Submarines of the Imperial Japanese Navy
The submarines that Electric Boat sold to Japan were based on the Holland designs, known as Holland Type VIIs similar to the American s. The five imported Hollands were originally built at Fore River Ship and Engine Company in Quincy, Massachusetts under Busch's direction for the Electric Boat Company back in August–October 1904. They were shipped by freighter from Seattle, Washington in Knock-down kit form to Japan, and then reassembled by Arthur Leopold Busch at the Yokosuka Naval Arsenal, which was then Japan's largest naval shipyard, to become Hulls No. 1 through 5 and were designated Type 1 submarines by the Japanese Navy.
Submarine aircraft carriers of Japan
Submarine aircraft carriers were developed by the Imperial Japanese Navy to a greater extent than any other navy, before and during World War II. In total, 42 were built, as listed below (other sources say 47). Although other navies had experimented with submarine aircraft carriers, by World War II the IJN was the only navy (aside from one fielded by the French Navy) using them. They had little effect on the war, although two were used to carry out attacks on the continental United States.