World War II Database

Contributor: David Stubblebine

This article refers to the entire Kaiten-class; it is not about an individual vessel.

ww2dbaseThe Kaiten were truly human guided torpedoes. Many authors do not include the Kaiten as a midget submarine since it is more of a person going on a torpedo ride; but they were machines whose design included transporting a person under the water and they fit the midget sub definition otherwise.

ww2dbaseKaitens were the first Japanese "Special Attack" weapons, vehicles whose use involved the certain death of the crew, though their first successful use followed the Kamikaze aircraft by about a month. Proposals for human torpedoes were made in 1943 and were approved in early 1944, initially with provision for the survival of the operator. However, the extreme peril facing Japan after the loss of the Marianas in June 1944 led to acceptance of the pilot's death as an inevitable consequence of Kaiten use.

ww2dbaseThe initial Kaiten Type 1 was converted from a 24-inch Type 93 torpedo. A new 39-inch forward section containing the warhead, additional fuel, oxygen tanks, and the pilot's compartment was grafted to the torpedo's middle and after sections, producing an overall length of just over 48 feet. Speed could be varied from 12 knots, giving a range of some 85,000 yards, to 30 knots and a range of about 25,000 yards. For guidance, the pilot had a short periscope. The Kaiten's immense 3,400-pound explosive warhead, more than three times the size of the Type 93 torpedo's original warhead, was capable of producing catastrophic damage in the target ship. Over 300 Type 1 Kaitens were produced in 1944-45; but only two are known to have been used to successfully sink enemy vessels.

ww2dbaseLarger Kaiten Type 2 and Type 4 had hulls about 4.5 feet in diameter and 55 feet long. The warhead was as large or larger than that of the Type 1 and performance was better. The Type 2 was not built in any quantity but some 50 of the less-ambitious Type 4's were reportedly built in 1945. There was also an experimental Type 3 of similar size to the Types 2 & 4 and a Type 10. Only the Type 1 was deployed operationally, however.

ww2dbaseOperational Uses

ww2dbaseOn 20 November 1944, five submarine-launched Kaitens penetrated the US anchorage at Ulithi in the Caroline Islands. Only one had any success, however, sinking the fleet oiler USS Mississinewa amidst pillars of thick black smoke that could be seen throughout the fleet. Eight months later on 24 July 1945, east of the Philippines, another Kaiten sunk the Buckley-class destroyer escort USS Underhill. These two incidents are the only confirmed successful Kaiten attacks, although some Japanese sources list higher numbers.

Kaiten-class Midget Submarine Interactive Map

Photographs

Kaiten-class Midget Submarine Operational Timeline

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1.  Alan Chanter says:
5 Feb 2013 06:51:04 AM

There is a desputed suggestion that the cruiser Indianapolis, which was returning to Leyte from Guam after delivering key components of the atomic bombs that were dropped on Japan, may also have been sunk by a Kaiten.

2.  David Stubblebine says:
5 Feb 2013 05:28:27 PM

I must admit that I was only able to make a preliminary check on this idea but what I found was this: The sources suggesting the Indianapolis may have been sunk by a Kaiten seem to be intentionally vague about it. The commander of the submarine that sunk the cruiser, Mochitsura Hashimoto, has been extremely clear and consistent on this point – he fired conventional torpedoes at Indianapolis and he says three of them struck the cruiser (the US version usually says two but it matters little). After the war, Hashimoto testified at the US Navy Court Martial of the Indianapolis captain and described the attack in excruciating, almost absurd, detail; he described it as a conventional torpedo attack. In Hashimoto’s book, Sunk!, he chronicles his submarine career in great detail from Pearl Harbor to the end of the war. In the book, he is never reluctant to describe the occasions when he did launch Kaitens and there is no reason to believe he would say he fired torpedoes at Indianapolis when he really launched Kaitens. If there really is a chance Indianapolis was sunk by a Kaiten, the people who think so need to bring forth some better evidence. So far, I don’t think it is so.