June 23

This Day in History

General Interest

Jun 23, 1959:

Klaus Fuchs released

After only nine years in prison, Klaus Fuchs, the German-born Los Alamos scientist whose espionage helped the USSR build their first atomic and hydrogen bombs, is released from a British prison. Fuchs immediately left Britain for communist East Germany, where he resumed his scientific career.

As a student in prewar Germany, Fuchs joined the German Communist Party in 1930 but in 1934 was forced to flee after Nazi leader Adolf Hitler came to power. Settling in Britain, he became a brilliant young scientist and was recruited by the British military after the outbreak of World War II. Despite his communist past, he was granted security clearance. In 1943, Fuchs was sent with other British scientists to the United States to join the top secret U.S. atomic program. Eventually stationed at atomic development headquarters in Los Alamos, New Mexico, Fuchs became an important figure in the program.

Unbeknownst to anyone at Los Alamos, he made contact with a Soviet spy soon after his arrival and offered precise information about the program, including a blueprint of the "Fat Man" atomic bomb later dropped on Nagasaki, Japan, and everything that the Los Alamos scientists knew about the hypothesized hydrogen bomb. After the war, Fuchs returned to England, where he continued his atomic work and Soviet espionage until December 21, 1949, when a British intelligence officer informed the physicist that he was suspected of having given classified nuclear weapons information to the USSR. The discovery of Fuch's espionage came four months after the Soviet Union successfully detonated its first atomic bomb.

Fuchs pleaded guilty and on March 1, 1950, after a two-hour trial, was convicted. By British law he could be sentenced to only 14 years in prison because the USSR was not an official British enemy at the time of his arrest. After nine years, he was released from prison for good behavior and immediately left Britain for communist East Germany. He died in 1988.

The revelation of Fuchs' espionage was a major factor leading to President Harry Truman's approval of massive funding for the development of the hydrogen bomb, a weapon theorized to be hundreds of times more powerful than the atomic bombs dropped on Japan. The first U.S. hydrogen bomb was successfully detonated in 1952. Three years later, the Soviet Union detonated its first hydrogen bomb on the same principle of radiation implosion.

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