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27 Oct 1945

ww2dbaseDOI, Yasumi, Commander, I.J.N.

DOI served 17 years in the regular Navy, specializing in gunnery. In 1942 he was a member of the Army-Navy Total War Research Institute to study economic problems of the war. in March 1943 he was ordered as Gunnery Officer on the staff of the Commander, Southeastern Area Fleet, located in RABAUL. In this position he was responsible for the anti-aircraft defense and ordnance supply of the naval airfields in the RABAUL-SOLOMONS-BISMARK Area. He was also concerned with the mining operations. Since demobilization DOI has been serving as a member of the House of Peers.

This officer answered all questions freely and accurately, although he appeared critical of the Japanese Army's efforts in the defense of the SOLOMONS. (This attitude was also in evidence among other officers that were stationed in this area during the SOLOMONS Campaign.)

Gunnery Officer, Aoba (CA)		November 1941-March 1942
Army-Navy Total War Research Institute		March 1942-March 1943
Staff Gunnery Officer, Southeastern Area Fleet	RABAUL	March 1943-March 1945
Staff Officer, Bureau of Military Affairs	TOKYO	March 1945-August 1945

Interrogation

INTERROGATION NAV NO. 52
USSBS NO. 224
RABAUL

TOKYO
27 OCTOBER 1945

Personnel interrogated and background of each:

Interrogation of: Commander DOI, Yasumi, IJN ; Gunnery Officer, Staff South Eastern Fleet March 1943-1945, Based at RABAUL.

Interrogated by: Captain C. Shands, USN.

Summary:

About 200 Japanese Navy planes and 60,000 troops operating from RABAUL against the American advance in the SOLOMONS. U.S. heavy-bombing raids seriously damaged landing strips but never put all strips out of commission at the same time. Harbor shipping severely damaged by dive-bombers. Mining of RABAUL not effective. Effective mining in MUNDA, BUIN and KAVIENG. Radar on Cape ST. GEORGE gave about one hour warning of approach of U.S. aircraft from the SOLOMONS but carrier raids came as a surprise. Bombardment of installations not very effective. Sufficient food and supplies but deficient in anti-aircraft ammunition. U.S. occupation of SOLOMONS stopped Japanese expansion to the southeast. Initial turn of the war considered occurred at MIDWAY forcing new naval tactics. Naval air losses in SOLOMON Campaign detrimental to later defense. Loss of shipping had severe economic effect upon end of war.

Transcript:

Q. Who was in command at RABAUL while you were there?
A. Vice Admiral KUSAKA in charge of naval installations, General IMAMURA in charge of the Army. They had equal authority.

Q. How many airfields did you have in operation?
A. Three Navy fields: (1) East Airfield (2) West Airfield (UANARANAU) and TOBERA Airfield. There were also two Army air strips but they were not much good.

Q. How many planes were based there?
A. The Navy had a maximum of about 200 planes. The Army had hardly any. Only a few search planes, but they did not fly very much. Most of the Army planes were in BURMA. The tactical ideas of the Army and Navy were not the same so there was no good coordination between them. There were seaplane facilities but only a few operated there. Not over twelve. After they began to operate they found it was too difficult so they just dwindled away. After that they only came with supplies. All planes were fueled from 200 liter drums.

Q. What was the effect of our air raids upon RABAUL?
A. When the heavy-bombers came, the landing strips were seriously damaged but there were not very many casualties. The dive-bombers were very serious against ships and did practically all of that kind of damage. One day, about 11 November 1943, was a bad one. Dive-bombers sank four supply ships in the harbor. I don't remember the names. Against supply dumps, the damage was about the same between heavy-bombers and divebombers. After the planes left for TRUK in February 1944, your targets shifted to strafing of personnel. That was very distressing.

Q. How long did it take to repair the runways after a bombing raid?
A. Usually about 10 hours. Since all of the fields were never bombed at one time, the bombing of the fields was not too serious. However, if planes tried to land on the damaged fields or on the Army fields which were very rough, they usually were damaged. If all fields had been bombed at the same time it would have been serious.

Q. How effective were the mining operations?
A. The water at RABAUL was about 60 meters deep so it was not very effective. We did not even sweep. I do not think that any ships were sunk there from mines. In MUNDA, BUIN and KAVIENG the mines were very serious and there were many casualties. I do not remember how many.

Q. Did you have any radar installations at RABAUL?
A. Yes, we had a secret one, well hidden on Cape ST. GEORGE. It could pick up planes about 100 Kilometers away. We also had coast watchers with radio at BUIN and EMPRESS AUGUSTA Bay. We generally had about an hour's notice of the approach of your planes from GUADALCANAL. That was enough time to man our guns and put up fighters. Carrier attacks would sometimes surprise us.

Q. Did you have any fire control radar?
A. The first anti-aircraft radar fire control equipment was brought down about September 1943. It was the first Japanese equipment of its kind. It did not work very well, and was broken completely in October 1943. We tried having fighters fly alongside bombing formations to give us the altitude and speed, but due to communication difficulties that did not work very well. The heavy-bombers always came over at the same altitude, so we thought we knew it pretty well; but we missed a little on speed. We think that we shot down several hundred American planes, including those that were damaged and did not get back to their base.

