Despite peacetime rivalries in the drafting of service doctrine, in World War II the immense pressures of wartime drove army and air commanders to cooperate in the effective prosecution of battlefield operations. In northwest Europe during the war, the combination of the U.S. Third Army commanded by Lt. Gen. George S. Patton and the XIX Tactical Air Command led by Brig. Gen. Otto P. Weyland proved to be the most effective allied air-ground team of World War II.