(SANKO MARU, prewar)
IJN SANKO MARU:
Tabular Record of Movement
© 2016 Gilbert Casse and Peter Cundall
30 September 1938:
Sakurajima near Osaka. Laid down by Osaka Iron Works K.K. shipyard for Dairen Kisen K.K. as a 5,461-tons cargo ship.
12 February 1939:
Launched and named SANKO MARU.
8 May 1939:
Completed and registered at Dairen, Manchuria (now Dalian, northern China).
3 December 1940:
Requisitioned by the IJN.
16 December 1940:
Registered in the IJN as an auxiliary collier/oiler attached to the Kure Naval District with Kure as homeport under Navy’s instruction No. 980.
E December 1940:
Assigned to Vice Admiral (later Admiral) Takasu Shiro’s (35) 4th Fleet as an auxiliary collier/oiler (Ko) category. 
15 January 1941:
Captain Suzuki Kozo (36) is appointed supervisor.
22 January 1941:
E January ~ February 1941:
Calls at Saipan, Marianas and Palau, Western Carolines.
28 February 1941:
Arrives at Yokosuka.
16 March 1941:
E March ~ May 1941:
Calls at Ponape, Eastern Carolines ~ Truk, Central Carolines and Saipan.
25 May 1941:
Arrives at Yokosuka. Departs later.
9 June 1941:
E 16 June ~ 16 July 1941:
Operates in the South Seas (Japanese mandated islands).
25 July 1941:
Arrives at Osaka.
11 August 1941:
Captain Suzuki is relieved by Captain Shimomura Keisaburo (33).
7 September 1941:
E 14 ~ 21 September 1941:
Operates in the South Seas.
29 September 1941:
Arrives at Yokosuka. Transfers later to Tsurumi near Yokohama.
2 October 1941:
Begins conversion to military duty at Asano Dock K.K. shipyard.
30 October 1941:
The conversion is completed.
6 December 1941:
Assigned to transport personnel and troop supplies under Yokosuka Naval District instruction No. 14.
28 December 1941:
After unloading cargo at Truk, assigned to load phosphorus ore at Saipan and then to sail to Yokohama under secret telegram No. 95.
21 January 1942:
Arrives at Yokosuka.
28 January 1942:
Ends troop and supply transport to the South Seas bases under Yokosuka Naval District instruction No. 45.
Assigned to Vice Admiral (later Admiral) Inoue Shiyegoshi’s (37) 4th Fleet as an auxiliary collier/oiler (Ko) category. 
Assigned to ammunition transport mission under secret telegram No. 139.
7 February 1942:
Departs Yokosuka with IJN requisitioned cargo ship (B-AK) IWAKI MARU.
E 17 February 1942:
Arrives at Rabaul, New Britain.
11 ~ 12 March 1942:
Coals auxiliary gunboat NIKKAI MARU.
19 ~ 20 March 1942:
Comes alongside and coals auxiliary gunboat SEIKAI MARU.
E March 1942:
16 April 1942:
Arrives at Yokosuka.
1 May 1942:
Captain Shimomura is relieved by Captain (Rear Admiral posthumously) Yamagata Shosuke (34).
5 May 1942:
At 1700, departs Yokosuka in convoy with IJA transport YAMASHIRO MARU escorted by auxiliary gunboat CHOUN MARU.
12 May 1942:
At 0900, YAMASHIRO MARU is detached for Saipan.
17 May 1942:
At 1050, arrives at Truk. Auxiliary merchant cruiser NOSHIRO MARU has met the convoy en route but then apparently detached to meet tanker TONAN MARU No. 2.
22 May 1942:
At 1500, departs Truk escorted by auxiliary merchant cruiser NOSHIRO MARU. At 2200, LtCdr (later Cdr ) Joseph H. Willingham's (USNA '26) USS TAUTOG (SS-199) fires one torpedo and heavily damages SANKO MARU at 06-10N, 150-30E. The auxiliary collier/oiler reverses course to Truk.
