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Mopping-up the Japanese Midget-Submarines

Posted by GP

Japanese type-A midget sub salvaged near Pearl Harbor

By definition, a midget submarine is less than 150 tons, has a crew of no more than eight, has no on-board living accommodation, and operates in conjunction with a mother ship to provide the living accommodations and other support. The Japanese Navy built at least 800 midgets in 7 classes, but only a fraction had any noticeable impact on the war. Their intended purpose initially was to be deployed in front of enemy fleets, but their actual use would be in harbor attacks and coastal defense.

Japanese type-D sub sitting at the Yokosuka Naval Base, Sept. 1945

The Japanese midget subs were not named but were numbered with “Ha” numbers (e.g., Ha-19). These numbers were not displayed on the exterior and operationally the midgets were referred to according to the numbers of their mother ships. Thus, when I-24 launched Ha-19, the midget was known as “I-24tou” (designated “M24” in some texts). The “Ha” numbers were not unique either; some Type D’s were numbered Ha-101 through Ha-109.

In mid-1944, with coastal defense requirements becoming urgent, the Japanese Navy developed the Koryu Tei Gata Type D. More than just another improved version of the Type A, this was a new design. They were the largest of Japan’s midgets, displacing about 60 tons, 86 feet (26 meters) in length, with a five-man crew, featuring a more powerful diesel engine, and had improved operating endurance. Koryu’s armament consisted of two muzzle-loaded 17.7-inch torpedoes. As with the earlier types, individual boats had alpha-numeric names in the “Ha” series beginning with Ha-101.

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Some 115 units had been completed when Japan capitulated in August 1945. At the end of the war, Allied Occupation forces found hundreds of midget submarines built and building in Japan, including large numbers of the “Koryu” type; nearly 500 more were under construction. Some of these submarines intended for training pilots for Kaiten type manned torpedoes, had an enlarged conning tower and two periscopes.

Kaiten design

Kaiten submarines were designed to be launched from the deck of a submarine or surface ship, or from coastal installations as a coastal defense weapon. The cruiser, IJN Kitakami, was equipped to launch Kaiten and took part in sea launch trials of Type 1s. In addition, several destroyers of the Matsu class were also adapted to launch the weapon.
In practice, only the Type 1 craft, using the submarine delivery method, were ever used in combat. Specially equipped submarines carried two to six Kaiten, depending on their class.

After the end of the conflict, several of Japan’s most innovative and advanced submarines were sent to Hawaii for inspection in “Operation Road’s End” (I-400, I-401, I-201, and I-203) before being scuttled by the U.S. Navy in 1946 when the Soviet Union demanded access to the IJN submarines.

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Don’t Forget :

May is Military Appreciation Month, for this coming week….

May 8, 2019 – VE (Victory in Europe) Day

(Celebrated May 7 in commonwealth countries)

A day which marks the anniversary of the Allies’ victory in Europe during World War II

on May 8, 1945. Learn more…

May 10, 2019 – Military Spouse Appreciation Day

A day set aside to acknowledge the contributions and sacrifices of the spouses of

the U.S. Armed Forces. Learn more…

LINK – Practical insights in caring for a military home front family

May 12, 2018 – Mother’s Day

LINK – Organizations that support deployed military personnel on Mother’s Day

LINK – Coloring page for military children

May 13, 2019 – Children of Fallen Patriots Day

A day to honor the families our Fallen Heroes have left behind – especially their children. It’s a reminder to the community that we have an obligation to support the families of our Fallen Patriots. Learn more…

SHAKE A VETERAN’S HAND TODAY!

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