The United States Air Force became a separate military service on 18 September 1947 with the implementation of the National Security Act of 1947. The Act created the National Military Establishment, later renamed the United States Department of Defense, which was composed of four of the five branches, the Army, Marine Corps, Navy, and a newly created Air Force. Prior to 1947, the responsibility for military aviation was divided between the Army for land-based operations and the Navy and Marine Corps for sea-based operations from aircraft carrier and amphibious aircraft. The Army created the first antecedent of the Air Force on 1 August 1907, which through a succession of changes of organization, titles, and missions advanced toward eventual separation 40 years later. The predecessor organizations leading up to today's U.S. Air Force are:
Aeronautical Division, Signal Corps (1 August 1907 – 18 July 1914) Aviation Section, Signal Corps (18 July 1914 – 20 May 1918) Division of Military Aeronautics (20 May 1918 – 24 May 1918) Air Service, U.S. Army (24 May 1918 – 2 July 1926) U.S. Army Air Corps (2 July 1926 – 20 June 1941) U.S. Army Air Forces (20 June 1941 – 17 September 1947)
World War I and between wars
World War I
In 1917, upon the American entry into World War I, the first major U.S. aviation combat force was created when an Air Service was formed as part of the American Expeditionary Force (AEF). Major General Mason Patrick commanded the Air Service of the AEF; his deputy was Brigadier General Billy Mitchell. These aviation units, some of which were trained in France, provided tactical support for the U.S. Army, especially during the Battle of Saint-Mihiel and the Meuse-Argonne offensives. Among the aces of the AEF Air Service were Captain Eddie Rickenbacker and 2nd Lieutenant Frank Luke. Concurrent with the creation of this combat force, the U.S. Army's aviation establishment in the United States was removed from control of the Signal Corps and placed directly under the United States Secretary of War. An assistant secretary was created to direct the Army Air Service, which had dual responsibilities for development and procurement of aircraft, and raising and training of air units. With the end of the First World War, the AEF's Air Service was dissolved and the Army Air Service in the United States largely demobilized.
In 1920, the Air Service became a branch of the Army and in 1926 was renamed the Army Air Corps. During this period, the Air Corps began experimenting with new techniques, including air-to-air refueling and the development of the B-9 and the Martin B-10, the first all-metal monoplane bombers, and new fighters.