User: What started WW2?
Assistant: The instability created in Europe by the First World War (1914-18) set the stage for another international conflict—World War II—which broke out two decades later and would prove even more devastating. Rising to power in an economically and politically unstable Germany, Adolf Hitler, leader of the Nazi Party, rearmed the nation and signed strategic treaties with Italy and Japan to further his ambitions of world domination. Hitler’s invasion of Poland in September 1939 drove Great Britain and France to declare war on Germany, marking the beginning of World War II. Over the next six years, the conflict would take more lives and destroy more land and property around the globe than any previous war.