The Second World War was indeed the bloodiest period in American history. With approximately fifty nations involved in the conflict and men and women battling almost everywhere, it expanded to encompass the entire planet. The U.S. had an uncompromising stance before the start of the Second World War, indicating that it eschewed getting involved in other countries wars and concentrated on internal problems. The preemptive strike by Japan on the American Pearl Harbor naval base on December seventh, nineteen forty-one, was the last event that triggered the United States' participation in the Second World War.