World War 2
World War II or the Second World War involved the world's leading nations divided into two camps: the Allies and the Axis. More than 70 million people, the majority of them civilians, were killed in the war, making it the deadliest conflict in human history. The man responsible for the War was Adolf Hitler, the Chancellor of the German Republic, who ordered the worst genocide in history.
The war started in September 1939 with the German invasion of Poland and the Allies comprising the United Kingdom, France and the British Dominions going to war against Germany. The Allies eventually won the war when the United States also joined them.