errorized London. Of greater historical significance, though, was the construction of the atomic bomb. As soon as nuclear fission was discovered in Europe, it became apparent that if a way could be found to release its energy in a bomb, the course of the war would be altered. In America a number of physicists, many of European origin, worried that Hitler might acquire such a weapon and persuaded the normally pacifistic Albert Einstein to warn President Franklin D. Roosevelt. In an urgent letter dated August 2, 1939, he explained the danger by writing: "It is conceivable...that extremely powerful bombs of a new type may thus be constructed." Einstein's letter did not have an immediate effect, but eventually helped to persuade the United States to begin the monumental task of building an atom bomb. The man chosen to direct the project was the theoretical physicist Robert Oppenheimer. Although he had no industrial or even experimental experience, he proved to be a remarkably effective leader. His team on a remote mesa in New Mexico, and smaller groups in other secret laboratories, included most of the nation's best physicists. By the force of his towering intellect Oppenheimer managed to unite this diverse group in a common effort to design and build a bomb, and to test it successfully in July 1945. By then, Germany had already surrendered, but its ally Japan was still at war. In August 1945, two atomic bombs dropped on the Japanese cities of Hiroshima and Nagasaki contributed to a quick end of World War II. Their chief legacy, however, was to be felt for a long time. For almost half a century the Cold War's nuclear stand-off between the United States and the Soviet Union held the world in its grip. In the united States the successful conclusion of World War II inspired a heady sense of optimism and self-confidence which was further bolstered by the end of the Great Depression. Renewed prosperity, in turn, allowed America to c...