Q. Who manned your guns?
A. It was about half Army and half Navy. The Navy manned all guns over 12.7 cm. We had 12 x 12.7cm. guns, 8 x 12cm. guns and about 60 other AA guns. In addition we had about 200 x 20mm. machine guns.

Q. Did you have adequate ammunition?
A. No, we were always very short of anti-aircraft ammunition. It was normally brought in by transport, but as shipping conditions became more difficult, due to aircraft attack, it was brought in on destroyers. About October 1943 it was brought in twice by submarine.

Q. How many shore-based personnel did you have at RABAUL?
A. About 3300 Navy. About half of these were Navy labor battalions. The rest were garrison troops. There were no special landing troops there. Prior to April 1943 there were very few Army troops at RABAUL, but after that about 60,000 were drawn in from the western end of the island.

Q. Did you expect the Americans to land at RABAUL?
A. There was divided opinion. The Navy thought that it would not be profitable and unnecessary for you after you captured LAE and SALAMAUA and started through the MARSHALLS-GILBERTS. The Army thought that you would, so moved in all the troops. When you went into the MARIANAS we were sure that you would by-pass us. At that time it was not important that you capture RABAUL, since it was not contributing to our defense of the EMPIRE.

Q. How did you get your aircraft to RABAUL?
A. Most of the Navy planes flew in, either from the PHILIPPINES or from TRUK. The Army flew in a few, but they had navigation losses so later brought them in by ship. The ships generally passed around the northwest end of NEW IRELAND but sometimes to the south depending upon the intelligence we received about your patrolling submarines.

Q. What aircraft squadrons were based at RABAUL?
A. It was the Eleventh Air Fleet, 25th and 26th Squadrons, composed of fighters and bombers. Sometimes the squadrons varied.

Q. Were you present during any ship bombardments?
A. Yes, I was at MUNDA and VILLA. There was very little damage, but it was very fearsome. Not very accurate. Sometimes we couldn't even find where the shells landed. We were kept sleepless and fatigued. Sometimes fuel or supplies would be hit. Mostly just damaged airfield.

Q. Were any of the American planes that were shot down shipped back to JAPAN?
A. I do not think so, but the radio equipment was removed and shipped.

Q. Did you have any motor torpedo boats operating in that area?
A. At one time we had a few at the southern end of BOUGAINVILLE, but they were mechanically imperfect and we stopped using them. Some boats which were to be used against battleships were at SHORTLAND but , they were not successful.

Q. How did you control your night fighters?
A. Only with searchlights. They did not have radar. Only two would be up at a time.

Q. How did you maintain supply lines to your bases in the SOLOMONS?
A. Early in 1943 we used destroyers. Later we used small boats. Boats entered a secret harbor on NEW GEORGIA opposite ARUNDEL Island. They operated at night and were hidden during the day. The ships were not over 500 tons.

Q. Did you expect us to land at MUNDA?
A. Yes. We planned to mine it by aircraft, but the mines did not arrive in time. Later we had trouble with them so did not use them. The weather was also bad for mining. Three days before you landed, we mined it by using destroyers.

Q. When you were on RABAUL did you receive information when other islands were occupied?
A. Yes, we received immediate radio notice from the SOLOMON ISLANDS. We also knew when KWAJALIEN, GUAM and SAIPAN were captured.

Q. What effect did the loss of the SOLOMONS have upon your plans?
A. It stopped our expansion to the southeast. Our original plans did not call for expansion, but when we got to the SOLOMONS we thought that we should go further. We did not plan to capture AUSTRALIA, but we thought that we might go as far as the NEW HEBRIDES. When you captured the SOLOMONS, our orders at RABAUL were to hold there. It was very expensive to the Japanese Navy to try to recapture GUADALCANAL. We lost many pilots and planes which we needed later. Also lost ships. The Army lost many trained men.

Q. What factors caused you to lose the war?
A. I was a student in our Army-Navy Research Institute and Staff of the Bureau of Military Affairs. We were studying the total war, hoping that we might find some way to win. We felt that on the whole the Navy was placed in a situation which was under the general management of the Army. If the Army and Navy had studied it more widely, we would have done better. After our first success at PEARL HARBOR and CEYLON we received a severe setback at MIDWAY. I think that was the first turn of the tide. We had to change our naval plans but did not have many big carriers to do it with. We also studied economic and morale subjects like fuel, and iron. We thought that we could hold on for a long time, but in the end the destruction of our shipping was very bad for us.

Q. How large were the guns on the Musashi and Yamato?
A. In the Navy College we were not permitted to talk about those ships. The guns were listed as "40 Special". I think that they were 46cm. (about 18 inches). ww2dbase

Source(s):
United States Strategic Bombing Survey (Pacific) Interrogation of Japanese Officials [OPNAV-P-03-100], courtesy of ibilio Hyperwar Project

Added By:
C. Peter Chen

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