Germany invades Denmark and Norway with the first major airborne attacks on Allied forces.

Germany invades Belgium, Holland and Luxembourg. Because of the failure of his appeasement policies, British Prime Minister Neville Chamberlain resigns. Forming a coalition government, Winston Churchill replaces him. Standing alone, Churchill soon began conferring with U.S. President Franklin Roosevelt for aid to the British cause.

Leaving behind weapons and supplies at Dunkirk, the British evacuate over 338,000 soldiers from France.

Italy declares war against the Allies. Great Britain, France, Australia, Canada, New Zealand, India and South Africa declare war on Italy. General Hering, the military governor of Paris, declares the French capital an open city to prevent its destruction.

France accepts German armistice terms, establishing the Vichy Government under Marshal Petain.

A British airborne attack sinks French vessels at Oran and Mers-el-Kebir to prevent them from passing into German possession.

The Battle of Britain begins. The air war designed to destroy the RAF and ease the German invasion opens with the Luftwaffe outnumbering its opponent in operational aircraft: 2,669-to-704.

The London Blitz starts as Germany, attempting to weaken the country's resolve, bombs the British capital.

The U.S. Congress passes the Selective Service Act. It calls for the first peacetime draft in American history. To serve, men had to be five feet tall, weigh 105 pounds, have correctable vision and at least half their teeth.

Close to 16 million American men between the ages of 21 and 36 are required to register at one of 6,500 draft boards across the country. Nearly 50 million men would register during the war.

The Italians invade Greece.