ZATSUYOSEN!

(SHOUN MARU at Rota, Marianas 23 Jun ‘44)

IJN SHOUN MARU:
Tabular Record of Movement

© 2013 Gilbert Casse, Bob Hackett and Peter Cundall


29 May 1940:
Tama. Laid down by Mitsui Bussan K.K. Zosensho shipyard for Matsuoka Kisen K.K. as a 4,396-ton cargo ship.

13 March 1941:

Launched and named SHOUN MARU.

27 June 1941:
Completed and registered in Ashiya.

7 November 1941:
Conversion to military duty is completed.

14 November 1941:
Requisitioned by the IJN.

15 November 1941:
Registered in the IJN as an auxiliary transport, (Otsu) category and attached to the Sasebo Naval District with Sasebo as homeport under internal order No. 1419. [1]

1 December 1941:
Arrives at Osaka, Hyogo Prefecture.

5 December 1941:
Departs Osaka.

6 December 1941:
Arrives at Tsukumi, Oita Prefecture.

8 December 1941:
Departs Tsukumi.

10 December 1941:
Arrives at Yokkaichi, Mie Prefecture.

15 December 1941:
Departs Yokkaichi.

16 December 1941:
Arrives at Yokosuka.

17 December 1941:
Departs Yokosuka and arrives at Tokyo later that same day.

19 December 1941:
Departs Tokyo.

27 December 1941:
Arrives at Palau, Western Carolines.

4 January 1942:
At 0800, departs Palau and arrives at Peleliu, Palaus, at 1045.

9 January 1942:
At 1215, departs Peleliu.

14 January 1942:
At 1630, arrives at Takao, Formosa (now Kaohsiung, Taiwan).

18 January 1942:
At 0830, departs Takao.

19 January 1942:
At 1745, arrives at Kirun (now Keelung), Formosa.

21 January 1942:
At 0815, departs Kirun.

27 January 1942:
At 1000, arrives at Palau.

1 February 1942:
At 0700, departs Palau.

5 February 1942:
At 0600, arrives at Saipan, Marianas.

14 February 1942:
At 1700, departs Saipan.

20 February 1942:
At 1130, arrives at Yokosuka. At 1500, departs and arrives at 1615 at Yokohama.

22 February 1942:
At 0600, departs Yokohama.

23 February 1942:
At 1115, arrives at Yokosuka.

24 February 1942:
At 0700, departs Yokosuka.

25 February 1942:
At 1700, arrives at Yokkaichi.

27 February 1942:
At 0615, departs Yokkaichi.

1 March 1942:
At 1630, arrives at Miike, Fukuoka Prefecture.

2 March 1942:
At 1730, departs Miike.

22 March 1942:
At 1000, arrives at Kwajalein, Marshalls.

27 March 1942:
At 1515, departs Kwajalein.

29 March 1942:
At 0630, arrives at Taroa, Marshalls.

31 March 1942:
At 1200, departs Taroa.

1 April 1942:
At 1400, arrives at Jaluit, Marshalls.

10 April 1942:
At 1315, departs Jaluit.

17 April 1942:
At 1815, arrives at Guam (renamed Omiya-Jima after its capture), Marianas.

19 April 1942:
At 1645, departs Guam.

20 April 1942:
At 0915, arrives at Saipan.

28 April 1942:
At 0500, departs Saipan and arrives off Charanka Point (now Chalan Kanoa), Saipan at 0600.

2 May 1942:
At 0445, departs Charanka Point and arrives at Tinian, Marianas at 0715.

5 May 1942:
At 0830, departs Tinian and arrives off Saipan at 1115.

7 May 1942:
At 0445, departs Saipan and arrives at Tinian at 0800.

12 May 1942:
At 1815, departs Tinian and arrives off Saipan at 2100.

15 May 1942:
Departs Saipan. That same day, SHOUN MARU is scheduled to be fitted with one 7.7mm Type A MG and five Arisaka Type 38 rifles under Navy’s Instruction No. 5990 and is removed from the Navy’s list under instruction No. 78.

