On 11 April 1945, at the conclusion of a ten-month study that took them to every major theater to interview 80 "key military and naval personnel," the Joint Chiefs of Staff Special Committee for the Reorganization of National Defense recommended that the armed forces of United States be organized into a single cabinet department, and that "three coordinate combat branches, Army, Navy, and Air" comprise the operational services. The committee reported that the statutory creation of a United States Air Force would merely recognize a situation that had evolved during World War II with the Army Air Forces, acknowledging that naval/marine aviation and some aspects of army aviation would remain in place. The committee also reported that its recommendation was approved by "Generals of the Army Douglas MacArthur and Dwight D. Eisenhower, Fleet Admirals Chester W. Nimitz and William F. Halsey and numerous other leading military and naval personnel."
The United States Army Air Forces incurred 12% of the Army's 936,000 battle casualties in World War II. 88,119 airmen died in service. 52,173 were battle casualty deaths: 45,520 , 1,140 died of wounds, 3,603 were and declared dead, and 1,910 were non-hostile battle deaths. Of the United States military and naval services, only the Army Ground Forces suffered more battle deaths. 35,946 non-battle deaths included 25,844 in aircraft accidents, more than half of which occurred within the Continental United States. 63,209 members of the USAAF were other battle casualties. 18,364 were and required medical evacuation, and 41,057 became . Its casualties were 5.1% of its strength, compared to 10% for the rest of the Army.
In the spring of 1941, the success in Europe of air operations conducted under centralized control made clear that the splintering of authority in the American air forces, characterized as "-headed" by one congressman, had caused a disturbing lack of clear channels of command. Less than five months after the rejection of Arnold's reorganization proposal, a joint U.S.-British strategic planning agreement () refuted the General Staff's argument that the Air Corps had no wartime mission except to support ground forces. A struggle with the General Staff over control of air defense of the United States had been won by airmen and vested in four command units called "numbered air forces", but the bureaucratic conflict threatened to renew the dormant struggle for an independent United States Air Force. Marshall had come to the view that the air forces needed a "simpler system" and a unified command. Working with Arnold and , recently appointed to the long-vacant position of Assistant Secretary of War for Air, he reached a consensus that quasi-autonomy for the air forces was preferable to immediate separation.