See a breakdown of numbers in the US military, by branch and year, in World War II. 

On September 16, 1940, the United States instituted the Selective Training and Service Act of 1940, which required all men between the ages of 21 and 45 to register for the draft.

America's isolation from war ended on December 7, 1941, when Japan staged a surprise attack on American military installations in the Pacific. 

Ask anyone who remembers life on the Home Front during World War II about their strongest memories and chances are they will tell you about rationing. You see, the war caused shortages of all sorts of things: rubber, metal, clothing, etc. But it was the shortages of various types of food that affected just about everyone on a daily basis.

American women played important roles during World War II, both at home and in uniform.