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Ship ClassI-400-class Submarine
BuilderSasebo Naval Arsenal
Laid Down20 Oct 1943
Commissioned24 Jul 1945
Sunk1 Apr 1946
Displacement5,223 tons standard; 6,560 tons submerged
Length400 feet
Beam39 feet
Draft23 feet
MachineryFour diesel engines totalling 7,700hp, electric motors totalling 2,400hp
Speed18 knots
Range37,500nm at 14 knots
Armament8x533mm forward torpedo tubes, 20x533mm Type 95 torpedoes, 1x140mm gun, 3x25mm machine guns, 1x25mm machine gun
Submerged Speed6.5 knots


ww2dbaseSubmarine I-402, along with her sister submarines, were the largest submarines in the world until 1965. Built at Sasebo, Japan seven months after the launch of the first ship in the class, her plans were changed mid-way through the construction, converting her from a submarine aircraft carrier to an aviation fuel tanker. After her completion, she joined Submarine Squadron 1 of the Sixth Fleet with Commander Otoji Nakamura in command. She remained in port at Kure, Japan in late Jul 1945 and did not join her sister ships in the abortive attack on Ulithi in the Caroline Islands. At 1040 on 11 Aug, while at Kure, she was attacked by two P-51D Mustang fighters; the strafing punctured the main fuel tanks and wounded two sailors.

ww2dbaseThe Americans never learned of the existence of the I-400-class submarines until their crews surrendered. I-402 was studied by the United States Navy at Sasebo, Japan between Oct 1945 and Apr 1946. As the Russians planned a mission to Sasebo to study captured Japanese submarines, the US Navy decided to launch Operation Road's End on 1 Apr 1946, which used I-402 as a target ship for destroyer USS Larson. She was later scuttled off Nagasaki, Japan near the Goto Islands.

ww2dbaseSources: Nihon Kaigun, Wikipedia.

Last Major Revision: Oct 2008

Submarine I-402 Interactive Map

I-402 Operational Timeline

20 Oct 1943 The keel of I-402 was laid down at Sasebo Naval Arsenal, Japan.
24 Jul 1945 I-402 was commissioned into service.
11 Aug 1945 I-402 suffered a punctured fuel tank during an American air attack on Kure, Japan.
1 Apr 1946 I-402 was scuttled 60 miles off Sasebo, Japan at 1300 hours.

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Visitor Submitted Comments

1. phantomworks says:
14 Nov 2011 05:55:37 AM

Although the Japanese had very good submarines,some even better than the allies or the German U-boats.The Japanese never fully utilized them in dedicated attack role.Some were used that way and inflicted considerable damage to Allied fleets,but many Japanese subs were used as transports,recon,and underwater seaplane carriers this shows how resourceful the Japanese were with their subs.However the Japanese subs were treated as a "Jack of all trades and a master of none".Had more Japanese subs been used like attack subs like German U-boats they would have sunk more Allied ships.The Germans use of their U-boats resulted in them sinking more Allied ships earlier in the war,but as the Allies developed better countermeasures,the U-boats were unable to overcome them and began to lose their advantage as well as the war.The German U-boats were a master of the "wolfpack" attack on enemy shipping but were not flexible enough to change tactics when the tide turned against them. That resulted in a 70% attrition rate for U-boats and crews in the war.

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