Disaster in the Truk Atoll -Desperate War of Japan in the Pacific

1. Disaster in the Truk Atoll

Desperate War of Japan in the Pacific
This page contains Japanese characters.

Air raid at the Marsharl Islands on 1 February 1942

Signal intelligence of IJN at Truk warned an enemy action on 31 January 1942. The 4th fleet in Truk did not response and did a drinking party then. USS Enterprise and Yorktown attacked the Martial Islands on 1 February. A few hevy crusiers were bombarded. Port master of Truk reported in and out warships every day as usual on peace.^[1] So HYPO knew when X in and out Truk.

Japanese merchant ships sunk in Truk Atoll

Merchant ships sunk on 17 and 18 February 1944
Kanji	Name	GT	Kind
第3図南丸	3rd Tonanmaru
19,206	oiler
神国丸	Kamikunimaru	10,020	oiler
富士山丸	Fujisanmaru	9,527	oiler
りおでじゃねいろ丸	Rio de Janeiro	9,626	Submarine tender
平安丸	Heianmaru	11,614	Submarine tender
愛国丸	Aikokumaru	10,437	Aux cruiser
赤城丸	Akagimaru	7,386	Aux cruiser
清澄丸	Kiyozumimaru	6,983	Aux cruiser
日豊丸	Nippoumaru	3,763	-
麗洋丸	Reiyoumaru	5,445	-
伯丸	Houkimaru	7,112	-
北洋丸	Hokuyoumaru	4,216	-
宝洋丸	Houyoumaru	8,691	-
富士川丸	Fujikawamaru	6,938	-
第６雲海丸	6th Unkaimaru	3,220	-
西江丸	Nishiemaru	5,385	-
桃川丸	Momokawamaru	3,829	-
五星丸	Goseimaru	1,931	-
第１５昭南丸	15th Syounanmaru	355	-
長野丸	Naganomaru	3,824	-
桑港丸	Kuwaminatomaru	5,831	-
松丹丸	Syoutanmaru	1,999	-
山霧丸	Yamagirimaru	6,349	-
乾洋丸	Kenyoumaru	4,861	-
夕映丸	Yubaemaru	3,217	-
大邦丸	Taihoumaru	2,829	-
天城山丸	Amagiyamamaru	7,620	-
山鬼丸	Yamaonimaru	4,776	-

An enemy aircraft appeared over Truk Atoll at 8am on 4 February. Another large aircraft flew to Truk Atoll on 7 January 1944. Grand Fleet was anxious about an air raid. So battleship Musashi of flag ship of Grand Fleet left for Yokosuka. She was escorted by cruiser Oyodo, destroyer Michisio and Shiratsuyu on 10 February. Other warships fled to Palau.
Nakajima, p164-166

Where did the large aircraft fly from? US ground force landed at Kwajalein Atoll on 2 February. The distance from Truk to Finschhafen, Kwajalein, Port Moresby and Guadalcanal are 1,610km, 1,780km, 1,920km, 2,080km each. A PB4Y-1 of VMD-254 did a photo-reconnaissance mission from Mono Island to Truk on 2 February 1944. The distance and azimuth are 1,690km and 345°. The PB4Y-1 returned to Bougainville Island. The return distance and azimuth are 1,560km and 166° The round distance is 3,250km. Average cruise speed was 271 km/h, as it took 12 hours. The average speed is 16% slower than nominal speed 322 km/h (B-24D). VMD-254 completed 300 photo-reconnaissance sorties before it returned to the US at the start of 1944. Was the PB4Y-1 was PBY-1P, considering the mission and the long flight?
Dorr, p43
B-24, p24
MARINE PHOTOGRAPHIC SQUADRON 254 (VMD-254) HISTORY

Signal intelligence caught a signal of USN aircraft carrier at noon on 15th. 4th Fleet ordered alert at 0230 on 16th, and flew 11 aircraft to patrol. They did not find any sign of enemy TF, 4th Fleet erased the alert at 1030.

USN TG58 attacked Truk during 2 days on 17 to 18 February 1944, when IJN aircraft carrier Zuikaku was in Singapore. USN torpedo planes attacked before dawn of 18th. They would be able to use airborne radars.
Zuikaku Kodo Nenpyo

I list up lost transports, oilers and submarine tenders. Although Aikokumaru, Akagimaru and Kiyozumimaru were auxiliary cruisers, IJN had changed their warship kind into auxiliary transport in October 1943. Auxiliary cruiser could not combat like WWI. Akagimaru sank just running out of Truk, 512 personnel were KIA in the ships. Japan lost 9 warships and 34 merchant ships. The 9 warships were 2 submarine chasers and 4 destroyers (Maikaze, Oikaze, Tachikaze and Fumidzuki) and light cruisers (Naka, Katori). Light cruiser Agano was sunk out of the atoll. 600 personnel were KIA or wounded on land. IJN lost 17,000t of oil and 2,000t of stored food.
Ohi, p181-186
Senji, p122-124
Giken, p206
Nimitz, p245-247

The 3rd Tonammaru was the largest merchant ship in Japan. It engaged in whale catching before. IJN used it as oiler. It was salvaged after the war, and engaged in whale catching again to supply Japanese people with protein.^[2]

While 17 planes of TG58 were shot down with the loss of 29 airmen only. US lost 25 aircraft (12 fighters, 7 TBF, 6 bombers).

