"1939
- August 23 - Germany and the Soviet Union sign the
- Nazi-Soviet Non-Aggression Pact
- September 1 - Germany invades Poland, starting World War 2
- September 3 - Britain and France declare war on Germany
- September - Battle of the Atlantic begins
- May - Auschwitz established
- May 10 - Germany invades France, Belgium, and the Netherlands
- May 26 - Evacuation begins of Allied troops from Dunkirk, France
- June 10 - Italy declares war on France and Great Britain
- June 22 - France surrenders to Germany
- July 10 - Battle of Britain begins
- September 16 - The United States begins its first peacetime draft
- March 11 - U.S. President Franklin D. Roosevelt signs the Lend-Lease bill
- May 24 - The British ship Hood is sunk by Germany's Bismarck
- May 27 - The Bismarck is sunk
- June 22 - Germany invades the Soviet Union (Operation Barbarossa)
- August 9 - Atlantic Conference begins
- September 8 - Siege of Leningrad begins
- December 7 - The Japanese launch a sneak attack on Pearl Harbor, Hawaii
- December 11 - Germany and Italy declare war on the United States; then the United States declares war on Germany and Italy
- January 20 - The Wannsee Conference
- February 19 - Roosevelt issues Executive Order 9066, which allows the internment of Japanese Americans
- April 18 - The Doolittle Raid on Japan
- June 3 - The Battle of Midway begins
- July 1 - First Battle of El Alamein begins
- July 6 - Anne Frank and her family go into hiding
- August 2 - Guadalcanal Campaign begins
- August 21 - Battle of Stalingrad begins
- October 23 - Second Battle of El Alamein begins
- November 8 - The Allies invade North Africa (Operation Torch)
- January 14 - Casablanca Conference begins
- February 2 - The Germans surrender at Stalingrad, Soviet Union
- April 19 - The Warsaw Ghetto Uprising begins
- July 5 - Battle of Kursk begins
- July 25 - Mussolini resigns
- September 3 - Italy surrenders
- November 28 - Tehran Conference begins
- January 27 - After 900 days, the Siege of Leningrad is finally over
- June 6 - D-Day
- June 19 - Battle of the Philippine Sea
- July 20 - Assassination attempt against Hitler fails
- August 4 - Anne Frank and her family are discovered and arrested
- August 25 - The Allies liberate Paris
- October 23 - Battle of Leyte Gulf begins
- December 16 - Battle of the Bulge begins
- February 4 - Yalta Conference begins
- February 13 - Allies begin bombing Dresden
- February 19 - Battle of Iwo Jima begins
- April 1 - Battle of Okinawa
- April 12 - Franklin D. Roosevelt dies
- April 16 - Battle of Berlin begins
- April 28 - Mussolini is hanged by Italian partisans
- April 30 - Adolf Hitler commits suicide
- May 7 - Germany signs an unconditional surrender
- July 17 - Potsdam Conference begins
- August 6 - The United States drops the first atomic bomb on Hiroshima, Japan
- August 9 - The United States drops a second atomic bomb on Nagasaki, Japan"