I-12 was an Imperial Japanese Navy Type A2 long-range fleet submarine that served during World War II. Designed as a submarine aircraft carrier, she was commissioned in May 1944. Her crew committed a war crime when they attacked the survivors of a ship she sank in October 1944. She was sunk in November 1944 during her first war patrol.
Design and description
Type A2 submarines were versions of the preceding Type A1 with less powerful engines, adopted to reduce their construction time. I-12 was the only submarine completed to the original Type A2 design; subsequent Type A2s were constructed to a modified design as the Type AM. Like the preceding Type A1 submarines, I-12 was fitted as a squadron flagship. She displaced on the surface and submerged. She was long and had a beam of and a draft of . She had a diving depth of .
For surface running, I-12 powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. She could reach on the surface and submerged. On the surface, she had a range of at ; submerged, she had a range of at .
I-12 was armed with six internal bow torpedo tubes and carried a total of 18 Type 95 torpedoes. She also was armed with a single /40 deck gun and two twin Type 96 anti-aircraft gun mounts.
As in Type A1 submarines, I-12′s aircraft hangar was integrated into her conning tower and faced forward, and the aircraft catapult was forward of the hangar, while the deck gun was aft of the conning tower. This allowed aircraft launching from I-12 to use the forward motion of the submarine to supplement the speed imparted by the catapult.
Construction and commissioning
Built by Kawasaki at Kobe, Japan, I-12 was laid down as Submarine No. 620 on 5 November 1942. On 5 July 1943 she was renamed I-12 and attached provisionally to the Yokosuka Naval District. She was launched on 3 August 1943 and was completed and commissioned on 25 May 1944.
Service history
May–September 1944
On the day of her commissioning, I-12 was formally attached to the Yokosuka Naval District and assigned to Submarine Squadron 11 in the 6th Fleet for work-ups, with Commander Kaneo Kudo in command, who remained her commanding officer for the submarine's entire career. She departed Kobe, Japan, on 20 September 1944 and conducted work-ups before arriving at Kure, Japan, on 30 September 1944.
First war patrol
The staff of the Combined Fleet ordered the 6th Fleet to send a long-range submarine to disrupt Allied sea lines of communication between the United States West Coast and Hawaii, and the 6th Fleet selected I-12 for the operation. Attached directly to 6th Fleet headquarters, she departed Kobe on 4 October 1944 for her first war patrol, ordered to attack shipping along the U.S. West Coast, in the Hawaiian Islands area, in the Tahiti area, and in the Pacific Ocean east of the Marshall Islands. She proceeded through the Seto Inland Sea and Sea of Japan to Hakodate, where she paused in Hakodate Bay on 7 October 1944 for an overnight stop. She then got back underway and passed through the Tsugaru Strait into the Pacific Ocean.