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  HA-22 Type A Midget Submarine (Midget B)
Type A
Kō-hyōteki kō-gata

46 Tons (surfaced)
47 Tons (submerged)
78.5' x 6' x 10.2'
2 x Type 97 torpedo
140kg scuttling charge

Commander  Lt. Naoji Iwasa (KIA)
Crew  PO1C Naokichi Sasaki (KIA)
Sunk  December 7, 1941 at 8:39am

Ship History
Built in Kure during 1938. Delivered to the Imperial Japanese Navy (IJN) as HA-22 Type A Midget Submarine. Known to the U. S. Navy as "Midget B", the 2nd midget sumarine encountered during the attack on Pearl Harbor.

Mission History
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 exit the area to rendezvous with their mother subs seven miles west of Lanai Island.

Sinking History
On December 7, 1941 at 1:10am, I-22 arrives to the launch point 9 miles off the entrance to Pearl Harbor and at 1:16am launches this midget submarine. Aboard is commander Lt. Naoji Iwasa and PO1C Naokichi Sasaki.

This submarine entered Pearl Harbor undetected but was spotted at 8:30am by USS Zane DMS-14 then spotted by USS Breese DM-18 and USS Curtiss AV-4 that opens fire. At 08:36 this submarine fired one torpedo at USS Curtiss AV-4 but missed and instead impacted a dock at Pearl City. The sub is hit by 5" gunfire from Curtiss that damages the sub and decapitates Iwasa. The sub is also hit by .50 caliber machine gun fire.

At 8:37am, USS Monaghan DD-354 spots the periscope and part of the conning tower and prepares to ram while USS Medusa AR-1 and USS Tangier AV-8 both open fire on the submarine. At 8:39am, this sub surfaces and USS Monaghan DD-354 rams it as it fires its second torpedo, which passed harmlessly beneath the destroyer and exploded on the shore of Ford Island. The damaged submarine sinks to the 30' bottom but is blown to the surface when Monaghan dropped two depth atop before it sinks northwest of Ford Island.

Several days after the attack, this submarine was discovered by the U.S. Navy (USN) several days later and dubbed "Midget B", the second submarine. Raised during 1942, this submarine was buried in landfill at the US Navy Submarine Base at Pearl Harbor. Subsequently disinterred then reburied.

Lt Iwasa's sleeve with his rank insignia was recovered from the submarine. Postwar, this was returned to Japan and is displayed at Yūshūkan (Yasukuni Museum) at Yasukuni Jinja (Yasukuni Shrine).

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.

Combined Fleet - Midget Submarines at Pearl Harbor, Hawaii 1941
Combined Fleet - IJN Submarine I-22: Tabular Record of Movement
US Navy Heritage Type A, B & C Midget Submarines-- Japanese Type A Midget Submarines used in the attack on Pearl Harbor (Photo #: NH 54302)
National Geographic Pearl Harbor Timeline - Remembering Pearl Harbor 0839 - Submarine in the West Loch page 5 - Submarine in the West Loch page 6 - Submarine in the West Loch page 7

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Last Updated
October 23, 2019


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