55,000 aircrew and 12 aircraft handling ships, such as , , and , (later called aircraft carriers), air power had indicated what it was capable of in naval warfare. With wireless and new aircraft such as the DH.6 now available, effective ASW missions could be carried out to the extent that aircraft became one of the core instruments in trade defence. Co-operation was also a breeding ground for tactical doctrine. But the surrender of Germany in November 1918 and mass demobilisation saw maritime aviation enter terminal decline for the next 20 years. By 1918 the RNAS had made far more contributions to long-range maritime air operations than either the RFC or its successor the RAF. In August 1914 the primary role for the maritime services was air defence from enemy attack, maritime reconnaissance, and ASW. ASW was considered the most important. During the course of the coming war, the RFC would be mainly responsible for over-land operations, whilst the RNAS partook in all aspects of aerial warfare; strategic air defence, strategic bombing, ASW and fleet reconnaissance. Prior to the formation of the RAF in April 1918, maritime air operations were the responsibility of the RNAS. When the RAF was formed in April 1918, these operations became their domain. No. 10 Group RAF was given the task. In September 1919 RAF Coastal Area was formed as the Air Ministry's maritime arm. After the formation of the Air Ministry and the RAF in April 1918, Coastal Area was subordinated to the new service but after the war received little encouragement or assistance from the Air Ministry for developing their service. Ignoring past lessons Despite the fact that Britain had been caused severe difficulty by the U-boat campaign in the First World War, the Admiralty completely ignored the threat of the submarine until the late 1930s. The Royal Navy had founded its traditional defensive strength on the battleship, which was used to defend its waters and merchant fleets. This weapon had proved incapable of countering U-boats during the war. The Admiralty also ignored the damage caused by submarines and regarded them as ineffective defensive weapons. Given the disarmament of Germany there seemed little offensive threat. Even after the rise of Adolf Hitler and the birth of the Third Reich, there seemed little inclination or will toward rearming Britain's ASW air forces. To the contrary, the Anglo-German Naval agreement signed in June 1935, allowed