(TSUBAME by Takeshi Yuki)
IJN Minelayer SOKUTEN:
Tabular Record of Movement
© 2005-2015 Bob Hackett, Sander Kingsepp and Peter Cundall
24 June 1937:
Yokohama. Laid down at the Mitsubishi Heavy Industries' shipyard.
27 April 1938:
28 December 1938:
Completed and registered in the Sasebo Naval District.
26 January 1942:
At 0530 SOKUTEN departs from outside Takao port.
29 January 1942:
At 0730 SE of Taichow Liehtao. Auxiliary gunboat SHINKO MARU No.1 GO joins a convoy heading north consisting of unidentified merchant ships escorted by destroyer HASU. Later that day at 1630, minelayer SOKUTEN also joins the convoy.
30 January 1942:
Off Taichow Liehtao. SHINKO MARU No.1 GO is detached.
28 March 1942:
At 0800, SOKUTEN and auxiliary gunboat CHOHAKUSAN MARU depart Mako for Camranh Bay escorting a convoy consisting of FUKKAI, KOCHI, TAIKAI, RYUZAN, TETSUYO, TEIKAI (ex German FULDA), SAMARANG and PENANG MARUs and YOSHIDA MARU No. 1.
1 April 1942:
Arrives at Camranh Bay, Indochina.
10 June 1942:
SOKUTEN and minelayer HOKO depart Mako escorting convoy No. 221 consisting of HAKKAI MARU and four unidentified merchant ships.
15 June 1942:
Arrives at Mutsure.
1 July 1942:
SOKUTEN and destroyer SATSUKI depart Mako escorting convoy No. 228 consisting of five unidentified merchant ships.
6 July 1942:
Arrives at Mutsure.
23 August 1942:
SOKUTEN and auxiliary gunboat HUASHAN (KAZAN) MARU depart Mako escorting convoy No. 330 consisting of tanker OGURA MARU No. 2, NICHIRAN and KOGANE MARUs and nine unidentified merchant ships.
30 August 1942:
Arrives at St Jacques.
7 March 1943:
At 2250 TANGO MARU reports a torpedo attack in 26-50N 122-37E.
8 March 1943:
At 0825 auxiliary gunboat CHOHAKUSAN MARU followed at 0900 by SOKUTEN and auxiliary patrol boats NITTO MARU No. 21, NITTO MARU No. 22 and YOKAI MARU depart port [Kirun?] to intercept and destroy the submarine and protect inbound ship OYO MARU.
9 March 1943:
At 0755 an enemy submarine is detected and depth charged in position 25-51N 123-34E. Attacks continue throughout much of the day until 1516 and the submarine is claimed as sunk.
10 March 1943:
At 1245 arrives at Kirun.
19 March 1943:
Off Keelung, Formosa. Alerted by a codebreaker’s “Ultra” signal, LtCdr (later Vice Admiral) Vernon L. Lowrance’s (USNA ’30) USS KINGFISH (SS-234) intercepts troop transport TAKACHIHO MARU enroute to the Philippines escorted by SOKUTEN. At about 0900, USS KINGFISH torpedoes and sinks TAKACHIHO MARU with passengers and 2,614-tons of general cargo, at 25-50N, 122-30E. Only one lifeboat is seen to get away. 741 out of 917 passengers and 98 out of 176 crewmen are killed.
Following the sinking of TAKACHIHO MARU, the IJN directs several ASW units to the area N and NE of Taiwan, supported by three Mitsubishi G3M “Nell” patrol bombers from the Shinchiku Naval Air Group.
23 March 1943:
At about 0430, SOKUTEN, attached to the Mako Guard District, spots a surfaced submarine. SOKUTEN subjects USS KINGFISH to a severe depth charge attack. A squealing propeller shaft on the submarine aids the minelayer in locating USS KINGFISH. Lowrance orders secret codes and material burned in preparation to abandoning ship.
The Mako Guard District HQ next directs auxiliary gunboat CHOHAKUSAN MARU, auxiliary subchasers NITTO MARU No. 21 and No. 22 and YOBAI MARU to the same position. OYO MARU is next to attack, followed by CHOHAKUSAN MARU. USS KINGFISH briefly surfaces, revealing six meters of her bow before disappearing again.
After 1326, a substantial amount of diesel oil is sighted. The six ASW vessels drop 41 depth charges, the majority by SOKUTEN and CHOHAKUSAN MARU. The last string of depth charges smashes in the main induction piping allowing a huge bubble to escape to the surface. This apparently causes SOKUTEN’s captain to think the submarine had been sunk.
24 March 1943:
The chase continues until the morning over a 24 nm long distance. After a 16-hour ordeal, USS KINGFISH cautiously surfaces, clears the area and heads for Pearl Harbor.
1 May 1943:
At 1225 arrives at Rabaul.
4 May 1943:
At 1300 departs Rabaul on an escort mission.
7 May 1943:
At 1700 arrives back at Rabaul.
19 May 1943:
At 1500 departs Rabaul on patrol.
23 May 1943:
At 0900 arrives back at Rabaul.
27 May 1943:
At 0415 departs Rabaul for unknown reasons returning at 0950.
