In early 1953, the 26-year-old Cohn was hired as chief counsel to [Joseph R. McCarthy]'s Senate Permanent Subcommittee on Investigations, then at its height. For the next two years, Cohn later claimed, he was the "savvy" behind McCarthy's wide-ranging and often unfounded attacks on alleged subversives in the U.S. government and military.
Millions of Americans watched the real-life TV drama as McCarthy and Cohn tangled with top Army officials, trading bitter charges and accusations. Army counsel John G. Adams testified that Cohn had threatened to "wreck the Army." Army special counsel Joseph N. Welch also accused Cohn of doctoring a photo that was introduced as evidence.
Cohn and McCarthy in turn charged the Army with "coddling communists" and hiding "sexual deviates." Badgering witnesses and railing against "Fifth Amendment communists," Cohn accused Army officials of holding [G. David Schine] hostage as "blackmail" to stop McCarthy's probes of alleged subversives at the Army's Signal Center at Ft. Monmouth, N.J.