The Second World War was a global war lasting from 1939 to 1945, involving over 30 countries and 100 million people divided into two alliances - the Allies and Axis powers. It resulted in 50-85 million fatalities, more than any other war in history, and included mass civilian deaths such as the Holocaust and bombings of cities. Major turning points included Germany's defeat at Stalingrad, the Allied invasion of Normandy, and the United States dropping atomic bombs on Hiroshima and Nagasaki, leading Japan to surrender in August 1945.