(RYUKO MARU in wartime)

Tabular Record of Movement

© 2012 Gilbert Casse, Bob Hackett and Peter Cundall

10 March 1941:
Asano. Laid down by Nippon Kokan K.K. shipyard for Taiyo Kogyo K.K. as a 2,764-ton Peacetime Standard (C) Class cargo ship.

18 December 1941:
Launched and named RYUKO MARU.[1]

16 March 1942:
Completed and registered in Kobe.

7 June 1942:
Departs Moji.

10 June 1942:
Arrives at Pukou, near Nanking (now Nanjing), China.

Her registry port is changed to Tokyo.

16 February 1943:
Arrives at Tokyo Bay from Shiogama in convoy No. 2216 also consisting of IJN requisitioned (B-APK) SHOZAN MARU and IJA transports MIYO, CHIHAYA and FUKUEI MARUs escorted by auxiliary gunboat KASAGI MARU.

23 April 1943:
Departs Yokosuka in convoy No. 7423 also consisting of auxiliary transports TATSUTAGAWA and KIZUGAWA MARUs and civilian cargo ship (C-AK) KIYOTADA (SEICHU) MARU escorted by minesweeper W-4.

25 April 1943:
Arrives at Aioi. Transfers to Osaka later in the day.

30 April 1943:
Departs Imari Wan (Bay) in convoy SA-13 also consisting of auxiliary emergency tanker SEIAN MARU, IJN requisitioned (B-AK) MENADO MARU, IJA transports TATSUHA, TAITO and SHISEN MARUs, IJA shared (A/C-AK) MAKO MARU and auxiliary transport KOTO MARU No. 2 Go escorted by minelayer TAKASHIMA. Most of the convoy is bound for Shanghai.

2 May 1943:
At 1000, due to arrive in Chusan Island Group.

2 July 1943:
Departs Mutsure in convoy No. 172 also consisting of IJN requisitioned (B-AK) ATLANTIC MARU, IJA transports MANKO, KOKI, LIVERPOOL, KENWA, ASAKA and TSUYAMA MARUs, IJA shared transports (A/C-AK) TAIKOKU and (A/C-APK) KASHIMA MARUs and IJA emergency tanker HAKUBASAN MARU with 3 of these vessels from Miike and 2 from Sasebo. The escort was destroyer KARUKAYA. The convoy leaves port in driving rain and mist and RYUKO, TSUYAMA and ASAKA MARUs become detached and return to Moji.

7 July 1943:
At 1400, departs Moji for Takao, Formosa (now Kaohsiung, Taiwan) in convoy No. 173 also consisting of auxiliary tankers KOSHIN MARU and KYOEI MARU No. 2, IJA shared tanker (A/C-AO) ZUIYO MARU, auxiliary transports HIROTA and NACHISAN MARUs, IJA transports MURORAN, ASAKA, TAIYU and KYOKKO MARUs and civilian ore carrier (C-AC) GYOKUREI MARU escorted by torpedo boat HAYABUSA and patrol PB-36.

13 July 1943:
At 0950, arrives at Takao. Departs later.

15 July 1943:
Arrives at Kirun (now Keelung), Formosa. Requisitioned that same day by the IJN as a general requisitioned transport (B-AK) and attached to the Sasebo Naval District with Sasebo as homeport.

E July 1943:
Assigned to the Department of Navy.

21 July 1943:
Departs Kirun.

26 July 1943:
Arrives at Osaka.

28 July 1943:
Departs Osaka.

29 July 1943:
Arrives at Tokuyama, Yamaguchi Prefecture.

31 July 1943:
Departs Tokuyama.

2 August 1943:
Arrives at Sasebo.

12 August 1943:
Departs Sasebo.

19 August 1943:
Arrives at Takao.

22 August 1943:
At 1000, departs Takao in convoy No. 317 also consisting of auxiliary tanker KIYO MARU, IJA shared tanker (A/C-AO) YAMAMIZU MARU No. 3, IJA transports CHOJO, KOYU, KACHOSAN KISHU and KAIKO MARUs and three unidentified merchant ships escorted by patrol boat PB-2.

26 August 1943:
Arrives at Samah, Hainan Island, China.

5 September 1943:
Departs Samah.

11 September 1943:
Arrives at Saigon, Indochina (now Ho Chi Min City, Vietnam).

23 September 1943:
Departs Saigon in convoy No. 428 also consisting of IJA shared tanker (A/C-AO) TONAN MARU and four unidentified merchant ships escorted by auxiliary gunboat PEKING MARU.

