A term coined in 1950, McCarthyism described the escapades of Republican Senator Joseph R. McCarthy of Wisconsin (1908–1957). It was later applied to the broader excesses that characterized anti-Communism in America during the Cold War (1946–1991). McCarthy won notoriety by charging that federal government employees, especially in the State Department, served the interests of the Soviet Union. To critics McCarthyism suggested wild, often baseless and shifting charges of Communist Party membership or sympathy for Communist objectives or the USSR, made against one's political opponents. To McCarthy and his admirers, it meant "Americanism with its sleeves rolled up." The more negative connotation eventually prevailed, but only after McCarthy held the spotlight and defined the nation's political debate for five years.

In his heyday, McCarthy's charges helped explain to many Americans the adverse turn the Cold War took at mid-century and the nation's seeming inability to enjoy the fruits of victory won in...