Answer:
World War II proved to be the deadliest international conflict in history, taking the lives of 60 to 80 million people, including 6 million Jews who died at the hands of the Nazis during the Holocaust.
The major causes of World War II were numerous. They include the impact of the Treaty of Versailles following WWI, the worldwide economic depression, failure of appeasement, the rise of militarism in Germany and Japan, and the failure of the League of Nations.
September 1, 1939 – September 2, 1945