World War II had several major causes and turning points:
1. Political instability and economic devastation following WWI led to the rise of fascist dictators like Hitler, Mussolini, and Tojo who led the Axis powers of Germany, Italy, and Japan.
2. The US initially pursued neutrality but gradually provided more aid to the Allies and entered the war after the Japanese attack on Pearl Harbor in 1941.
3. Major Allied victories like the Battle of Midway and D-Day helped turn the tide of the war, which ended with the US dropping atomic bombs on Hiroshima and Nagasaki in 1945.