WW2
More than 50 countries took part in World War II, the greatest and deadliest combat in human
history, which was fought on land, at sea, and in the air in almost every continent. The war
started when Nazi Germany invaded Poland in 1939 and raged across the globe until 1945,
when Japan surrendered to the United States after atomic bombs were dropped on Hiroshima
and Nagasaki. The war, also known as the Second World War, was caused in part by the
economic crisis of the Great Depression and by political tensions left unresolved after the end
of World War I. Approximately 60 to 80 million people, including up to 55 million civilians, had
perished by the end of World War II, and major cities in Europe and Asia was left in ruins. As part
of Hitler's evil "Final Solution," now known as the Holocaust, 6 million Jews were slaughtered in
Nazi concentration camps. The United Nations' founding as a peacekeeping organization and
the geopolitical conflicts that led to the Cold War were two of the war's legacies.