Submarines of the Imperial Japanese Navy
The Imperial Japanese Navy's doctrine of fleet warfare ("guerre d'escadre") resulted in its submarines seldom posing a threat to allied merchant convoys and shipping lanes to the degree that the Kriegsmarine's U-boats did as they pursued commerce raiding against Allied and neutral merchant ships. During the war, IJN submarines did sink about 1 million tons (GRT) of merchant shipping (184 ships) in the Pacific; by contrast U.S. Navy submarines sank 5.2 million tons (1,314 ships) in the same period, while U-boats of Nazi Germany's "Kriegsmarine", the IJN's Axis partner, sank 14.3 million tons (2,840 ships) in the Atlantic and other oceans. During the last two years of the War in the Pacific, many IJN submarines were also occupied serving to transport supplies to isolated island garrisons, ones that had been deliberately bypassed by the Americans and the Australians and which could not be reached by surface transports because of blockade by Allied warplanes and naval vessels.
Yokosuka Naval Arsenal
The Yokosuka Naval District was established at Yokosuka, Kanagawa in 1884, as the first of the naval districts responsible for the defense of the Japanese home islands, and the Yokosuka Shipyards was renamed the Yokosuka Naval Arsenal in 1903. Japan had purchased five submarines from the American Electric Boat Company during the Russo-Japanese War of 1904–1905. These Holland Type VII submarines were built by Arthur Leopold Busch as he traveled to Japan during this time. Mr. Busch was a naval architect and shipbuilder who represented the newly organized company (Electric Boat Company) now located at the Quincy Massachusett's shipyard known as the Fore River Ship and Engine Company. These first five submarines became Japan's (IJN) initial entry into the theater of underwater warfare that began nearly the same time as the outbreak of the war. Another representative of Electric Boat, Frank Cable, an electrician working for Isaac L. Rice's company trained two Japanese crews in the operation of such craft.