On 7 December 1941, while German armies were freezing before Moscow, Japan suddenly pushed the United States into the struggle by attacking the American naval base at Pearl Harbor, Hawaii. Four days later Hitler declared war on the United States. President Roosevelt called on Congress for immediate and massive expansion of the armed forces. Twenty years of neglect and indifference, however, could not be overcome in a few days.
Helpless as American garrisons in the Pacific fell to the Japanese in the spring of 1942, military leaders in Washington worked feverishly to create a headquarters that could direct a distant war effort and to turn the fledgling ground and air units into viable, balanced fighting forces. In early 1942 the Joint Chiefs of Staff emerged as a committee of the nation's military leaders to advise the President and to coordinate strategy with the British. In March the War Department General Staff was reorganized and the Army divided into three major commands: the Air Forces, Ground Forces, and Service Forces. Thirty-seven Army divisions were in some state of training, but only one was fully trained, equipped, and deployable by January