23 May 1942:
At 1320, arrives back at Truk for emergency repairs.
10 July 1942:
Captain Yamagata disembarks and is assigned directly to the Yokosuka Naval District.
14 July 1942:
Still under repairs at Truk. Assigned to Vice Admiral Mikawa Gunichi’s (38) 8th Fleet.
8 October 1943:
At 0400, departs Truk for Saipan in convoy No. 4008 also consisting of auxiliary transport CHOAN MARU No. 2 GO, IJN requisitioned cargo ships (B-AK) TSUNESHIMA and CHIYO MARUs with cable layer escort HATSUSHIMA and subchaser CH-12 as escorts. The convoy sails at 8.5 knots.
9 October 1943:
At 0515, the two escorts are detached.
E 10 October 1943:
Arrives at Saipan, Marianas.
11 October 1943:
Departs Saipan for Tateyama still in convoy No. 4008 with the same ships joined by auxiliary transport MUKO MARU.
13 October 1943:
18 October 1943:
The convoy is joined by IJN requisitioned cargo ships (B-AK) MANJU and TATEBE MARUs and IJA transport TAIAN MARU escorted by kaibokan FUKUE, auxiliary minelayer CHOAN MARU and auxiliary subchaser TAKUNAN MARU No. 10.
The merged convoy arrives at Tateyama, Chiba Prefecture.
19 October 1943:
Departs Tateyama and arrives at Yokosuka later that day.
1 January 1944:
Rerated auxiliary collier/oiler (Otsu) category. 
16 January 1944:
25 January 1944:
At 1800, departs Moji in convoy O-510 also consisting of auxiliary transport KIZUGAWA MARU towing midget sub HA-52, and IJA transports MITO, MACASSAR, YAKUMO, HINODE, KIBI, HASSHU, TASMANIA MARUs and SHINTO MARU No. 1 escorted by destroyer HARUKAZE, minesweeper W-17 and auxiliary subchaser TAMA MARU No. 7.
E 27 January 1944:
At 28N, TAMA MARU No. 7 is detached.
5 February 1944:
Arrives at Palau.
12 February 1944:
Departs Palau for Rabaul in convoy SO-903 towing midget submarine HA-52, also consisting of IJA transport SHINTO MARU No. 1 and civilian cargo ship (C-AK) TATSUKIKU MARU escorted by subchasers CH-22 and CH-39 and auxiliary subchaser Cha-16. Near Mussau Island, SANKO MARU and CH-39 are detached for Kavieng, New Ireland.
16 February 1944:
Off Three Island Harbor, New Hanover, Bismarck Archipelago. The convoy is attacked by nine Fifth Air Force B-25 "Mitchell" medium-bombers of the 500th ‘Rough Raiders’ Bomb Squadron of the 345 Bomb Group. The B-25s bomb, strafe and sink CH-39 (casualties unknown) and SANKO MARU (14 crewmen KIA) and damage the midget.
That same afternoon, B-25s of the 499th 'Bats Outta Hell' Bomb Squadron of the 345 Bomb Group find CH-39 sunk by the stern on a reef and abandoned. The 499th Bomb Squadron finishes her off with thirteen bombs that explode her magazine and boiler and reduce CH-39 to a shattered hulk. They also bomb and strafe the midget submarine on the surface and claim a sinking.
17 February 1944:
B-25s of the 500th Bomb Squadron return to the scene again and find the midget submarine still on the surface. They again bomb and strafe the midget and also claim a sinking. 
30 April 1944:
Removed from the Navy’s list under instruction No. 606.
 Not to be confused with Army transport No. 394 (4,958 GRT, ’37) or civilian cargo ship (C-AK) (630 GRT, ’19).
 There were two categories of Kyutanyusen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.
 Japanese sources claim the midget submarine's crew scuttled her after the B-25 attacks.
Thanks go to Gengoro S. Toda of Japan.
- Gilbert Casse and Peter Cundall.
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