KUSENTEI!

© 2005-2009 Bob Hackett, Sander Kingsepp and Peter Cundall

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26 August 1940:
Osaka. Laid down as CH-182 at the Sakurajima Ironworks.

23 December 1940:
Launched and renumbered CH-15.

31 March 1941:
Completed and registered in the Yokosuka Naval District.

7 December 1941: Operation "M" - The Invasion of the Northern Philippines:
CH-15 is in Rear Admiral (later Vice Admiral) Kubo Kyuji’s (38) (former CO of KAGA) 1st Base Force of Vice Admiral Takahashi Ibo’s (35)(former CO of YAMASHIRO) Third Fleet. CH-15 is attached to Takahashi's Philippines Seizure Force in Cdr Nakamura's SubChasDiv 2 with CH-13 and CH-14. At 1630, departs Mako, Pescadores.

10 December 1941:
Beginning at 0550, participates in the landings at Aparri, Philippines.

24 December 1941:
With the Lamon Bay, Philippines invasion force.

23 January 1942:
With the Balikpapan, Borneo invasion force.

6 February 1942: The Invasion of Makassar, Celebes:
SubChasDiv 2’s CH-13, CH-14 and CH-15 depart Staring Bay with the Makassar Occupation Force consisting of six troop transports carrying Captain (later Vice Admiral) Mori Kunizo’s Sasebo Combined Special Naval Landing Force (SNLF) escorted by light cruiser NAGARA, DesDiv 8’s ASASHIO, MICHISHIO, ARASHIO and OSHIO, DesDiv 15’s HAYASHIO, KUROSHIO, OYASHIO and DesDiv 21’s WAKABA, NATSUSHIO and NENOHI and MineSweepDiv 21’s W-7 and W-8.

10 March 1942:
Assigned to Vice Admiral Takahashi's Southwest Area Fleet's newly formed Second Southern Expeditionary Fleet in Special Base Force 21.

15 May 1942:
Reassigned to the Yokosuka Guard Unit. Escorts convoys departing alternately from Shimoda and Nagaura bases.

20 July 1942:
Reassigned to SubChasDiv 5 in Vice Admiral Hosagaya Boshiro's (former CO of MUTSU) Fifth Fleet based at Ominato, Northern Honshu.

August 1942:
Arrives at Kiska, Aleutians.

20 November 1942:
Reassigned to the Yokosuka Guard Unit for the second time. Escorts convoys to Owase.

May 1943:
Reassigned to the Fifth Fleet for the second time. Escorts convoys to the Kuriles.

15 June 1943:
Reassigned to the Ominato Naval District patrol unit. Escorts convoys to the Hokkaido ports of Muroran and Wakkanai.

11 October 1943:
La Pérouse/Soya Strait, Northern Japan. After completing a successful patrol in which he probably sinks four ships, Cdr Dudley W. Morton’s USS WAHOO (SS-238) is exiting the Sea of Japan on the surface, but leaving a trail of oil from a previous encounter. At about 0830, the spotter for a 6-inch coast artillery battery on Soya Misaki promontory sights WAHOO and opens fire. Morton submerges and continues on course. The battery commander calls for air support.

About an hour later, an E13A1 "Jake" anti-submarine floatplane No. 19, out of Wakkanai, arrives. At 0920, the Jake detects a widening oil slick, then sees the conning tower of a submarine. The E13A1's pilot drops two bombs on WAHOO. Two more E13A1s of the same unit arrive and drop a total of six depth-charges. At 1145, the first floatplane directs CH-15 to the scene. At 1203, the submarine is located and CH-15 drops two series of nine and seven depth-charges. Among the debris thrown up by explosions is a metal object that resembles the propeller blade of a submarine. At 1218, CH-15 drops a single depth-charge, then is relieved by CH-43. At 1221, CH-43 drops six depth-charges. At 1330, auxiliary minesweeper Wa-18 arrives. As a result of these attacks, WAHOO is sunk with all hands at 45-13N, 141-56E. [1]

28 October 1943:
CH-15 departs Odomari for Ominato escorting a convoy consisting of NAGATA and EIHO MARUs.

29 October 1943:
At 0120, LtCdr Nicholas J. Nicholas' USS SALMON (SS-182) fires three torpedoes and gets two hits on NAGATA MARU, but both Mark XIV torpedoes are duds. A plane bombs SALMON without effect. CH-15 counterattacks and drops 11 depth-charges on SALMON, but Nicholas evades without damage. At sea, NAGATA MARU's crew repairs the holes punched in their ship's side and she continues on, stopping at two ports on Hokkaido.

