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.
This World War II timeline highlights important dates from April 1940 to December 1940. On May 10, 1940, Hitler had his troops begin the invasion of France in lands the Allies thought impassible by an army. Follow the events of World War II and the German invasion.