late; coupled to incompetent doctrine and organization, it could have had little effect in any case. Late in the war, the Japanese Army and Navy used Magnetic Anomaly Detector (MAD) gear in aircraft to locate shallow submerged submarines. The Japanese Army also developed two small aircraft carriers and Ka-1 autogyro aircraft for use in an antisubmarine warfare role, while the Navy developed and introduced the Kyushu Q1W anti-submarine bomber into service in 1945. The Japanese depth charge attacks by its surface forces initially proved fairly unsuccessful against U.S. fleet submarines. Unless caught in shallow water, a U.S. submarine commander could normally escape destruction, sometimes using temperature gradients (thermoclines). Additionally, IJN doctrine emphasized fleet action, not convoy protection, so the best ships and crews went elsewhere. Moreover, during the first part of the war, the Japanese tended to set their depth charges too shallow, unaware U.S. submarines could dive below 150 feet (45m). Unfortunately, this deficiency was revealed in a June 1943 press conference held by U.S. Congressman Andrew J. May, and soon enemy depth charges were set to explode as deep as 250 feet (76m). Vice Admiral Charles A. Lockwood, COMSUBPAC, later estimated May's revelation cost the navy as many as ten submarines and 800 crewmen. Much later in the war, active and passive sonobuoys were developed for aircraft use, together with MAD devices. Toward the end of the war, the Allies developed better forward-throwing weapons, such as Mousetrap and Squid, in the face of new, much better German submarines, such as the Type XVII and Type XXI. British and Dutch submarines also operated in the Pacific, mainly against coastal shipping. Post-World War II In the immediate postwar period, the innovations of the late war U-boats were quickly adopted by the major navies. Both the United Kingdom and The United States studied the German Type XXI and used the information to modify WW2 fleet boats, the US with the GUPPY program and the UK with the Overseas Patrol Submarines Project. The Soviets launched new submarines patterned on Type XXIs, the Whiskey and Zulu classes. Britain also tested hydrogen peroxide fuels in Meteorite, Excalibur, and Explorer, with less success. To deal with these more capable submarines new ASW weapons were essential. This new generation of diesel electric submarine, like the Type XXI before it, had no deck gun and a streamlined hull tower for greater underwater speed, as well as more