The Manhattan Project

On August 2, 1939, Albert Einstein signed a letter to President Franklin Delano Roosevelt. The letter, written almost entirely by Einstein’s former graduate student Leó Szilárd, warned Roosevelt about the imminent development of a German atomic bomb that relied upon a chain reaction of a large mass of uranium and urged him to sponsor his American research, with the goal of beating the Germans. The letter pointed out that the Germans had already restricted the sale of uranium, presumably to divert it toward military purposes. This letter—known as the Einstein-Szilárd letter—resulted in the creation of the Advisory Committee on Uranium, headed by the physicist Lyman J. Briggs. This committee was eventually replaced by a high-level group, code-named the “S-1 Committee,” which was chaired by Harvard’s James B. Conant, who reported directly to the White House. In 1942, the S-1 Committee came under the authority of General Leslie Groves, at which time it was known as the Manhattan District, better known today as the Manhattan Project.