The emergence of the heavy bomber in 1935 coincided with the advent of the General Headquarters (GHQ) Air Force. The circumstances leading up to the two events were closely related and actually influenced each other. The idea of an "air force," separate from the support aviation assigned to the Army units, had been urged by Major General Mason Patrick and his successor, Major General James Fechet, Chief of the Air Corps from 1927 to 1931. But the Army General Staff had not been able to see what mission the air arm could have apart from army support. Nor did it agree that aviation should be concentrated under a single air command for use in the field. However, the growing importance of coastal defense provided the Air Corps with a mission that could be performed independently of the ground armies, thus helping pave the way for the GHQ Air Force.
In October 1933, a War Department board headed by Deputy Chief of Staff Major General Hugh A. Drum, reviewed the Air Corps proposal and endorsed the idea of a GHQ Air Force, although it did not accept the emphasis placed on air power by the Air Corps. The Air Corps had recommended a GHQ Air Force comprised of bombardment, attack, and pursuit planes under its control to provide coastal defense. The Drum Board suggested that the force be used for tactical and strategic operations, including attacks on major installations in enemy territory.
The War Department appointed former Secretary of War Newton D. Baker to head a board to study operations of the Air Corps and what its proper relation to civil aviation should be. In July 1934 the board released its findings. It rejected the proposal for an independent air force and a unified defense department. It denied the claims made by Air Corps officers and their adherents and clearly expressed its attitude: "Independent air missions have little effect upon the issue of battle and none upon the final outcome of war." The Baker Board did recommend creation of a GHQ Air Force made up of air combat units capable of operating either independently or in cooperation with ground forces.
On the last day of 1934, the War Department ordered the creation of the GHQ Air Force as of 31 March 1935. The new command went to Brigadier General Frank M. Andrews, a member of the General Staff and one of the ablest officers in the Air Corps. From his headquarters at Langley Field, Virginia, Andrews concentrated tactical units under three wings, at Langley, Barksdale (La.), and March (Calif.) Fields.
See this article from the Sep 2008 issue of Air Force Magazine by John T. Correll: GHQ Air Force.
Read this excerpt from Aviation in the U.S. Army, 1919-1939, by Maurer Maurer: Part 3--GHQ Air Force.