In September 1962, Attorney General Robert Kennedy asked Nicholas Katzenbach to fly to Mississippi to attend to a little civil rights matter.

In his new memoir, “Some of It Was Fun: Working with RFK and JFK,” Katzenbach recalls that he agreed easily and asked, “What do you want me to do?”

“‘Nothing much,’ Kennedy said. ‘Just get Meredith registered and keep the peace.’”

As history records, the registration of James Meredith as the first African-American student to attend the University of Mississippi was anything but “nothing much.”

Katzenbach’s role in keeping the White House informed of the volatile situation in the South is one of the compelling stories that the former attorney general tells in his new book.

Katzenbach, 86, served under former Attorney General Robert Kennedy in the Department of Justice and succeeded him when Kennedy won election to the Senate. Later, he became undersecretary of State.

Katzenbach’s memoir focuses narrowly on his career in government from 1961 to 1968. In fact, the memoir rarely mentions his wife, Lydia, and four children (among them novelist John Katzenbach). At the beginning of his story, Katzenbach is on leave from his teaching position at the University of Chicago Law School on a fellowship in Geneva, where he followed Kennedy’s election from a distance and felt compelled to find a way to join his administration.

He doesn’t elaborate on his transition from the State Department to IBM, which he joined as vice president and general counsel in 1969.

Katzenbach’s most important contribution to government may have come before he became attorney general. As deputy attorney general, Katzenbach offered advice to President Kennedy and became well-versed in the politics of civil rights.

One of the department’s chief concerns was school desegregation cases the Legal Defense Fund brought in the South. One such case led to the admission of James Meredith at the University of Mississippi.

On a Sunday afternoon in September 1962, Robert Kennedy abruptly asked Katzenbach to fly to Oxford, Miss.

What started as a deceptively simple assignment exploded into an overnight stakeout. Federal marshals, members of the National Guard, troops and increasing numbers of highway patrolmen arrived to protect Meredith and prevent violence, facing off against an angry mob. Katzenbach called the White House collect from a pay phone early in the night and kept that line open through the night, relaying updates and questions to the president and the attorney general. When those in D.C. were told that troops were at the airport, Katzenbach told them they actually were not. When marshals asked that Robert Kennedy give them permission to use their handguns, Katzenbach relayed Kennedy’s refusal. He negotiated to keep reluctant local patrolmen on the scene as long as possible and authorized the use of tear gas.

Ultimately, Meredith was registered for classes and endured four years with military protection to graduate, “a brave man who received perhaps the most expensive public education in our history,” as Katzenbach wrote. Katzenbach later helped enroll black students at the University of Alabama.

After JFK was assassinated in 1963, the atmosphere of the Justice Department changed, Katzenbach remembers. What had been a dynamic agency run by the president’s brother became a less energetic agency run by a grief-stricken man with lingering suspicion of then-President Lyndon Johnson.

When Kennedy left the Justice Department, Katzenbach became acting attorney general and was surprised when Johnson made the promotion of a Kennedy loyalist permanent after he was sworn in as president.

He served as attorney general until 1966. During that time, he ushered the Voting Rights Act through Congress, created the Crime Commission and oversaw passage of the immigration act. Yet Katzenbach began to feel burned out, so when Johnson asked for his recommendation for undersecretary of state, Katzenbach offered a surprise suggestion: himself.

Katzenbach transitioned to undersecretary of State and began to feel his way around the country’s almost single-minded foreign policy.

“Vietnam, Vietnam, Vietnam,” begins Chapter 26 of Katzenbach’s book. “It got in the way of everything: LBJ’s Great Society programs, our African initiatives, the Middle East, everything.”

Although now Katzenbach says that Johnson may have been more effective domestically than Presidents Franklin Roosevelt and Harry Truman combined, at the time, the conflict in Vietnam overshadowed any of his accomplishments. Katzenbach devoted much of his time at State to highlighting relationships with African countries and trying to forge a consensus for withdrawal from Vietnam.

That effort failed while he was in office, but in the end, Katzenbach feels he did all he could. “I would have liked to solve the problem in Vietnam, but I didn’t and I don’t think I could have,” he said.