On 16 September 1940, US President Franklin D Roosevelt signed the Selective Service Act into law. It required all males from the age of 21 to 35 to register for the draft. The Selective Service Act of 1940 was the first peacetime draft in American history. With Japan overrunning large portions of China, Germany possessing most of Europe and poised to invade Britain, and the Soviets, an ally of Germany, controlling most of Eastern Europe, FDR thought it prudent to prepare the US for war. The law also mobilized the National Guard and called up the officer reserves.
“America stands at the crossroads of its destiny. Time and distance have been shortened. A few weeks have seen great nations fall. We cannot remain indifferent to the philosophy of force now rampant in the world. We must and will marshal our great potential strength to fend off war from our shores. We must and will prevent our land from becoming a victim of aggression.” — FDR 16 September 1940