The atomic bombs were kept in secret for years. The first one dropped was Little Boy on Aug 6, 1945. It was dropped on Hiroshima, it leveled 60% of the city and killed 70,000 residents. The second bomb dropped was Fat Man on Aug 6, 1945. It was dropped on Nagasaki and killed over 20,000 residents. Truman, the president at the time, had ok'ed bombing anytime after Aug 3, 1945. Many Japs had died weeks later from the radiation.