A letter Einstein barely wrote helped launch the atomic bomb

In August 1939, physicist Leo Szilard drafted a warning that Nazi Germany might be building an atomic bomb, and persuaded Albert Einstein to sign it. The letter reached President Roosevelt that October, hand-delivered by an economist rather than mailed, and helped set in motion the research that became the Manhattan Project.

— Leo Szilard and Albert Einstein, Einstein–Szilard letter — 2 August 1939