IN THE 35 YEARS before the birth of the modern civil rights movement that he helped to spearhead, A. Philip Randolph was the most prominent—and the most effective—African American leader in the United States. His persuasiveness and adroit use of political pressure on two presidents led to creation of the first federal civil rights enforcement body as well as full integration of the armed forces.

The son of a Florida minister who impressed on his sons a love of the classics and an appreciation for black heroes of history, Randolph moved to New York City for a college education and in hopes of becoming an actor. But he forged a friendship with Chandler Owen, a law student and a socialist, and abandoned the stage for a ...