Most instense outbreak of national alarm, began in 1919. Success of communists in Russia, American radicals embracing communism followed by a series of mail bombings frightened Americans. Attorney General A. MItchell Palmer led effort to deport aliens without due processs, with widespread support. Did not last long as some Americans came to their senses. Sacco/Vanzetti trial demonstrated anti-foreign feeling in 20's. Accused of armed robbery & murder, had alibis. "Those anarchists bastards". Sentenced to death and executed.