Once the atomic bomb became a reality, there was intense debate between the scientists who had been involved in the weapons program and the politicians who oversaw it about if, and how, it should be used. The final decision fell to Harry S Truman, who had ascended to the presidency after the death of Roosevelt in April of 1945. Truman, who had served as Roosevelt’s vice president, was probably unaware of the Manhattan Project until he took the presidency. The decision he faced now would change the course of history.