16 May 1942:
Arrives at Pagan, Marianas. Departs later that day for Japan.

17 May 1942:
Attached to Yokosuka Naval District as a general requisitioned transport.

22 May 1942:
Arrives at Yokohama.

25 May 1942:
Unloads and loads cargo.

26 May 1942:
Departs Yokohama and en route joins up with a convoy consisting of IJA transport KURETAKE MARU and civilian (C-AK) TAMON MARU No. 8 escorted by auxiliary gunboat KEISHIN MARU.

28 May 1942:
Arrives at Tama, Tokyo Prefecture. Released to her owners that same day.

17 August 1942:
Requisitioned by the IJA as an Army transport will allotted number No. 819. Departs Yokohama.

E August 1942:
Arrives at Tawau, Borneo.

6 September 1942:
Departs Mutsure in convoy No. 159 also consisting of IJA transport ATLAS MARU and one unidentified merchant ship escorted by destroyer MIKAZUKI.

10 September 1942:
Arrives at Kirun.

13 September 1942:
Departs Kirun and later that day arrives at Takao.

17 September 1942:
Departs Mako, Pescadores in convoy No. 717 also consisting of IJA transport TATEISHI MARU and one unidentified merchant ship.

20 September 1942:
Arrives at Manila, Luzon.

21 October 1942:
About 120 nautical miles ESE of Wenchow (now Wenzhou), China. SHOUN MARU is hit by a torpedo from an unidentified submarine at 27-35N, 123-10E. [2]

E 1942-1943:
Released by the IJA.

20 July 1943:
At 0800, departs Takao in convoy No. 284 also consisting of auxiliary transport HIROTA MARU, auxiliary tanker MATSUMOTO MARU, IJA tanker NANEI MARU, IJA storeship BIYO MARU, IJA transports ARGUN, NORFOLK and KISHU MARUs and two unidentified merchant ships escorted by destroyer SANAE.

25 July 1943:
Arrives at Moji.

2 August 1943:
Requisitioned by the IJN as a general requisitioned transport (Ippan Choyosen) attached to the Yokosuka Naval District. Departs Tokyo and arrives later in the day at Yokohama.

10 August 1943:
Departs Yokohama and arrives at Yokosuka later that day.

15 August 1943:
Departs Yokosuka for Truk in convoy No. 3815 also consisting of auxiliary transport MUKO MARU, IJN requisitioned (B-AK) KYOWA and CHIYO MARUs and IJA transport SAN FRANCISCO MARU with destroyer IKAZUCHI as escort.

25 August 1943:
Arrives at Truk, Central Carolines.

5 September 1943:
At 1300, departs Truk for Rabaul in convoy No. 1055 also consisting of auxiliary transport YAMAFUKU MARU, IJN requisitioned (B-AK) KYOWA and CHIYO MARUs and IJA transport SAN FRANCISCO MARU escorted by subchasers CH-30 and CH- 32.

10 September 1943:
Arrives at Rabaul, New Britain.

28 September 1943:
At 1200, departs Rabaul in convoy O-803 also consisting of IJN requisitioned (B-AK) CHIYO MARU and IJA transport YAMAYURI MARU bound for Palau escorted by subchasers CH-22 and CH-24.

5 October 1943:
Arrives at Palau and loads rock phosphate.

13 October 1943:
Departs Palau in convoy FU-310 also consisting of IJA transports DAKAR, BRAZIL, CLYDE, FUKUYO, YURI, HAVRE, PACIFIC and KIBI MARUs and IJN requisitioned (B-AK) CHIYO MARU escorted by minesweeper W-18.

20 October 1943:
The convoy’s escort is bolstered by auxiliary minesweepers AOI and YACHIYO MARUs and TOKUHO MARU No. 10.

