Quote from dannen.com -
In the summer of 1939, six months after the discovery of uranium fission, American newspapers and magazines openly discussed the prospect of atomic energy. However, most American physicists doubted that atomic energy or atomic bombs were realistic possibilities. No official U.S. atomic energy project existed. Leo Szilard was profoundly disturbed by the lack of American action. If atomic bombs were possible, as he believed they were, Nazi Germany might gain an unbeatable lead in developing them. It was especially troubling that Germany had stopped the sale of uranium ore from occupied Czechoslovakia. Unable to find official support, and unable to convince Enrico Fermi of the need to continue experiments, Szilard turned to his old friend Albert Einstein...[Continue the Story]
After going thru some links and lots of text I conclude that, Albert Einstein did not directly participate in the invention of the atomic bomb or World War II, but he was inadvertently instrumental in facilitating, respectively, the development and disintegration of both. This letter from Albert Einstein to President Franklin D. Roosevelt led to the Manhattan Engineering District, also known as "The Manhattan Project". This is where early US nuclear development happened, and the nuclear bombs code-named "Little Boy" and "Fat Man" were constructed and dropped over Hiroshima and Nagasaki, Japan on August 6 and August 9, respectively. The Manhattan Project, a national crash program racing to develop atomic weapons before Nazi Germany, was the seed that grew into the modern national laboratory system, which today includes many non-weapons-research laboratories, such as Argonne (a U.S. D.O.E RnD Lab).
Worth a look -