Editing I-400-class submarine (section)

==Origins==
The ''I-400'' class was the brainchild of Admiral [[Isoroku Yamamoto]], Commander-in-Chief of the [[Japanese Combined Fleet]]. Shortly after the [[attack on Pearl Harbor]], he conceived the idea of taking the war to the [[United States]] mainland by making aerial attacks against cities along the U.S. western and eastern seaboards using submarine-launched naval aircraft. He commissioned Captain Kameto Kuroshima to make a feasibility study.<ref name="Sakaida15">Sakaida, p. 15.</ref>

Yamamoto submitted the resulting proposal to Fleet Headquarters on 13 January 1942. It called for 18 large submarines capable of making three round-trips to the west coast of the United States without refueling or one round-trip to any point on the globe. They also had to be able to store and launch at least two attack aircraft armed with one torpedo or {{convert|800|kg|abbr=on}} bomb. By 17 March, general design plans for the submarines were finalized. Construction of ''I-400'' commenced at Kure Dock Yards on 18 January 1943, and four more boats followed: ''I-401'' (April 1943) and ''I-402'' (Oct 1943) at Sasebo; ''I-403'' (Sept 1943) at Kobe and ''I-404'' (February 1944) at Kure. Only three were completed.<ref name="Sakaida16">Sakaida, p. 16.</ref>

Following [[Operation Vengeance|Yamamoto's death]] in April 1943, the number of aircraft-carrying submarines to be built was reduced from eighteen to nine, then five and finally three. Only ''I-400'' and ''I-401'' actually entered service; ''I-402'' was completed on 24 July 1945, five weeks before the end of the war, but never made it to sea.<ref name=Sakaida16/>