After World War II the United States felt that Communism was a threat that would interfere with national security and the economy. After World War II the world was dominated by two superpowers: the USA and the USSR. The Cold War was a result of this division of power and of the important policy of influence. In this hostile environment the Cold War began. This really began because one superpower saw its interests threatened. They began to support one side; for example in Korea and Vietnam, where the US feared a communist government to take over instead of a democratic one.
The threat of Communism was real to people in America and in many peoples views it needed to be eliminated. That was the whole purpose of the Black list, for the communist threat in America to be revealed and eliminated. It led to many misconceptions about people, and in some cases just a way to take out competition.
Julius and Ethel Rosenberg
During World War II Julius Rosenberg was employed as a civilian inspector for the Army Signal Corps, but was dismissed in 1945 as a result of allegations that he was a member of the Communist Party. He then opened a small machine shop in Manhattan with his brother-in-law, David Greenglass. However, the business did badly and Greenglass left the partnership.
In 1950 Klaus Fuchs, head of the physics department of the British nuclear research centre at Harwell, was arrested and charged with espionage. Fuchs confessed that he had been passing information to the Soviet Union since working on the Manhattan Project during the Second World War. The Manhattan project was the production of nuclear weapons.
The FBI wanted to discover the names of the spies who had worked with Klaus Fuchs while he had been in America.