TOKYO 22 October 1945
Interrogation of: Capt. OHMAE, Toshikazu, IJN, a naval officer of 25 years service, who was on the Staff of the Southeast Area Fleet from June 1942 to December 1943. From December 1943 he was on the Staff of the First Mobile Fleet and took part in the planning and execution of the operations for the defense of the MARIANAS and of the PHILIPPINES.
Interrogated by: Captain Steadman Teller, USN.
Allied Officers Present: Lt. Comdr. D.P. Aiken, USNR.
Captain OHMAE summarizes the plans for defense of the MARSHALLS-GILBERTS and explains reasons for changes in plans. He also provides information on a few interesting points in connection with the reinforcement of Japanese Air in the SOLOMONS Campaign.
Q. What plans were made for defense of the MARSHALLS-GILBERTS?
A. In May 1943, there was a conference at TRUK between the CinC of the Southeast Area, Vie Admiral KUSAKA, and the CinC Second Fleet, Vice Admiral KONDO. At this conference it was decided: first, to bring out as many reinforcements as possible from JAPAN; and second, to hold the SOLOMONS and the DAMPIER Strait Area in the BISMARCKS. The emphasis on aircraft reinforcements was in the SOLOMONS and reinforcements to the MARSHALLS-GILBERTS were to be principally in the form of troops. The possibility of U.S. attack in any of the MARSHALLS-GILBERTS, SOLOMONS and Eastern NEW GUINEA Areas was realized; therefore, the Second Fleet was to be concentrated at TRUK to meet any eventuality. Japanese aircraft were concentrated in the SOLOMONS, but there were relatively few in the Central PACIFIC due to shortage.
The specific plan to counter an American invasion of the GILBERTS was as follows: Long-range aircraft from the BISMARCKS would attack the U.S. invasion forces and then land at fields in the MARSHALLS-GILBERTS. Short range aircraft would start from or stage through TRUK and proceed to MARSHALLS-GILBERTS fields and from there attack the U.S. forces. It was expected to require four days for the short range aircraft to reach the attack position from the BISMARCKS. Warships at TRUK would sortie and move to the GILBERT Islands where they would attack American surface and invasion forces. Six or seven submarines, which were employed in supply service in the BISMARCKS, also would be ordered to assist in repelling the invasion.
Two factors radically changed these plans. The first was the serious damage received by several Second Fleet cruisers at RABAUL by carrier air attack on 5 November 1943. These ships and other units had just arrived from TRUK to assist in the serious situation at BOUGAINVILLE. The second factor was the intensified air war in the SOLOMONS related to further landings at MUNDA which absorbed our air forces already in the Western SOLOMONS and also required employment of the short range planes which were being held at TRUK for defense of the MARSHALLS-GILBERTS. Consequently the original plans for defense of those islands could not be carried out when American forces invaded in November, because there was insufficient surface and air strength available to make effective resistance.
Q. How were the Second Fleet aircraft carriers employed during the summer and fall of 1943?
A. They were principally employed in transporting aircraft material and personnel from the EMPIRE to the Central and South PACIFIC. The air groups of these carriers (JUNYO, RYUHO, HIYO) had been sent to the North SOLOMONS in July to meet the serious situation created by the American landings.
Q. What losses were sustained during ferrying operations from the EMPIRE to outlying bases?
A. Until the summer of 1943, we averaged about 6 or 7 percent, but the percentage increased rapidly after that. The greatest loss in any one operation was 30 percent. The loss in this type operation was heavier in the case of Army planes. For example 24 Army planes took off from TRUK in June 1943 and only two arrived in RABAUL. This was the first TRUK to RABAUL flight by Army planes
without a Navy plane leading. The first group of Army planes arrived in April 1943. The largest number of Army planes to be in the SOLOMONS Area at one time was believed to have been 100. This averaged about one third of the naval air strength in the SOLOMONS.
Q. How was the planning done for participation of Army and Navy aircraft in a joint operation?
A. The planning was done in the Imperial Headquarters, TOKYO. IN the SOLOMONS Campaign, it was planned that Army and Navy strength available would be about equal. This was not realized, although the allocations of Army aircraft and numbers actually taking off from JAPAN for the campaign area were approximately those of the planned proportion. However, the number to arrive at destination was far below that because of troubles such as poor maintenance en route, and the long route followed by the comparatively short ranged Army planes, also poor overwater navigation. The route followed by the small Army planes was usually RYUKYUS, FORMOSA, PHILIPPINES and NEW GUINEA. Some, however, were transported by ship to TRUK and then flow to RABAUL. The larger and long range Army planes flew the more direct route from IWO, SAIPAN, TINIAN, TRUK, and to RABAUL.
Q. Were Army aircraft able to use naval radio facilities for navigation?
A. The Army aircraft radio equipment was not such design as to make good use of naval radio facilities along the ferry route.
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