FAMOUS SPY NUMBER FIVE
Spied For: The Soviet Union
Klaus Fuchs was a German-born theoretical physicist who worked on the atom bomb project in Los Alamos. He was responsible for theoretical calculations relating to the first fission weapons and early models of the hydrogen bomb. He attended university in Germany and became involved with the Communist Party of Germany. After a run-in with the newly installed Nazi government, he fled to England where he earned his PhD in physics and worked on the British atomic bomb project.
While he was working for the British, he started giving information to the Soviets. He thought they had the right to know what the British and the Americans were developing. In 1943 he transferred to the United States to work on the Manhattan project.
For two years he passed on the theoretical plans for building a hydrogen bomb. He gave them data on the production of uranium 235, which allowed the Soviets to determine the number of bombs possessed by the United States. When he returned to the UK in 1946, he was interrogated, tried and sentenced to fourteen years in prison. This was the maximum penalty under British law for passing military secrets to a friendly nation. He was released after nine years and moved to Germany.