SENSUIKAN!

© 2001-2014 Bob Hackett & Sander Kingsepp
Revision 5

26 August 1943:
Laid down at Mitsubishi Kobe Yard as a a Type D1 transport submarine No. 5466. .

9 March 1944:
Launched and numbered I-366.

3 August 1944:
I-366 is completed, commissioned in the IJN and attached to the Yokosuka Naval District. LtCdr (Cdr, posthumously) Masata Keiji (62)(former CO of I-159) is the CO. Assigned to SubRon 11 for working-up in Kobe area, later proceeds to Kure.

Early September 1944:
Kure. After one of I-366's diesels breaks down, she undergoes engine repairs at Kure Navy Yard until early October. .

2 October 1944:
Reassigned to Rear Admiral Owada Noboru's (former CO of YAMASHIRO) SubRon 7, Sixth Fleet.

Early November 1944:
Proceeds to Yokosuka. .

3 December 1944:
At 1600, I-366 departs Yokosuka for Pagan Island, Marianas with 51-tons of food and ammunition. Soon after departure, I-366 is caught in a heavy storm and loses a number of rubber containers attached to her afterdeck filled with rice.

10 December 1944:
On the evening, while surfaced to charge batteries, I-366 detects an enemy aircraft and crash-dives to 130 feet. As a result of a malfunctioning valve the submarine drops to 290 feet and develops a leak through the periscope shaft.

14 December 1944:
In the evening, arrives at Pagan and unloads her cargo to Daihatsu barges. Departs Pagan four hours later with 49 passengers, including some IJAF pilots. Of more than ten wounded passengers, six die enroute home.

28 December 1944:
At 1000, I-366 arrives at Yokosuka with 43 passengers. During a refit she is fitted with a Type 13 air-search radar.

1 January 1945:
I-366 is in SubRon 7 with I-361, I-362, I-363, I-367, I-368, I-369, I-370 and I-371.

5 January 1945:
Lt Tokioka Takami (67)(former CO of RO-67) assumes command.

29 January 1945:
At 1300, departs Yokosuka for Truk carrying avgas and spares for the 141st Naval Air Group's Nakajima C6N1 Saiun ("Myrt") recce aircraft for a planned overflight of Ulithi anchorage. Soon after departure, I-366's crew finds that their short-wave radio mast cannot be retracted. Lt Tokioka decides to return to Yokosuka for repairs. After repairs are completed, I-366 departs that same evening and spends the night at Tateyama Bight.

10 February 1945:
At 0448, a lookout reports a cruiser on a southwesterly bearing.

12 February 1945:
Arrives at Truk and unloads some of her cargo, including 33 tons of fuel.

16 February 1945:
Arrives at Mereyon. Islet in the Woleai Atoll of the Carolines. After sunset, unloads 51-tons of food and ammunition to nine Daihatsu barges, embarks 42 passengers and departs. [1]

Late February 1945:
En route to Yokosuka Lt Tokioka sights an enemy convoy bound for Iwo Jima.

3 March 1945:
Returns to Yokosuka. SubRon 7 is deactivated. I-366's deck guns and Daihatsu landing craft fittings are removed and she is converted to carry five "kaiten" human-torpedoes. Unlike some of her sisters, I-366 is not fitted with conventional torpedo tubes.

20 March 1945:
SubRon 7 is deactivated. I-366 is reassigned to SubDiv 15.

1 April 1945: American Operation "Iceberg" - The Invasion of Okinawa:
Vice Admiral (later Admiral) Raymond A. Spruance's Fifth Fleet, including more than 40 aircraft carriers, 18 battleships, 200 destroyers and over 1,000 support ships surround Okinawa. LtGen Simon B. Buckner Jr's Tenth Army (7th, 77th, 96th Infantry, 1 st, 6th Marine divisions) makes amphibious landings and takes the island from LtGen Ushijima Mitsuru's 32nd Army.

2May 1945:
I-366 is ordered to depart on the 4th for Hikari (35-08N, 126-54 E) to load Kaiten and attack Allied shipping in the area between Okinawa and the Marianas. .

6 May 1945:
Around noon, I-366 is conducting kaiten launching exercises off Hikari prior to her departure with the "Shimbu” kaiten group the next day, she grazes a magnetic mine and her stern planes and propellers are damaged. A tug arrives from Hikari and takes the submarine in tow. She undergoes repairs at Kure Navy Yard, but cannot take part in the Shimbu mission with I-367.

June 1945:
I-366 undergoes installation of radar scheduled to be completed by 5 July. .

20 July 1945:
I-366 engages in Kaiten training operations..

1 August 1945: The Eighth Kaiten Mission:
I-366 is in the "Tamon" kaiten Group with I-47, I-53, I-58, I-363 and I-367. Departs Hirao for an area SE of Okinawa.

11 August 1945:
500 miles N of Palau. I-366 attacks a convoy. Lt Tokioka decides to launch all of his kaitens, but two are found defective. Tokioka launches three kaitens piloted by Lt (j.g.) Naruse Kenji, FPO1C Uenishi Norihide and FPO1C Sano Hajime from an extremely long distance. No hits are registered. In I-366's navigator’s opinion, the kaiten ran out of fuel enroute to their targets and their drivers suffocated.

Lt Tokioka claims three American transports sunk, but postwar analysis does not verify the claim.

15 August 1945:
I-366 is returning to base when she receives a signal that Emperor Hirohito (Showa) has broadcast a call for an end to hostilities.

18 August 1945:
Arrives at Kure.

September 1945:
Surrenders to Allied Forces.

October 1945:
Transferred from Kure to Sasebo.

30 November 1945:
Removed from the Navy List.

1 April 1946: Operation "Roads End":
I-366 is stripped of all usable equipment and material and towed from Sasebo to an area off Goto Retto by submarine tender USS NEREUS (AS-17)..

By 1339, the Japanese crew is evacuated. At 1350 the C-2 explosive charge in her stern compartment explodes and the submarine starts to settle down slowly. Her bow rises 15 feet above the water. Two minutes later another demolition charge goes off in the bow and I-366 blows up, hurling debris over a wide area. One of her torpedo tube doors misses the motor launch from NEREUS with I-366 's crewmembers in it by some 100 yards.

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Authors' Notes:
[1] According to some sources 43 passengers were taken aboard.

Special thanks go to Mr. Derek Waller of the UK for providing additional sources on Operation "Roads End."

Thanks go to Dr. Higuchi Tatsuhiro of Japan. Thanks for help with the COs in Rev 1 go to Steve Eckhardt of Australia. Thanks also go to John Whitman of the USA for info on CNO intercepts of Japanese messages.

– Bob Hackett & Sander Kingsepp

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