Hiroshima Peace Day falls on August 6 and Nagasaki Peace Day on August 9. The two days to remind the world of the destruction that a war can wreck. According to estimates the bombs killed a large number of people – with the majority of the causalities having died from flash or flame burns. What happened? In 1945, the United States of America dropped two atomic bombs on the cities of Hiroshima and Nagasaki in Japan. On August 6, the nuclear weapon “Little Boy” was dropped on Hiroshima because it was a city of considerable military importance and contained Japan's Second Army Headquarters. It also was the communications centre and storage depot. On August 9, at 11:02 a. m. , at an altitude of 1,650 feet, Fat Man (right) exploded over Nagasaki. The yield of the explosion was later estimated at 21 kilotons, 40 percent greater than that of the Hiroshima bomb. Within the first two to four months of the bombings, the acute effects killed 90,000 – 166,000 people in Hiroshima and 60,000 – 80,000 in Nagasaki, with roughly half of the deaths in each city occurring on the first day. Six days after the detonation over Nagasaki, on August 15, Japan announced its surrender to the Allied Powers, signing the Instrument of Surrender on September 2, officially ending the Pacific War and therefore World War II. Germany had signed its Instrument of Surrender on May 7, ending the war in Europe. The bombings led, in part, to post-war Japan adopting Three Non-Nuclear Principles, forbidding the nation from nuclear armament.