Principal American participants at the Casablanca Conference in French Morocco. Hanning meetings on Allied war strategy between President Roosevelt, Prime Minister Churchill, and the Combined Chiefs of Staff in January 1943 included Lieutenant General Henry Arnold, Commanding General, USAAF. Seated, left to right, General George Marshall, President Roosevelt, and Admiral Ernest King. Standing, left to right, Harry Hopkins, General Arnold, General Brehon Somervell, and Averell Harriman.
These initial steps toward organizing air power as an independent, unified force also led Army Chief of Staff George Marshall to issue Field Manual 100-20 in 1943. This document, the USAAF's "declaration of independence," recognized "land power and air power" to be "coequal and interdependent forces." In the Mediterranean, the Twelfth Air Force neutralized the Luftwaffe when Allied forces invaded Sicily in July and the Italian peninsula in September. Tough fighting slowed Lieutenant General Mark Clark's forces as they pushed northward, forcing him to rely increasingly on USAAF assistance to break through German lines. Since the bombing of the abbey at Monte Cassino failed to break the stalemate on the ground, USAAF units focused their attention on interdiction. Operation STRANGLE hoped to cut the flow of supplies to German defenders in Italy. The Twelfth Air Force learned how difficult that could be. Downing bridges, strafing trains and trucks, and bombing supply dumps contributed to eventual victory in 1945, but the protection of darkness gave the enemy opportunities to supply its forces.