At 0150, USN codebreakers intercept and decrypt a message from CH-15 that reads: “At 0130, received enemy submarine attack. Position ---- E, 45-32 N.”

16 November 1943:
Arrives at Ominato, Honshu. 23 May 1944: W-15 departs Naha for Kagoshima via Koniya with minelayers TSUBAME and NIIZAKI (part way only), auxiliary minesweeper HAKATA MARU No. 6, and auxiliary YUKO MARU escorting convoy NAKA-305 consisting of five unidentified merchant ships. 29 May 1944: W-15 departs Kagoshima for Keelung with minelayers NIIZAKI and TSUBAME, minesweeper, auxiliary minesweeper HAKATA MARU No. 6, auxiliary patrol boat RYUSEI MARU escorting convoy KATA-906 consisting of seven unidentified merchant ships. 2 June 1944: W-15 departs Naha for Kagoshima with minelayer TSUBAME, auxiliary patrol boats HOKOKU MARU No. 3 Go, CHIKUTO and RYUSEI MARUs escorting convoy NAKA-204 consisting of five unidentified merchant ships. 6 June 1944: W-15 departs Kagoshima for Keelung with minelayer TSUBAME, auxiliary minesweepers HAKATA MARU No. 6, BANSHU MARU No. 51, TOSHI MARU No. 7, SHIMPO MARU, auxiliary patrol boat CHOUN MARU No. 13 escorting convoy KATA-614 consisting of 15 unidentified merchant ships enroute to Keelung, some direct and some via Naha.

14 July 1944:
W-15 departs Manila wih minelayer KYOSAI escorting convoy MATA-24A consisting of one unidentified merchant ship.

17 July 1944:
Arrives at Takao.

27 August 1944:
At 0749, CH-15 and minesweeper W-23 depart Wakkanai, northern Hokkaido for the Kuriles escorting convoy KI-203 consisting of MISAKI MARU No. 2 and EISHIN and HAKUSHU MARUs and two unidentified Marus.

29 August 1944:
At 1440, the convoy arrives at Tennei, Kuriles.

6 September 1944:
W-15 departs Kagoshima for Naha with kaibokan CD-30, minelayer NUWAJIMA and TSUBAME auxiliary minesweepers KAIYO MARU No. 1 Go, TAKUNAN MARU No. 3, CHITOSE MARU, auxiliary patrol boat HOKOKU MARU No. 3 Go escorting convoy KANA-602 consisting of two unidentified merchant ships.

5 November 1944:
CH-15 departs Manila with subchasers CH-17, CH-23, CH-37 and CH-38 and kaibokan CD-18 and CD-26 escorting convoy MATA-31 consisting of seven unidentified merchant ships.

6 November 1944:
At 1055, an enemy submarine is sighted at 16-11N, 109-06E.

15 November 1944:
Arrives at Takao.

18 June 1945:
At 1400, CH-15 and three unidentified coast defense ships depart Kataoka Bay, Shimushu Island in the Kuriles for Ominato escorting the “RU” Convoy transporting aviation gasoline and consisting of HAKUAI and ZAOSAN MARU. At 1920, that same day the convoy is intercepted by three surfaced submarines. LtCdr Arthur C. House's USS APOGON (SS-308) fires 10 torpedoes from close range and sinks both HAKUAI and ZAOSAN MARUs. CH-15 rescues 192 survivors.

19 June 1945:
At 0117, USN codebreakers intercept and decrypt a message from CH-15 to an unidentified station that reads: “Pick up survivors of HAKUAI (Hiroi) MARU --.”

At 0700, CH-15 returns to Kataoka Bay and puts the survivors ashore.

15 August 1945:
Yokosuka. CH-15’s crew learns of the termination of the war.

30 November 1945:
Removed from the Navy List.

1 November 1946:
Appointed a special cargo ship in the Allied Repatriation Service, but is inactive because her machinery is out of commission.

23 April 1948:
CH-15 is sold for scrap.

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Authors' Note:
[1] Morton was posthumously awarded a fourth Navy Cross. He and WAHOO sank 19 cargo and transport ships for a total of 55,000 tons.

Thanks go to John Whitman of the USA for info on CNO intercepts of Japanese messages.

-Bob Hackett, Sander Kingsepp and Peter Cundall.

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