30 September 1943:
In 20-59N, 119-45E TONAN MARU reports an unsuccessful torpedo attack. Later that day arrives at Takao.

5 October 1943:
Departs Takao in convoy No. 209 also consisting of auxiliary transport HOKKAI MARU, IJA shared tanker (A/C-AO) TONAN MARU and seven unidentified ships escorted by auxiliary gunboat CHOHAKUSAN MARU.

12 October 1943:
Arrives at Moji. Departs later in the day for Osaka.

13 October 1943:
Arrives at Osaka.

16 October 1943:
Departs Osaka and arrives at Harima, Hogyo Prefecture later in the day.

25 October 1943:
Departs Harima.

26 October 1943:
Arrives at Wakamatsu, Fukuoka Prefecture.

28 October 1943:
Departs Wakamatsu and arrives later that day at Tokuyama.

20 October 1943:
Departs Tokuyama.

2 November 1943:
Arrives at Saeki, Kyushu.

6 November 1943:
Departs Saeki towing medium-sized non-propelled submergible transport No. 6 in convoy O-607 also consisting of IJA transports HOKKO, KANKYO, KANTO, HOZAN, SORACHI and TASMANIA MARUs escorted by minesweeper W-17 and auxiliary subchaser TAKUNAN MARU No. 8. Soon after departure the convoy is reinforced by auxiliary minesweepers YACHIYO MARU, TOKUHO MARU No. 10 and AOI MARU who remain until latitude 27N.

7 November 1943:
An aircraft reports five submarines ahead. At 1253, the convoy reverses course. At 1605, the convoy resumes course again.

17 November 1943:
Arrives at Palau, Western Carolines.

19 November 1943:
Departs Palau still towing medium-sized non-propelled submergible transport No. 6 in convoy SO-904 also consisting of IJA transports TASMANIA and KENZAN MARUs and civilian salvage vessel HOZU MARU escorted by subchasers CH-37 and CH-38. During the voyage south the convoy is plagued by submarine attacks.

25 November 1943:
At 1025, KENZAN MARU is torpedoed and sunk by LtCdr Oscar Hagberg's (USNA ’31) USS ALBACORE (SS-218) at 00-51N, 146-00E. Seven crewmen are KIA.

28 November 1943:
Arrives at Rabaul, New Britain.

5 December 1943:
Departs Rabaul in convoy O-504 with IJA transport KURAMASAN MARU and two unidentified merchant ships with unknown escort.

6 December 1943:
Scheduled to be fitted with a Type 3 hydrophone under Navy’s telegram No. 6083.

12 December 1943:
Arrives at Palau.

21 December 1943:
At 0900, departs Palau in convoy FU-103 also consisting of IJA transports ERIE and DENMARK MARUs escorted by torpedo boat HATO.

30 December 1943:
Minelayer YURIJIMA and auxiliary subchaser TAMA MARU No. 7 join the convoy at 29 N.

31 December 1943:
Arrives at Niihama, Shikoku.

1 January 1944:
Registered by the IJN as an auxiliary transport (Ko) category attached to the Sasebo Naval District with Sasebo as homeport under instruction No. 16. Tactically assigned to the Southeast Area. [2]

3 January 1944:
Departs Niihama.

4 January 1944:
Arrives at Wakamatsu.

6 January 1944:
Departs Wakamatsu.

7 January 1944:
Arrives at Kure.

10 January 1944:
Departs Kure.

11 January 1944:
Arrives at Kobe.

12 January 1944:
Departs Kobe in convoy No. 8112 also consisting of civilian (C-AK) MIYAJIMA MARU and government owned SHORI (ex Chinese CHONG LEE) MARU.

16 January 1944:
Arrives at Yokosuka.

2 February 1944:
Departs Yokosuka and arrives at Yokohama later that day.

4 February 1944:
Departs Yokohama and joins convoy No. 3206 bound for Truk, Central Carolines consisting of IJA transports GYOTEN (ex-British EMPIRE MOONBEAM), TATSUHA, and SHINKYO MARUs and IJN requisitioned (B-AK) ZUIKAI MARU escorted by destroyer FUJINAMI, minelayer NATSUSHIMA, kaibokan AMAKUSA and subchaser CH-31. The convoy is carrying troops of the IJA’s 52nd Infantry Division.

9 February 1944:
The convoy arrives at, and then departs Hachijo Jima.

E 16 February 1944:
Auxiliary minesweeper HAGOROMO MARU joins the convoy near Truk.

