Leo Szilard was largely responsible for the creation of the Manhattan Project. He drafted a letter to President Franklin Roosevelt, but in order to get the president to read it, he had to get Einstein to sign it as well. The project to study the possible uses of nuclear chain reactions was began, and he and Fermi attained the first self-sustaining chain reaction in 1942 using uranium and pure graphite rods. The Nazis had attempted to use graphite rods, but theirs had boron impurities, which prevented a chain reaction. Over time, Leo disagreed and fought more with the military's control over the research.
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