World War II was the defining disaster for millions of people across the globe. In addition to the total war experienced in World War I, the conflict stretched across the entire planet, not just parts of Europe, Africa, and the Middle East. While nationalist rivalries and international tensions certainly led to the war, the primary cause was unquestionably Adolf Hitler's personal obsession with creating a vastly expanded German empire. (Note: Germany, Italy, Japan, and their allies are referred to as "The Axis" in World War II. Britain, the US, the USSR, and their allies are referred to as "The Allies".) By the war's end, approximately 55 - 60 million people had died, including 25 million Soviets and 6 million Jewish victims of the Holocaust.