World War 2 lasted from 1939 to 1945 and involved two opposing military alliances: the Allies and the Axis powers. The Axis included Germany, Italy, and Japan, while the Allies included Britain, the Soviet Union, and the United States. Over 60 million people died in the war, including around 40 million civilians. Germany invaded Poland in 1939, drawing Britain and France into the war. By 1945, the Allies had defeated the Axis powers, culminating in the US dropping atomic bombs on Hiroshima and Nagasaki, leading Japan to surrender and ending World War 2.