pushed the bomb
Einstein's greatest role in the invention of the atomic bomb was signing a letter to President Franklin Roosevelt urging that the bomb be built. The splitting of the uranium atom in Germany in December 1938 plus continued German aggression led some physicists to fear that Germany might be working on an atomic bomb. Among those concerned were physicists Leo Szilard and Eugene Wigner. But Szilard and Wigner had no influence with those in power. So in July 1939 they explained the problem to someone who did: Albert Einstein. According to Szilard, Einstein said the possibility of a chain reaction "never occurred to me", altho Einstein was quick to understand the concept (Clark, pg. 669+; Spencer Weart & Gertrud Weiss Szilard, eds., "Leo Szilard: His Version of the Facts", pg. 83). After consulting with Einstein, in August 1939 Szilard wrote a letter to President Roosevelt with Einstein's signature on it. The letter was delivered to Roosevelt in October 1939 by Alexander Sachs, a friend of the President. Germany had invaded Poland the previous month; the time was ripe for action. That October the Briggs Committee was appointed to study uranium chain reactions.
But the Briggs Committee moved very slowly, prompting Einstein, Szilard, and Sachs to write to FDR in March 1940, pointing again to German progress in uranium research (Weart & Szilard, pg. 119+). In April 1940 an Einstein letter, ghost-written by Szilard, pressed Briggs Committee chairman Lyman Briggs on the need for "greater speed" (Weart & Szilard, pg. 125+; Clark, pg. 680).
shut up and play your guitar 
