S-1 Section

The Uranium Committee was a committee of the National Defense Research Committee (NDRC) that succeeded the Advisory Committee on Uranium and later evolved into the S-1 Section of the Office of Scientific Research and Development (OSRD), when that organization absorbed the NDRC in June 1941, and the S-1 Executive Committee in June 1942. It laid the groundwork for the Manhattan Project by initiating and coordinating the early research efforts in the United States, and liaising with the Tube Alloys Project in Britain.

The discovery of uranium fission in December 1938, reported in the January 6, 1939 issue of Die Naturwissenschaften by Otto Hahn, and Fritz Strassmann, and its correct identification as nuclear fission by Lise Meitner in the February 11, 1939 issue of Nature, generated intense interest among physicists. Even before publication, the news was brought to the United States by Danish physicist Niels Bohr, who opened the Fifth Washington Conference on Theoretical Physics with Enrico Fermi on January 26, 1939. The results were quickly corroborated by experimental physicists, most notably Fermi and John R. Dunning at Columbia University.

The possibility that Nazi Germany might develop nuclear weapons was particularly alarming to scientists from Germany and other fascist countries. Two of them, Leo Szilard and Eugene Wigner drafted the Einstein–Szilárd letter to U.S. President Franklin Delano Roosevelt. It advised Roosevelt of the existence of the German nuclear weapon project, warned that it was likely the Germans were working on an atomic bomb using uranium, and urged that the United States secure sources of uranium and conduct research into nuclear weapon technology. At this time the United States was still neutral in the war. This letter was signed by Albert Einstein on August 2, 1939, but its delivery was delayed because of the outbreak of World War II in Europe with the German invasion of Poland in September 1939. The letter was eventually hand-delivered to Roosevelt by the economist Alexander Sachs on October 11, 1939. On that date he met with the President, the President's secretary, Brigadier General Edwin "Pa" Watson, and two ordnance experts, Army Lieutenant Colonel Keith F. Adamson and Navy Commander Gilbert C. Hoover. Roosevelt summed up the conversation as: "Alex, what you are after is to see that the Nazis don't blow us up." He told Watson: "This requires action."

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