McCarthyism, also known as the Second Red Scare, was the political repression and persecution of left-wing individuals and a campaign spreading fear of alleged communist and Soviet influence on American institutions and of Soviet espionage in the United States during the late 1940s through the 1950s. It was named after the US Senator Joseph McCarthy who spearheaded the campaign but gradually lost public credibility after his accusations were found to be false.
McCarthyism enveloped the US in a period of paranoia and fear with the newly created House Un-American Activities Committee. Thousands of federal employees and politicians were arrested on accusations of being communists. It politically divided the country and labeled any troublesome government workers as communists to be fired.