World War II was a global war that started in 1937 in Asia and 1939 in Europe, involving all major powers across continents. It resulted in an estimated 50-80 million deaths, making it the deadliest conflict in history. The war was caused by struggles that emerged in the interwar period after WWI, as nationalist sentiment in Germany gave rise to new dictatorships like fascism in Italy and increased militarism in Japan. One of the most significant causes was the rise of the Nazi party in Germany in 1933, as totalitarian regimes in Germany, Italy, and Japan consolidated power in the lead up to WWII.