IJN air defense force over Truk

Defense force
Eten Island (Take shima) 204th Kokutai 31 Zeros 501st Kokutai 25 Zeros 201st Kokutai 8 Zeros
Moen Island (Haru shima) 753rd Kokutai 10 land-based bombers 552nd Kokutai 15 bombers 582nd Kokutai 7 torpedo bombers, 2 Jills 4th Base 8 seaplanes
Parm Island (Kaede shima) 551st Kokutai 26 Jills 251st Kokutai 9 night fighters 938th Kokutai 5 Zeros
Dublon Island (Natsu shima) 6th Fleet 7 seaplanes 4th Base 11 seaplanes

IJN had 69 Zeros in airfields of two islands, total of 169 aircraft in 4 islands of Truk Atoll then. These were, Radars in Truk caught the enemy at 0425 on 17th. 60 Zeros took off and 40 of them intercepted F6F. 28 crews of the aircraft were lost during 9 aerial combats of the day. While 10 Jills and 9 bombeers flew to attack the Task Force, 15 were lost. 5 Betties also attacked it from Tinian, one of them torpedoed and broke some propulsion machinary of USS Intrepid (CV-11). The next before dusk, TBF attacked the harbor using their own radars. Enemy aircraft destroyed 3 fuel tanks, 200 aircraft in depot for Rabaul and Eniwetok Atoll on sight.
Bei Kido Butai no Truk Kusyu

Aftermath

Though IJN offical checked how the disaster occurred, Commander Kobayashi Masami was not responsible at all. In the replace of him, Minister of Transportaion Hatta Yoshiaki was fired.^[3] I do not know the reason. In fact, IJN oustered Commander of 4th fleet Kobayashi Masami.^[4] He was one of a few flag officers who were responsible for the defeat or mistake. But the same disaster occurred in Palau again on 30 May 1944.

2. Palau raid

Lost tankers at Palau raid
Kanji	Name	GT
あけぼの丸	Akebono-maru	10,121
朝潮丸	Asashio-maru	5,141
大瀬	Ouse	15,000
石廊	Irou	15,400
佐多	Sata	15,400

Battleship Musashi, a flag ship of GF (Grand Fleet) fled to Yokosuka on 10 February 1944 before Truk disaster by USN air raid on 17 February. Musashi departed from Yokosuka on 24 February and arrived at Palau on 29. An intelligence staff of Grand Fleet judged that US aircraft carriers were running to Palau on 27 March by hearing enemy wireless communications.

28 March
A patroling aircraft telegrammed seeing aircraft carriers
29 March
At noon an aircraft reported enemy was comming near the south of Palau at 16 kt. GF staffs of Musashi landed. Musashi was ordered to run to the north of Palau, and was torpedoed by a US submarine on leaving Palau. So Musashi left for Kure and accompanied destroyers.
30 March
0530 30 Zeros of 201st Air Group and 12 Zeros of 501st Air Group intercepted carriers aircraft. The 201st lost all of Zeros. The rest of Zeros could not 2nd raid any more. The enemy released magnetic mines. 32 Zeros of 261st and 25 Zeros of 263rd arrived at Peleliu from Saipan after the sunset, when 8 of them were damaged because of holes in airstrip. The 57 Zeros flew 1,550km azimuth 235° from Saipan. Though 16 Betties attacked the task group in the evening, no hits. When 12 Judies searched the enemy from Saipan, they were attacked F6F and heavily lost. Were the Judies spotted by a USN radar? Did CIC control USN fighters by wireless phone? The GF head quater was to Saigon via Davao
31 March
dawn a few betties attacked the task group. No hits.
0620 alert. 28 Zeros of the 261st and 18 Zeros of the 363rd intercepted. All of them were lost, heavily damaged and burned.
1440 Enemy raid ended.
2200 2 Emily took off on board of GF staffs.

IJN aircraft deployment
Mariana 109 Zeros (261st, 263rd) 65 aircraft (65th Air Squadron)

Central Caroline 113 Zeros (202nd, 301st) 76 aircraft (22nd Air Squadron)

Peleliu 33 Zeros (201st, 501st) 31 aircraft (26th Air Squadron)

How did 113 Zeros of the Central Caroline Islands action during air combats? 50 aircraft of 26th air squadron and 90 of 1st air fleet were lost at the air combats. I think USN aircraft were controlled by CIC in an aircraft carrier. Koga, a commander of GF was lost on a flying boat by bad weather. IJN missed the GF commander again like Yamamoto. Koga was hornored as a martial in spite of 23 merchant ships loss (100kGT) and 7 warships loss. 23 ships included 7 fleet oilers. Sunk Akashi was only one workship. GF did not warn merchant ships. GF ordered the port head quater that merchant ship convoys stayed at Palau, though GF knew comming raid two days ago. Messengers informed merchant ships of raid warning by boat at night. During air raids, captains of merchant ships thougt that their ships had better be sunk in the habor. So they could save their crews' lives. Escort force may order merchant ships to flee after the disaster whether GF will order or not.
Nakajima p172-179
Ohi, p204-206
Palau Dai-kushu
Mariana Islands no shikkan

[1] Chihaya ge, p53
[2] Ouchi p.279-290
[3] Ohi, p186
[4] Kobayashi Masami