22 October 1943:
Arrives at Moji.

23 October 1943:
Departs Moji.

24 October 1943:
Arrives at Tamano, Okayama Prefecture.

25 October 1943:
Docks at Mitsui Engineering and Shipbuilding K.K. shipyard for repairs and maintenance.

8 November 1943:
Repairs are completed. Undocked.

9 November 1943:
Departs Tamano.

10 November 1943:
Arrives at Moji.

12 November 1943:
Departs Moji and arrives at Tokuyama, Yamaguchi Prefecture, later that same day.

15 November 1943:
Departs Tokuyama and arrives at Kure later in the day.

17 November 1943:
Departs Kure and arrives at Saeki, Kyushu later that day.

21 November 1943:
Departs Saeki in convoy No. O-107 also consisting of auxiliary transport KAIKA MARU, IJA transports MEXICO, CEYLON, TATSUGIKU and TATSUMATSU MARUs, and IJN requisitioned (B-AK) KAITO MARU escorted by torpedo boat SAGI, minesweeper W-22 and auxiliary minesweepers TAMA MARU No. 6 and TAISEI MARU. The auxiliary minesweepers are detached at latitude 28N and W-22 at 20N.

28 November 1943:
Arrives at Palau.

17 December 1943:
At 1200, departs Palau in convoy SO-705 also consisting of IJA transports KOYO, MEXICO, SHIRANESAN MARUs and auxiliary storeship HOKKAI MARU with unknown escort.

24 December 1943:
Arrives at Rabaul.

17 January 1944:
At 1345, departs Rabaul for Palau in convoy O-604 also consisting of IJA transports TAIAN and FRANCE MARUs escorted by subchasers CH-16 and CH-40.

22 January 1944:
Arrives at Palau.

28 January 1944:
Departs Palau and arrives at Garasumao, Babeldaob (Babelthuap), Palaus later in the day.

4 February 1944:
Departs Garasumao and arrives at Palau later that day.

18 February 1944:
At 0700, departs Palau for Takao in convoy PATA-02 also consisting of IJA transports KANKYO, MAKASSAR, MEXICO MARUs and two unidentified ships escorted by minesweeper W-18. En-route two other ships join the escort.

19 February 1944:
At 0700, patrol boat PB-31 joins as an additional escort.

24 February 1944:
Destroyer HARUKAZE joins as an additional escort.

26 February 1944:
At 1950, the convoy arrives at Takao.

29 February 1944:
Departs Takao in convoy TAMO-07 also consisting of auxiliary tankers MATSUMOTO and ASANAGI MARUs, IJN requisitioned (B-AK) BIZEN and SHOZUI MARUs, IJA transports HAVRE (5,652 GRT) and BATAVIA MARUs, auxiliary netlayer TOYO MARU No. 3 and fifteen unidentified merchant ships escorted by destroyers ASAGAO, HARUKAZE and NAMIKAZE, minesweeper W-18 and auxiliary subchaser CHa-74.

E 3 March 1944:
ASAGAO is detached.

8 March 1944:
Arrives at Osaka.

14 March 1944:
Departs Osaka.

15 March 1944:
Arrives at Wakamatsu, Fukuoka Prefecture.

17 March 1944:
Departs Wakamatsu and arrives at Tokuyama later in the day.

22 March 1944:
Departs Tokuyama.

23 March 1944:
Arrives at Osaka. Departs and arrives later in the day at Kobe.

24 March 1944:
Departs Kobe and arrives at Gobo, Wakayama Prefecture, later that day.

25 March 1944:
Departs Gobo and arrives at Mikawa Wan (Bay), Aichi Prefecture, later in the day.

26 March 1944:
Departs Mikawa Wan.

27 March 1944:
Arrives at Yokohama.

1 April 1944:
At 1100, departs Yokohama and joins convoy “Higashi-Matsu” (East pine) No. 4 also consisting of 25 other ships. The ships and their destinations are: Saipan: SHOUN, TOKO, TAKASAN, AKIKAWA, KOKO, SHIRAMINE, TAIKAI, KAKOGAWA and MACASSAR MARUs. Guam: MIMASAKA, TOAN, AZUCHISAN and NISSHU MARUs and UNYO MARU No. 8 Truk: Fleet supply ship KINESAKI, SHOZUI, TATEBE, SHIMA, SHINYO and HAVRE MARUs. Palau: Fleet supply ship MAMIYA, TENRYUGAWA, TAIAN and TOSEI MARU s and SHINSEI MARU No. 5. Yap: SHINSEI MARU. The convoy commander is Rear Admiral Kiyota Takahiko (42) (former CO of NACHI) in destroyer SAMIDARE. The other escorts include destroyer ASANAGI, torpedo-boat HIYODORI, kaibokan AMAKUSA, MIKURA, FUKUE, OKI, CD-2, CD-3 and subchaser CH-50.

