The United States opened a new era in history when its air forces dropped atomic bombs on Hiroshima and Nagasaki in August 1945. The development of the atomic program, which President Franklin D. Roosevelt (FDR) authorized early in the war, has been treated at length. Initially, the fear was that Germany, where nuclear fission had been discovered in 1938, would be the first nation to construct bombs and use them. Harry S. Truman claimed that he first learned about the atomic program from FDR himself during the summer of 1944, not after he became president as he wrote in his memoirs. The advisers Truman inherited had markedly differing opinions about atomic matters, and some changed their views over time. There was Henry L. Stimson, in whose hands rested overall direction of the atomic program. There has been much debate over the importance the nuclear bomb had on Japan's decision to surrender.