World War II saw an unprecedented level of inter-Allied cooperation that led to the formation of new staff organizations like the US Joint Chiefs of Staff (JCS) and the US-British Combined Chiefs of Staff (CCS).

In World War II, the three great Allied powers—Great Britain, the United States, and the Soviet Union—formed a Grand Alliance that was the key to victory. But the alliance partners did not share common political aims, and did not always agree on how the war should be fought.

In a series of high-stakes strategic conferences in late 1943, the Allies made several key decisions that shaped wartime strategy, while reflecting the changing balance of power between the Allied nations and foreshadowing the postwar emergence of the bipolar world.

This legislation was the culmination of efforts by American citizens, activists, and politicians across the political spectrum to insulate the United States from foreign conflicts and prevent the country from being drawn into another global war. 

Historian Richard Frank explores the influence of China and the Soviet Union in the Japanese decision to attack American territories in December 1941.