Wartime History
Loaded aboard Chiyoda and transported to Shortland.

On November 2, 1942 at Shortland HA-11 was secured to the deck of I-20 while other midget subs were loaded aboard I-16 and I-24 at Shortland. Loading by November 5, 1942 the three submarines departed that evening under the command of Captain Ota Nobunosuke to patrol Indispensable Strait.

Sinking History
On November 7, 1942 at 5:20am Japanese submarine I-20 launches HA-11 four miles north of Cape Esperance off Guadalcanal. Aboard is commander Lt(jg) Nobuharu Kunihiro and and crew member PO1C Goro Inoue.

At 4:30am, this midget submarine begins reconnoiter the Lunga anchorage for targets. At 7:00am spots a destroyer and dives to 66' depth, changes course then at 7:25am resurfaces and spots two destroyers unloading supplies and fires one torpedo from 1,300 yards at the nearest target and dives to 100'.

Meanwhile at 7:27am USS Lansdowne DD-486 spotted a periscope and makes a sharp turn as the torpedo fired passes the stern but instead hits USS Majaba AG-43 that is damaged, beached and later salvaged. Afterwards, USS Lansdowne DD-486 and USS Lardner DD-487 search for the submarine. At 7:36am USS Lansdowne makes sonar contact and at 7:41 drops eleven depth charges then at 7:48 another eleven but the midget submarine escapes undamaged.

At 8:50am, commander Kunihiro notes his gyrocompass is malfunctioning then takes a course of 270°. At 11:00am surfaces 5,500 yards off Savo Island then dives on a course bound for Cape Esperance. At noon, changes course for Marovovo but at 12:45pm two aircraft are spotted and the submarine dives to 100'. At 1:45 the gyrocompass fails and the submarine surfaces. At 2:30pm run aground at Marovovo on Guadalcanal. Afterwards, the crew destroy secret materials then scuttled the submarine.

Fates of the Crew
Both crew swim ashore and link up with Japanese forces. They are the first midget submarine crew to survive a midget submarine mission.

Shipwreck
This submarine was abandoned at Marovovo on Guadalcanal. During 1994, the wreckage was identified by Ewan Stevenson and remains in situ.

Ewan Stevenson adds:
“26 July 1994: the author went back and found Kohyoteki 11 still there and in good condition. At this time, Kohyoteki 11 was in similar orientation, and the author is standing on the shallowest part of it. This significant archaeological site is extremely vulnerable to damage from salvagers or looting. It is fully protected under the Protection of Wrecks and War Relics Act 1980. It should remain in situ for as long as possible to prevent catastrophic deterioration. Ideally, at some point in the future, it may be recovered whole, but conservation and the costly funding to do it, must be in place prior to recovery. Perhaps recovery to Japan would be the best possible outcome to save this historic relic”.

References
Other sources list the captain as Lt(jg) Shinji Kunihiro
Combined Fleet - Midget Submarines in the Solomon Islands 1942
Archaehistoria - Kohyoteki 11 Submarine by Ewan Stevenson
Thanks to Ewan Stevenson and Peter Flahavin for additional information

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Last Updated
November 19, 2021