3 April 1944:
5 miles S of Tori-Shima. At about 1457, LtCdr (later Rear Admiral-Ret) Bafford E. Lewellen's (USNA ’31) USS POLLACK torpedoes and sinks TOSEI MARU loaded with ammunition and rations, at 30-14N, 139-45E. Only one passenger is KIA. The escorts counter-attack POLLACK and drop 55 depth-charges without effect.

8 April 1944:
N of Saipan. At 0228 (JST), LtCdr (later Vice Admiral) Frederick J. Harlfinger's (USNA ’37) USS TRIGGER (SS-237) fires four torpedoes at the convoy, but fails to get any hits. OKI and SAMIDARE counter-attack unsuccessfully.

9 April 1944:
62 miles WNW of Saipan. At 1625, LtCdr (later Captain) Slade D. Cutter's (USNA ’35) USS SEAHORSE (SS-304) torpedoes and hits MIMASAKA MARU with 1,146 Naval personnel and 1,437-tons of luggage at 15-30N, 145-00E. One gunner, 10 crewmen and seven troops are KIA. MIMASAKA MARU is taken in tow by TOAN MARU. The escorts counter-attack SEAHORSE unsuccessfully. Later that day, SHOUN MARU is detached and arrives at Saipan.

10 April 1944:
At about 0100 (JST), MIMASAKA MARU founders.

The remainder of the convoy arrives at Saipan and then is split into separate groups that continue on to their respective destinations.

11 April 1944:
At 2300, departs Saipan.

12 April 1944:
Arrives at Guam.

19 April 1944:
Departs Guam.

20 April 1944:
Arrives at Saipan.

27 April 1944:
At 1140, departs Saipan in convoy “Higashi Matsu” No. 6 (return) also consisting of IJN requisitioned (B-AK) AZUCHISAN, TATEBE and SHOZUI MARUs, IJN requisitioned (B-APK) TOAN MARU, IJA transports AWA, AWAJI, KATSUKAWA, TAKAOKA, TONEGAWA and HOKUSHIN MARUs and three unidentified ships escorted by Rear Admiral Matsuyama Mitsuharu's (40) (former CO of KITAKAMI) 7th Convoy Escort Group's consisting of destroyer HOKAZE (F), kaibokan MIYAKE, AMAKUSA, CD-6 and CD-10, minelayer SARUSHIMA and minesweeper W-20.

4 May 1944:
Arrives at Yokohama.

7 May 1944:
Departs Yokohama and arrives at Tokyo later that day.

10 May 1944:
Departs Tokyo and arrives at Yokohama later in the day.

20 May 1944:
Departs Yokohama in convoy No. 3521 escorted by minelayers KYOSAI and YURIJIMA.

28 May 1944:
Arrives at Saipan.

9 June 1944:
Departs Saipan.

10 June 1944:
Arrives at Rota, Marianas.

12 June 1944:
Bombed by USN TF.58 Aircraft and sustains hull damage. Undergoes emergency repairs off Terunon village.

23 June 1944:
Aircraft from Rear Admiral (later Admiral) Joseph J. Clark’s (USNA ’17) carrier task group TG.58-1 bomb Japanese air facilities and shipping in the Marianas. Off Terunon village, Rota, SHOUN MARU is hit by a torpedo from USS YORKTOWN’s (CV-10) Gruman TBF “Avenger” and sinks at 14-10N, 145-10E taking down six of her crew.

(SHOUN MARU hit by a torpedo, 23 Jun ‘44)

31 December 1944:
Removed from the IJN general requisitioned list.


Authors' Notes:
[1] There were two categories of Zatsuyosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.

[2] No trace of the attack in Allied files.

Thanks go to Gengoro S. Toda of Japan.

Gilbert Casse, Bob Hackett and Peter Cundall


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