An Air Department was established at the Admiralty in 1910 with the initial object of building an airship, but in 1911 it extended its activities to heavier-than-air machines. In 1912 it became responsible jointly with the Directorate of Military Aeronautics of the War Office for the Royal Flying Corps, which had separate naval and military wings.
On 1 July 1914 the naval wing became a separate service as the Royal Naval Air Service, under the sole control of the Air Department. When war broke out a month later the RNAS became responsible for co-operation with the Navy, for bombing naval targets at sea and in port and, until February 1916, for the air defence of the United Kingdom; it also played a part in air operations in France and Flanders and in other theatres of war.
The RNAS was responsible for the design and supply of its own aircraft and equipment and, in time, competition with the Royal Flying Corps produced problems. The joint War Air Committee set up in February 1916 and its successor, the first Air Board, were intended to co-ordinate the activities of the two services in the field of aircraft supply, but they had no executive powers and were of limited effectiveness. However, the second Air Board set up in January 1917 was appointed to have responsibility for aircraft design, inspection and allocation for both services, while at the same time, the Ministry of Munitions became responsible for supply and inspection of aeroplanes, seaplanes, engines and accessories.
On 3 January 1918 control of the RNAS, with the exception of its airships and balloons, which had become the responsibility of the director of naval construction in 1916 and which the Admiralty retained until 1919, passed to the Air Ministry and on 1 April 1918 it was merged with the RFC as the Royal Air Force. The Admiralty retained control of the aircraft carriers and of operations at sea, and naval officers and ratings were seconded to the RAF for training and service; but the administration of the Fleet Air Arm and all its activities ashore remained under the control of the Air Ministry, despite continuous Admiralty opposition, until July 1937, when agreement was reached for the return of the Fleet Air Arm to the Admiralty. The transfer was not completed until 1939. At first only carrier-borne aircraft were involved, and not until April 1941 did operational control of the land-based Coastal Command pass to the Admiralty. In November 1969 Coastal Command was absorbed into Strike Command.
At the Admiralty, naval aviation became the responsibility of the Fifth Sea Lord. An Air Division of the Naval Staff, an Air Branch of the Secretary's Department and various other departments responsible for equipment and spares and liaison with the Ministries concerned in aircraft supply, were set up. The Admiralty did not have its own organisation for aircraft supply; this remained an Air Ministry responsibility until 1940, when it passed to the Ministry of Aircraft Production.