5 June 1943:
At 1310 departs Rabaul on an escort mission.
7 June 1943:
At 0440 arrives back at Rabaul. Soon after at 0630 departs Rabaul again on a further escort mission.
13 June 1943:
At 1000 arrives at Rabaul.
17 June 1943:
At 1600 departs Rabaul on an escort mission.
19 June 1943:
At 1700 arrives at Rabaul.
20 June 1943:
At 1300 departs Rabaul on an escort mission.
29 June 1943:
At 0558 arrives at Rabaul.
1 August 1943:
At 0550 arrives at Rabaul.
2 August 1943:
At 1200 departs Rabaul on escort mission.
19 August 1943:
At 1255 arrives back at Rabaul.
3 September 1943:
Departs Rabaul in convoy 2032 consisting of KIYOSUMI and TOKYO MARUs also escorted by submarine chaser CH-28 and minesweeper W-4. At some point into the journey SOKUTEN is apparently detached.
6 September 1943:
At 0930, W-4 and CH-28 arrive at Kimishima Channel, Truk escorting the convoy.
1 March 1944:
Reassigned to 5th Base Force at the Central Pacific Area Fleet.
12 March 1944:
At 0400, SOKUTEN and minelayer KYOSAI depart Tokyo with light cruiser TATSUTA, destroyers NOWAKI, ASAKAZE, YUNAGI and UZUKI, kaibokan HIRADO, and minesweeper W-20 escorting outbound convoy "Higashi Matsu No.2" consisting of TAKAOKA, HIBI, TAJIMA, MIHO, AWA, DAITEN, RYUKA, TAMAHOKO, KOKUYO, TSUSHIMA and ATLANTIC MARUs and SHINSEI MARU No. 1.
13 March 1944:
40 miles NNE of Hachijo-jima. At 0310, LtCdr Malcom E. Garrison's (USNA ’32) new USS SAND LANCE (SS-381) sets up and fires four stern torpedoes at the convoy. Two hit and sink TATSUTA taking down 26 sailors, at 32-52N 139-12E. The other two hit and sink transport KOKUYO MARU carrying 1,029 troops and AA equipment. 43 of the crewmen and 679 troops on board are killed. SAND LANCE undergoes an 18-hour attack by the escorts. USS SAND LANCE, a thick-skinned USS BALAO-class, dives to 550-feet and escapes 105 depth charges.
19 March 1944:
At 1400 arrives at Saipan.
Arrives at Palau. Engages in mine laying.
9 April 1944:
At 1625, LtCdr (later Captain) Slade D. Cutter’s (USNA ’35) USS SEAHORSE (SS-304) attacks part of convoy “Higashi-Matsu” No. 4. Cutter torpedoes and hits cargo ship MIMASAKA (BISAKU) MARU that is headed for Guam. The ship is carrying 1146 Naval men and their accompanying luggage, a total of 1,437 tons. Seven men from the Naval party, one armed guard and 10 crewmen are killed.
At 1830, USN codebreakers intercept and decrypt a message that reads: “ [DD] IKAZUCHI and SOKUTEN are scheduled to arrive at the scene of BISAKU MARU disaster at 2100.”
10 April 1944:
At about 0100, MIMASAKA (BISAKU) MARU sinks.
18 July 1944:
SOKUTEN is assigned to the Fourth Fleet's 5th Base Force.
20 July 1944:
Reassigned to the Southwest Area Fleet's Third Expeditionary Fleet's 30th Base Force.
25 July 1944:
SOKUTEN departs Palau to carry out minelaying in the area of Ulithi Atoll, western Carolines. At about 1545 she is engaged by four Grumman F6F “Hellcat” fighters from VF51 of Vice Admiral (later Admiral) Marc A. Mitscher's (USNA ’10) Task Force 58’s carrier USS SAN JACINTO (CVL-30) about 30 miles NE of Babelthuap, Palau.
SOKUTEN, is escorted by an Aichi E13A1 Jake floatplane. One Hellcat attacks the Jake and shoots it down. SOKUTEN is misidentified by the F6F pilots as a FUBUKI-class destroyer. The other Hellcats strafe SOKUTEN and cause her load of mines to explode. She sinks at 07-20N, 134-27E. 
10 September 1944:
Removed from the Navy List.
 Photographs of the sinking of SOKUTEN were taken by Ensign George H. W. Bush's Grumman TBF "Avenger" torpedo-bomber of Torpedo Squadron (VT-51).
 Historian George Kernahan of the UK notes that altho SOKUTEN was sunk by Hellcats several sources including Jentschura give the location as 07-20N, 134-27E, which corresponds to Malakal Harbour in the central Palaus. However, Kernahan also notes that the attack took place in the open sea north of Babelthuap. The ship (and accompanying Jake) was sighted 10 miles north of Kayangel (08-04N 13442E) and the location of the Jake shootdown is given as 08-35N, 134-30E. He suggests that this is the likely location of the minelayer's demise.
Thanks go to the late John Whitman of the USA for info on CNO intercepts of Japanese messages and to Gilbert Casse of France for his contribution to revisions.
-Bob Hackett, Sander Kingsepp and Peter Cundall.