World War II (WWII or WW2) was a global war involving fighting in most of the world and most countries. The war started in 1939 with Nazi Germany invading Poland, so most countries fought from 1939 to 1945. However, Japan invaded China in 1937, so 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 was the largest and deadliest conflict in all of history. It involved more countries, cost more money, involved more people, and killed more people than any other war in history.1 Between 50 to 85 million people died,23 most of whom were civilians. The war included massacres, the genocide of the Holocaust,
strategic bombing, starvation, disease, and the only use of nuclear weapons against civilians in history.
The two sides were the Allies (at first China, France and the United Kingdom, joined by the Soviet Union,
United States and others) and the Axis (Germany, Italy and Japan). The war in Asia began when Japan invaded China on July 7, 1937.4 The war began in Europe when Germany invaded Poland on
September 1, 1939. France and the United Kingdom reacted by declaring war on Germany. By 1941
