Commander Ensign Yokoyama (KIA)
Crew Petty Officer 2nd Class Tei Uyeda (KIA)
Sunk December 7, 1941
Built in Kure during 1938. Delivered to the Imperial Japanese Navy (IJN) as HA-20 Type A Midget Submarine. Known to the U. S. Navy as "Midget A", the 1st midget sumarine encountered during the attack on Pearl
On December 7, 1941 one of five midget subs attached to five I-class "mother"
submarines (I-16, I-18, I-20, I-22 and I-24) to be launched 5-6 hours
before the aerial attack, within a few miles off Pearl
Harbor to penetrate the harbor. Submerged, the midget submarines would navigate counterclockwise around Ford Island, fire their torpedoes then rendezvous with the submarines seven miles west
of Lanai Island.
On December 7, 1941 at 2:57am Japanese submarine I-20 launches this midget submarine. At 3:20am the periscope of this midget submarine was spotted by USS Condor AMc-14 two miles off the entrance to Pearl
Harbor and by 3:57am notifies USS Ward DD-139 using blinker signals. At 4:08am, the destroyer begins searching for the submarine but finds nothing.
At 6:30am the submarine's was spotted by lookouts aboard USS Antares (AG-10) towing a target raft as the vessel approaches the outer gate to Pearl
Harbor. Above, PBY Catalina 14-P-1 piloted by Ensign William P. Tanner from VP-14 drops smoke markers on the target.
At 6:37am the periscope is spotted by USS Ward DD-139. At 6:45am the destroyer opens fire with her 4" guns. The first shot misses and the second shot fired from 50 yards hits the conning tower at the waterline and overruns the submarine, causing it to wallow in her wake as she drops four depth charges and reports: "We have attacked fired upon and dropped depth charges upon submarine operating in defensive sea area". Above, the PBY Catalina also release depth charges. The submarine is reported at 6:45am and 6:53am and confirmed sunk at 6:55am, an hour before the start of the aerial attack on Pearl Harbor and Oahu.
During 1988 the US Navy (USN) and
Service (NPS) conducted a submerged cultural resources survey underwater in Pearl
Harbor, but failed to locate this midget submarine.
On August 28, 2002 Hawaii Undersea Research
Laboratory (HURL) discovered the wreck during their third routine training dive in
submersibles Pisces IV and V. The submarine was perfectly preserved at a depth of
1,200' roughly 3-4 miles off Pearl
The conning tower has a hole from the 4" shell that hit the submarine causing it to sink. The hatch is closed indicating both crew members went down with the submarine. The exact location is kept secret to protect the submarine.
On March 6, 1942, the midget submarine crews of all the Pearl Harbor attack (except Ensign Sakamaki who was taken prisoner) were posthumously promoted two ranks.
The crews are also memorialized at the Nine War Gods Monument at Suga Park, Mitsukue Bay, Ehime Prefecture.
Other sources report the crew as Ensign Hiroo Akira with PO2C Katayama Yoshio.
Combined Fleet - Midget Submarines at Pearl Harbor, Hawaii 1941
National Geographic Pearl Harbor Timeline - Remembering Pearl Harbor 0342, 0645, 0653, 0715
HURL Search for the World War II Japanese Midget Submarine Sunk off Pearl Harbor
HURL Images and video clips of the Midget Submarine
HURL New Analysis of the Cannon Hole, December19, 2003 [PDF file]
Star Bulletin "Ownership and control of midget sub uncertain" September 1, 2002
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May 20, 2019