World War II officially started in Europe onÂ September 1, 1939 when Nazi Germany invaded Poland. Great Britain and France responded by formally declaring war against Germany 2 days later. The United States initially distanced itself from the war, until the Japanese aerial bombing ofÂ Pearl Harbor, which made the war global in 1941.
Prior to the outbreak of the Second World War, European nations witnessed the steady rise to power of the Nazi dictator, Adolf Hitler. His imperialistic ideology resulted in the formation of the Axis Powers, with Japan and Italy having similar inclinations of territorial expansion as Hitler. They were eventually defeated in 1945 by the Allied Forces, comprised of Great Britain, the Soviet Union and the United States.