World War II begins when Nazi Germany invades Poland’s capital in a massive encirclement attack. Within weeks of the invasion, German forces defeat the Polish army and receive Warsaw’s official surrender.
September 27, 1940
Germany launches an invasion of Belgium, the Netherlands, Luxembourg, and France. Within a few weeks, all but France have surrendered.
June 22, 1941
Germany begins its bombing raid against Great Britain in the Battle of Britain.
December 7, 1941
Germany, Italy, and Japan sign the Tripartite Pact in Berlin to formalize the alliance of the Axis Powers. The Pact provides for mutual assistance should any of its members suffer attack by any nation not already involved in the war.
In the largest German military effort of World War II, Nazi Germany launches Operation Barbarossa, the invasion of the Soviet Union. Within a few weeks, the Soviet Union has formally joined the Allied nations.
Japan launches a surprise attack on American soil and bombs Hawaii’s naval base at Pearl Harbor on the island of Oahu. More than 2,300 American soldiers and sailors die in the attack, and another 1,100 are wounded.