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
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.
In 1939, a group of scientists, many having recently arrived in the United States after fleeing Nazi persecution in Germany, informed government officials that recent experiments conducted in Germany had demonstrated the feasibility of building an atomic weapon.