When Chester went outside, the Bristish man mentioned that "everyone is celebrating" due to the success of Little Boy. "Little Boy" was the codename for the type of atomic bomb dropped on the Japanese city of Hiroshima on August 6, 1945 during World War II. It was the first nuclear weapon used in warfare. It weighted 9,700 pounds (4,400 kg), had a length of 10 feet (3.0 m), and a diameter of 28 inches (71 cm). It was filled with Uranium-235, which weighted 141 lbs (64kg). The explosion had a blast yield of 15 kilotons of TNT (63 TJ). There were a total of 26 made. Then, on August 9, 1945, U.S. forces dropped "Fat Man," a plutonium bomb, on Nagasaki. Together, the two bombs dropped in Japan would kill more than 300,000 people, including those who died instantly and those who perished from radiation and other lingering effects of the explosions. Emperor Hirohito announced Japan's unconditional surrender via radio address on August 15, 1945, bringing World War II to a close.