War Begins. In the early hours of Friday, September 1, 1939, the German armies stormed across the Polish frontierwithout a declaration of war. The Free City of Danzig (the presentday city of Gdansk, Poland, which was then an independent territory) was proclaimed a German city by Nazi agitators in the city. Two days later Great Britain and France declared war on Germany.Important dates in Europe and northern Africa: 1939-1942
Japan's bombing of Pearl Harbor was the major event that caused the United States to enter World War II. On December 7, 1941, Japan bombed the harbor, which damaged 300 planes, eight battleships, and killed over 2,000 people. Learn more about the attack.
World War II was a horrific period in history during which 50 million people perished from death camps, atomic bombs, and years of battle. Often called the Janus event of the 20th century, WWII is truly unforgettable. Learn how the Allies defeated Nazi Germany.