Japanese submarine I-51
Following World War I, the Imperial Japanese Navy General Staff began to re-consider submarine warfare as an element of fleet strategy. Before the war, the Japanese Navy regarded submarines as useful only for short-range coastal point defense. However, based on the success of the Imperial German Navy in deployment of long-range cruiser-submarines for commerce raiding Japanese strategists came to realize possibilities for using the weapon for long range reconnaissance, and in a war of attrition against an enemy fleet approaching Japan. Procurement for a large, long-range Japanese submarine was authorized in fiscal 1918 under the Eight-six fleet program, under the designation S22.
"Project S22" was based on the latest Royal Navy design, the British K class submarine. Japanese ties to Great Britain via the Anglo-Japanese Alliance were still strong. "Project S22" was laid down at Kure Naval Arsenal on 6 April 1921, launched on 29 November 1921 and completed on 20 June 1924.
Japanese submarine I-25
Two submarines were sighted on 11 October 1942 about off the coast of Washington as "I-25" was returning to Japan. "I-25" fired its last torpedo at the lead submarine, which sank in 20 seconds with the loss of all hands. "I-25" reported sinking a U.S. submarine, but the submarine was actually Soviet "L-16" which was sailing with "L-15" en route from Vladivostok to the Panama Canal via Unalaska, Alaska and San Francisco. United States Navy Chief Photographer's Mate Sergi Andreevich Mihailoff of Arcadia, California, was aboard "L-16" as a liaison officer and interpreter, and was killed with the remainder of the submarine crew. The United States Navy Western Sea Frontier denied loss of any submarine and withheld information about the Soviet loss because, at the time, the Soviet Union was officially neutral in the war between Japan and the United States.