For starters, because each country had fought a different war. Though the United States had fought valiantly on land and at sea on three continents (Europe, Asia-Pacific, and Africa), it had entered the war relatively late, in December 1941, and ‘only’ lost around 300,000 men. Not only was none of the conflict (outside Hawaii) fought on American soil, but its economy emerged as the world’s most powerful as a direct result, accounting for over 50% of global gross domestic product (GDP) by 1945.