The Einstein–Szilard letter was a historic document sent to President Franklin D. Roosevelt on August 2, 1939. Authored by Leo Szilard and signed by Albert Einstein, the letter served as a formal warning regarding the potential for Germany to develop atomic bombs.
To ensure the letter's impact, Szilard consulted with fellow physicists Edward Teller and Eugene Wigner. The correspondence successfully alerted the American government to the strategic necessity of initiating its own nuclear research program, effectively setting the stage for the Manhattan Project.