17 February 1944: American Operation "Hailstone" - The Attack on Truk:
185 miles NW of Truk. At 0228 (JST), LtCdr (later Rear Admiral-Ret) Richard H. O’Kane's (USNA ’34) USS TANG (SS-306) fires four torpedoes and gets two hits on GYOTEN MARU carrying soldiers of the 1st battalion, 150 Infantry Regiment, and elements of the 69th Infantry Regiment, 52nd division at 08-02N, 149-17E. At 0320, she splits in two and sinks a few minutes later. Eight crewmen and an unknown number of soldiers are KIA. The escorts counter-attack unsuccessfully.

In the early morning of 17 February, Vice Admiral (later Admiral) Marc A. Mitscher’s (USNA ’10) Task Force 58's five fleet carriers and four light carriers launch air attacks on Truk. Mitscher launches 30 strikes of at least 150 aircraft each. At about 1400, some of Mitscher’s planes attack convoy No. 3206. ZUIKAI MARU is hit by bombs and sinks at 1415 with unknown casualties. At 1420, TATSUHA MARU with 16 Type 95 light tanks of the 52nd Division, 1,050 men of the 2nd Battalion, 150th Infantry, 52nd Division and the division’s field hospital troops and crates full of munitions, food, and dynamite, is also hit by bombs, explodes and sinks. 535 crewmen and troops including 13 tank crewmen are KIA. After sunset destroyer FUJINAMI and kaibokan AMAKUSA return to the wreck site and rescue many survivors.

18 February 1944:
The remnants of convoy No. 3206 arrive at Truk. Mitscher launches carrier strikes about every hour for two days. During the raids, TF 58 sinks 31 merchant transports and 10 naval vessels, destroys nearly 200 aircraft and damages severely about 100 more. Truk is eliminated as a major IJN fleet anchorage.

8 March 1944:
Departs Truk.

11 March 1944:
Arrives at Woleai, Central Carolines.

16 March 1944:
Departs Woleai.

19 March 1944:
Arrives at Palau.

30-31 March 1944: American Operation “Desecrate One”:
At 0500, departs Palau in convoy PATA-07 also consisting of fleet oiler AKEBONO MARU, auxiliary transport (ex-aircraft transport) GOSHU MARU, IJN requisitioned (B-AK) RAIZAN MARU, IJA transports KIBI (1941 built), TESHIO and HOKUTAI MARUs escorted by PB-31, destroyer WAKATAKE and auxiliary subchaser CHa-26.

As soon as the convoy leaves the atoll, the anchorage is attacked by F6F "Hellcats", SBD "Dauntless", TBF "Avenger" and SB2C "Helldiver" carrier aircraft of (Task Group) TG 58. 1's USS ENTERPRISE (CV-6), USS BELLEAU WOOD (CVL-24) and USS COWPENS (CVL-25), TG 58. 2's USS BUNKER HILL (CV-17), USS HORNET (CV-12), USS MONTEREY (CV-26) and USS CABOT (CVL-28) and TG 58. 3's USS YORKTOWN (CV-10), USS LEXINGTON (CV-16), USS PRINCETON (CVL-23) and USS LANGLEY (CVL-27). The convoy is immediately dissolved and ships scatter.

Nonetheless, all merchant ships of PATA-07 are sunk. RYUKO MARU with five crewmen KIA, GOSHU MARU with the loss of 45 crewmen, AKEBONO MARU with five crewmen KIA, RAIZAN MARU with unknown casualties, KIBI MARU with the loss of five crewmen, TESHIO MARU with three crewmen KIA and HOKUTAI MARU taking down three crewmen. Patrol boat PB-31 is also sunk with unknown casualties five miles SW of Kossol Passage at 07-30N, 134-30E.

20 miles off Palau. TF 58's planes find and torpedo destroyer WAKATAKE. She goes down west of Babelthaup in Karamadoo Bay near the West Passage at 07-30N, 134-30E. Her CO, Lt Tanaka Tanaka Shigeo (64) is lost with an unknown number of sailors. He is promoted LtCdr posthumously. In all, Operation “Desecrate One” accounts for 36 Japanese vessels sunk or damaged.

30 April 1944:
Removed from the Navy’s list under instruction No. 606.

Authors’ Notes:
[1] confused with IJA transports No. 202 (2,962 GRT, ’36) or No. 343 (5,626 GRT, ’36).

[2] There were two categories of Zatsuyosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.

Thanks go to Gengoro S. Toda of Japan.

Gilbert Casse, Bob Hackett and Peter Cundall

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