The bomb was dropped on the Japanese city of Hiroshima on August 6 , 1945 by the American army who were trying to end World War II . Enola Gay was the name of the plane that dropped Little Boy . `` Little Boy '' was the codename of the atomic bomb dropped on Hiroshima on August 6 , 1945 by the Boeing B-29 Superfortress Enola Gay , piloted by Colonel Paul Tibbets of the 393d Bombardment Squadron , Heavy , of the United States Army Air Forces .