World war 2 ended in 1945
Pearl Harbor. The atomic bombs that we dropped on Japan was revenge for Pearl Harbor. We already had some issues with Japan but the surprise attack on Pearl Harbor was the main reason for the atomic bombs that President Truman dropped on Japan.
A. The Holocaust
German Nazis felt that Jews and any one else who was not part of the master race of Aryans (blonde hair, blue eyes) were inferior so they were sent to death camps called Concentration Camps and were systematically killed.
A. To make them feel blame for what happened