When America initiated the Manhattan Project it relied on the talents of many brilliant scientists who were often eccentric and some of them politically compromised, none more so that the atomic spy Klaus Fuchs.
Fuchs was born in Germany in 1911, the third of four children of Lutheran pastor Emil Fuchs. His father held strong left wing views as a member Social Democratic Party of Germany (SPD) and heavily influenced the younger Fuchs‘ political views.
He too joined the student branch of the SPD when he entered the University of Leipzig in 1930, but was expelled during the presidential election of 1932 when he spoke in favour of the Communist Party (KPD) candidate while the SPD officially supported Paul von Hindenburg in the hope of preventing Hitler gaining power.
Fuchs and his brother became active speakers at KPD meetings and occasionally attempted to disrupt Nazi party meetings. Hitler became chancellor in 1933 and while on his way to Berlin to speak at a KPD meeting, Fuchs read newspaper reports about the Reichstag fire and correctly assumed that the blame would be laid squarely on the opposition parties. It was then that he decided to flee Germany.
The British couple Ronald and Jessie Gunn invited him to stay with them in Somerset. Jessie was a member of the Wills family and an heir to the Imperial Tobacco company and she used her influence at Bristol University to secure Fuchs a job as a research assistant and he earned his PhD in physics there in 1937. He then went on to work with the physicist and fellow German refugee Max Born at Edinburgh University.
Fuchs applied for British citizenship in 1939 but war broke out before it was processed and he was arrested and interned, first in the Isle of Man and then in Canada. Family and friends vouched for his anti-Nazi credentials and he was released on Christmas Day 1940 and returned to Edinburgh.
He was approached to work on the Tube Alloys programme, the code name for the British and Canadian atomic bomb project that preceded Manhattan. Little did the authorities realise that Fuchs believed that Britain and America were deliberately withholding information from their Russian ally in the hope that they and Germany would destroy each other and it was this belief that persuaded him to become a Soviet spy.
In late 1943, Fuchs was transferred to Columbia University to work on the means of uranium enrichment for the Manhattan Project, and in 1944 at the Los Alamos Laboratory. And all the time he was passing information to his NKVD handlers.
Fuchs remained a valued member of the Los Alamos team post-war and became a double spy following the US Atomic Energy Act of 1946 which prohibited the sharing of nuclear research with any foreign country, including Britain. As well as passing information to the Russians, Fuchs did the same for his colleagues in Britain.
He returned to Britain in 1946 to become head of the Theoretical Physics Division at the Atomic Energy Research Establishment at Harwell and between 1947 and 1949 he gave his Russian handlers the principal theoretical outline for creating a hydrogen bomb.
Fuchs was finally unmasked by the Verona Project, the US counterintelligence programme to decrypt Soviet communications. In January 1950, he voluntarily confessed that he was a spy and this directly lead to the decision by the US to cancel its agreement to provide Britain with American made nuclear weapons.
After a trial lasting just ninety minutes, Fuchs was sentenced to fourteen years imprisonment and later stripped of his British citizenship. He was released in 1959 and emigrated to East Germany. There he helped Chinese physicists to develop their country’s first atomic bomb.
Fuchs continued his scientific career and achieved considerable prominence. He was elected to the Academy of Sciences and the SEDcentral committee and was later appointed deputy director of the Institute for Nuclear Research in Rossendorf, where he served until he retired in 1979. He received the Patriotic Order of Merit, the Order of Karl Marx and the National Prize of East Germany. He died in Berlin in January 1988.