000 men, and 3 independent antitank battalions and 4 independent antitank companies totaling about 1,600 men. There were also from 22,000 to 23,000 service troops of various kinds.
At the time of the American landings on Okinawa, about 20,000 Boeitai had been mobilized by the Japanese for duty as labor and service troops. Though these men were for the most part not armed, they performed valuable services as ammunition and supply carriers at the front lines and also engaged in numerous front-line and rear-area construction and other duties. Some eventually saw combat. The Boeitai are not to be confused with the Okinawan conscripts and reservists who were called up and assimilated into the regular army just as were the Japanese in the home islands. The first group of Boeitai was assembled in June 1944 to work on the construction of airfields, but the general mobilization of natives into "National Home Defense Units" was not ordered until January 1945, after the departure of the 9th Division. About 17,000 Okinawans between the ages of seventeen and forty-five were drafted to serve as Boeitai. In addition, about 750 male students of the middle schools, fourteen years of age and over, were organized into Blood and Iron for the Emperor Duty Units and trained for guerilla warfare. Further drafts of Boeitai were made at various times during the battle. In addition to the Boeitai a large number of Okinawan civilians were conscripted into the Japanese forces either to increase the strength of existing units or to organize new units. While the actual number of Okinawans serving with the 32d Army has not been determined, available evidence indicates that they represented a large proportion of the total, increasing the Japanese strength by perhaps as much as one-third or more.{156}
50-mm. Grenade Discharger