Second World War
The Second World War was a global war that involved fighting in most of the world. Most countries fought from 1939 to 1945, but some started fighting in 1937. Most of the world's countries, including all of the great powers, fought as part of two military alliances: the Allies and the Axis Powers. It involved more countries, cost more money, involved more people, and killed more people than any other war in history. Between 50 to 85 million people died, most of whom were civilians. The war included massacres, a genocide called the Holocaust, strategic bombing, starvation, disease, and the only use of nuclear weapons against civilians in history.