In 1917, upon the United States’ 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. Maj. Gen. Mason Patrick commanded the Air Service of the AEF; his deputy was Brig. Gen. 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.
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.
During World War I, aviation technology developed rapidly; however, the Army’s reluctance to use the new technology began to make airmen think that as long as the Army controlled aviation, development would be stunted and a potentially valuable force neglected.
Air Corps senior officer Billy Mitchell began to campaign for Air Corps independence. But his campaign offended many and resulted in a court martial in 1925 that effectively ended his career. His followers, including future aviation leaders “Hap” Arnold and Carl Spaatz, saw the lack of public, congressional, and military support that Mitchell received and decided that America was not ready for an independent air force. Under the leadership of its chief of staff Mason Patrick and, later, Arnold, the Air Corps waited until the time to fight for independence arose again.