The document summarizes key events leading up to and during World War II. It discusses how European powers were rearming in the 1930s in violation of treaties. World War II officially began in 1939 when Germany invaded Poland. The US initially tried to remain neutral but provided material support to Britain through Lend-Lease. The Japanese attack on Pearl Harbor in 1941 drew the US fully into the war. The US mobilized its economy and citizens for war, though interned Japanese Americans. By 1945, Allied strategies including invasions of North Africa and Europe and atomic bombs on Japan ended the war.