September 3, 1939: Britain and France declare war on Germany.
November 30, 1939: The Soviet Union invades Finland, starting the Winter War.
April 9, 1940: Germany invades Denmark and Norway.
May 10, 1940: Germany invades Belgium, the Netherlands, and Luxembourg.
May 26, 1940: France surrenders to Germany.
June 10, 1940: Italy declares war on France and Britain.
June 22, 1940: The Battle of Britain begins.
September 27, 1940: The Tripartite Pact is signed between Germany, Italy, and Japan.
December 7, 1941: Japan bombs Pearl Harbor, bringing the United States into World War II.