Nicholas Katzenbach is perhaps best remembered for staring down Gov. George Wallace, the gatekeeper of segregation, in 1963 at the registrar’s office at the University of Alabama. As a deputy attorney general, Katzenbach was as unblinking and determined that moment as he was throughout his remarkable life. Katzenbach, 90, died last Tuesday at his home in Skillman, N.J., according to his wife, Lydia.

When he defied Wallace, he was there to read a presidential proclamation ordering that Vivian Malone and James Hood, two African-Americans, be admitted to the university.

Wallace, unperturbed and equally defiant, uttered the words that echoed his stance: “Segregation now, segregation tomorrow and segregation forever!” Four hours later, after an exchange of statements, Wallace relented and Katzenbach escorted the students to the registrar’s office.

During his tenure as Attorney General Robert Kennedy’s second in charge at the Justice Department, Katzenbach took on J. Edgar Hoover with the same bulldog-like tenacity he offered Wallace, particularly on the issue of wiretapping Dr. Martin Luther King Jr. While Katzenbach and Kennedy agreed to the wiretapping of King’s phone to show that he had no affiliation with the Communist Party, they balked at Hoover’s bugging King’s hotel room to disclose extramarital sexual encounters.

Beyond his prominent role in policy making during the civil rights era, Katzenbach distinguished himself as a war hero, a Rhodes scholar and a law professor. Exemplary of his will and determination was his survival in a Nazi prison camp, where, during nearly a year and a half of captivity, he read some 400 books–learning he used to pass a series of examinations, acting as a substitute for his college education, which was interrupted at 19 when he joined the U.S. Army Air Force.

As attorney general, besides helping to draft and steer civil rights legislation through Congress, Katzenbach defended the 1964 Civil Rights Act before the Supreme Court, winning a 9-0 ruling. In 1965, he had the Justice Department seek a federal court order barring Alabama officials from interfering with the civil rights march from Selma to Montgomery, which was led by King.