Following the lead of the German Navy in WWI, several countries, including Britain, France, the United States, Italy and the Soviet Union all pursued development of aircraft capable of submarine transport, as well as the submarines capable of carrying them. But no country more so than Japan carried the development of these aircraft and naval vessels to the logical conclusion. During the 1920s, Japan purchased aircraft technology from Germany and submarines from France and Great Britain, and using them as a starting point, developed the most successful submarine launched aircraft and aircraft carrying submarines of any navy before and during WWII.