The Atomic bombings of the cities of Hiroshima and Nagasaki in Japan were conducted by the United States during the final stages of World War II in August 1945. The two bombings were the first and remain the only use of nucler weapons in warfare.The bomb played a key role in ending World War Two. The atomic bomb (A bomb), created via the Manhattan Project, was first exploded at the top secret base of Alamogordo on July 16th, 1945. This bomb made lots and lots of people really sick and most of them died.