Reviewer: ROBERT WILLSON

In July 1945 three world leaders met at Potsdam, just outside the rubble of Berlin. They were the leaders of Great Britain, the United States of America, and the Soviet Union. Nazi Germany had been defeated but Japan was still fighting.

The newly elected President of the United States, Harry S. Truman, planned to tell Joseph Stalin about a new and terrible weapon, the atomic bomb, that was now in the hands of the United States. But he waited until he had received news of the successful testing of the weapon at Los Alamos, New Mexico, and until he knew that the bomb would be ready to use against Japan. The weapon was code-named Little Boy. A second atomic bomb,  named Fat Man, would be ready a few days later.

This was the culmination of years of work by thousands of British and United States scientists, under the direction of Robert Oppenheimer, in the Manhattan Project. They had a single goal: to build an atomic bomb. But one of those scientists, a brilliant theoretical physicist named Klaus Fuchs, was a dedicated communist. Fuchs not only greatly contributed to the project. He made sure that all the information he obtained was passed to the Soviet Union.

Truman believed the demonstration of the horrifying power of this weapon would capture the attention of Joseph Stalin far more than claims at a conference. Truman was wrong. He mentioned to Stalin that the US had a new weapon of “unusual destructive force”. Stalin showed no special interest and we now know why.  The Soviet Union was already engaged in the same research project, greatly assisted by a group of western spies, the most notable of whom was Fuchs, the subject of this absorbing biography, The Spy Who Changed the World.

It is generally agreed that the Soviet Union would have eventually  developed the bomb anyway, but the activities of spies such as Fuchs shortened the time by more than a year. Fuchs was the spy who most seriously damaged security for the Allies. He had been working in Britain and the revelation of his long career of espionage led to the US cutting Britain out of nuclear research and forcing it to pioneer its own nuclear program in the 1950’s. This included the testing of nuclear weapons in the Australian desert. The perfidious treachery of Fuchs cast a long shadow.

Klaus Fuchs was born in December 1911, the son of a clergyman who was professor of theology at the University of Leipzig, and the young Fuchs studied at the same university. But he soon rejected his family’s Christian heritage and joined the German Communist Party. After the 1933 Reichstag fire Fuchs fled to England where he received doctorates from Bristol University and from Edinburgh University, where he was assistant to Max Born, a German-born theoretical mathematician.

With the outbreak of war in 1939 Fuchs was interned but eventually released and resumed work on the British atomic bomb project. It was at this time that he first began passing data to the Soviet Union and he continued to do so when he transferred to the Manhattan Project in the United States.

The author gives a memorable account of the risks that Fuchs took in the weeks after the bombing of Hiroshima. He drove around in a second-hand Buick with a bundle of papers on the seat beside him, containing the most closely guarded secrets about the weapon that had transformed the United States into the world’s first superpower.  Yet hewas never caught and was able to pass on the documentation to the Soviet Union.

Many of these hour-by-hour details come from the Russian archives, now released since the end of the Soviet Union.

Meanwhile the race inside the Soviet Union to perfect and test a nuclear weapon had continued. The author describes the fear of all involved in this project that, should they fail, would bring down on them a terrible retribution from Stalin. But a successful test in 1949 made the Soviet Union the second nuclear power in the world.

After the war Fuchs returned to Britain and continued to work on British atomic research. In 1950 he voluntarily confessed  to being a spy who had betrayed Britain and the US, and was sentenced to 14 years in prison. After his release Fuchs went immediately to East Germany and continued his scientific research . He died in 1988.