Free Fifties by David Halberstam

Nothing, he noted, had really changed about the Super since 1942; as far as he was concerned it was still a weapon of the unknown. But there had been “a very great change in the climate of opinion.” Pressure was beginning to mount from those scientists with whom he disagreed and who favored the Super: “On the other hand two experienced promoters have been at work, i.e., Ernest Lawrence and Edward Teller. The project has long been dear to Teller’s heart and Ernest has convinced himself that we must learn from Operation Joe that the Russians will soon do the Super, and that we had better beat them to it.” The congressional attitude, Oppenheimer added, seemed to be, “we must have a Super, and we must have it fast.”
    The person who would have to make the decision, of course, was Truman, and his room to maneuver was steadily shrinking. Beginning in September 1949, a scenario was being played out in England that would further force Truman’s hand. In a time when there were endless accusations about who was a member of the Communist party, who was a fellow traveler, and who was an actual honest-to-God spy, the case of Klaus Fuchs was special. It received far less attention than other, more celebrated, cases in which the actual amount of damage from spying remained in doubt. Because the British were embarrassed by the Fuchs case and wanted to rush it through their legal system, the trial lasted only an hour and a half. Because Fuchs was a talented physicist, with every high-level clearance imaginable, it was appallingly clear that all work at Los Alamos through 1946 had been completely compromised. There were even fears that Fuchs might have seriously hindered America’s progress on the H bomb.
    Fuchs was a German émigré, living in England. An enemy alienat the time the war broke out, he was briefly interned in Britain as such. Under enemy-alien status, as his biographer Robert Chadwell Williams has pointed out, he could not own a car or join a British Civil Defense team, but he could in time work on the most secret aspects of atomic physics.
    Fuchs came from a long line of Quaker ministers in Germany. Once merely socialist and pacifist, his family was deeply affected by the terrible outcome of World War One and the rise of Hitler. For them and others like them, the Communists seemed to represent the only answer to the Nazis. Fuchs’s mother committed suicide in 1931, and later so did a sister, Elisabeth. Fuchs was wanted by the Gestapo as a member of the Communist party, and he left the country—on orders from the German Communist party—to continue his studies elsewhere. He arrived in England in the winter of 1933–34, one of thousands already fleeing Hitler. A good deal was known in England about his earlier political radicalism, but no one moved on it or checked out the preliminary reports very thoroughly, and he was repeatedly cleared for high-level work by British intelligence. Events, after all, were surging ahead, and soon the Soviet Union was to be England’s ally. In May 1941, Fuchs began to work on British aspects of the atomic bomb; within weeks he had volunteered to pass on top-secret information to the Russians. No one from the Party had pressured him to do this—he saw it as his duty. In June 1942 he became a British citizen; in mid-1944, he came over to America with a number of British scientists.
    He was the quiet man of Los Alamos. Elfriede Segre would watch him go by, a pallid bachelor, slightly hunched, so sad, so alone, caught in a world of his own, and thought of him as “Poverino—the Pitiful One.” Stanislaw Ulam, the brilliant mathematician, noted later that Fuchs never liked to talk about his past or why he had left Germany. Some thought him a man overwhelmed by his own sorrow. He was considered a good physicist, not of the very top rank, but unusually hardworking. By late 1944 he was working in the most sensitive part of the institute, the bomb design and assembly