Clark Clifford was born on December 25, 1906, in Fort Scott, Kansas. He received a law degree from Washington University in 1928 and quickly earned a reputation as a successful attorney, specializing in corporate and labor law.

Clifford became an officer in the naval reserve in 1944 and was appointed as an assistant to President Truman’s naval aide, James K. Vardaman, in 1945. In 1946, Clifford replaced Vardaman, but he soon became one of the President’s lead speechwriters and legal advisors. In 1946, he helped Truman formulate a response to the waves of labor strikes across the nation. That same year, he submitted a memo on Soviet policy, written with aide George Elsey and at Truman's request, which painted a dark picture of Soviet behavior. Clifford also played a major role in reversing the administration’s policy on Palestine and became known as the strongest liberal voice within the administration.

Clifford retired from government service in 1950 and returned to practicing law. During the 1960s, he served as a presidential advisor on foreign intelligence. President Johnson appointed him secretary of defense in 1968, a position Clifford used to advocate de-escalation of the war in Vietnam. He retired again in 1969 and returned to practicing law.

During the 1980s, Clifford was indicted on charges of fraud involving his role as head of a banking firm. He battled those charges for several years; they were later dropped on account of his failing health. Clark Clifford died on October 10, 1998.