Palmer Raids: A series of raids conducted in November 1919 and January 1920 by U.S government under Attorney General A. Mitchell Palmer against suspected radicals and anarchists.
Bolshevik Revolution: Also known as Russian Revolution; it led to the rise of the Soviet Union and inspired fear in other countries about the spread of communism.
McCarthyism: A campaign against alleged communists in US government and other institutions carried out under Senator Joseph McCarthy. It was characterized by heightened political repression and a campaign spreading fear of communist influence on American institutions.