During the Summer of 1943, with U.S. planes raiding Germany during the day, the Royal Air Force continued their carpet bombing at night. On July 24, 791 RAF planes struck at Hamburg -- Germany's second largest city and Europe's second largest port. For six straight days, Hamburg was attacked by Allied bombs. The raids resulted in the first ever firestorm. Almost three quarters of the city was destroyed, and over 40,000 people died in the blazes.