Air Service to become the Royal Air Force, a condition which would remain until 1937.) Moffett supervised the development of naval air tactics throughout the '20s. The first aircraft carrier entered the U.S. fleet with the conversion of the collier USS Jupiter and its recommissioning as in 1922. Many British naval vessels carried float planes, seaplanes or amphibians for reconnaissance and spotting: two to four on battleships or battlecruisers and one on cruisers. The aircraft, a Fairey Seafox or later a Supermarine Walrus, were catapult-launched, and landed on the sea alongside for recovery by crane. Several submarine aircraft carriers were built by Japan, each carrying one floatplane, which did not prove effective in war. The French Navy built one large submarine, , which also carried one floatplane, and was also not effective in war. World War II World War II saw the emergence of naval aviation as the decisive element in the war at sea. The principal users were Japan, United States (both with Pacific interests to protect) and Britain. Germany, the Soviet Union, France and Italy had a lesser involvement. Soviet Naval Aviation was mostly organised as land-based coastal defense force (apart from some scout floatplanes it consisted almost exclusively of land-based types also used by its air arms). During the course of the war, seaborne aircraft were used in fleet actions at sea (Midway, ), strikes against naval units in port (Taranto, Pearl Harbor), support of ground forces (Okinawa, Allied invasion of Italy) and anti-submarine warfare (the Battle of the Atlantic). Carrier-based aircraft were specialised as dive bombers, torpedo bombers, and fighters. Surface-based aircraft such as the PBY Catalina helped finding submarines and surface fleets. In World War II the aircraft carrier replaced the battleship as the most powerful naval offensive weapons system as battles between fleets were increasingly fought out of gun range by aircraft. The Japanese , the most powerful battleship ever built, was first turned back by light escort carrier aircraft and later sunk lacking its own air cover. During the Doolittle Raid of 1942, 16 Army medium bombers were launched from the carrier Hornet on one-way missions to bomb Japan. All were lost to fuel exhaustion after bombing their targets and the experiment was not repeated. Smaller carriers were built in large numbers to escort slow cargo convoys or supplement fast carriers. Aircraft for observation or light raids were also carried by battleships and