PRINCETON, New Jersey (AP) – The walls of Nicholas Katzenbach's library are evidence enough that he has led a full and historic life – pictures signed by Lyndon Johnson and Coretta Scott King, photographs from the Oval Office, a pencil sketch of Robert Kennedy, with an inscription from his widow, Ethel.

A member of Kennedy's famous team at the Justice Department who later became attorney general, a key aide on civil rights who confronted George Wallace before TV cameras and helped pass Johnson's landmark legislation, Katzenbach witnessed and participated in many of the great triumphs and struggles of the 1960s.

Never as famous as the people for whom he worked, he was regarded as smart, honest and selfless, so selfless that many now don't know who he is. About a year and a half ago, Katzenbach decided to tell his story – if only because he had nothing better to do.

"I was bored," says the bald, burly voiced Katzenbach, 86, seated in an armchair on a sunny autumn afternoon, his bright, high-ceilinged home quieted by 50 acres of wildlife. The Bush administration's firings of several US attorneys in 2005-2006 also convinced him that he should write a memoir.

"It was a combination of being bored and being disgusted with the current administration and what they were doing to the Justice Department," he says.

Katzenbach's memoir, 'Some of It Was Fun', covers his eight years in government, from his eagerly joining the Kennedy administration to his weary departure from the Johnson administration, when the most exhausting of decades had left him worn out.

He wasn't an intimate companion of the Kennedys or the Johnsons, but he was a trusted aide who always seemed to be around when history happened – not just civil rights history, but the Bay of Pigs invasion, the Cuban Missile Crisis, the Warren Commission and the Vietnam War.

"He is a central figure in so many of the pivotal episodes of American history of the 1960s," says Robert Caro, who has interviewed Katzenbach for the fourth and final volume of his series of books on Lyndon Johnson. "And he has the ability, which not every participant has, to see the larger implications of their actions."

"Nick has been a truly noble public servant," says historian Sean Wilentz, who praises Katzenbach as a model for a time when government officials were "honest pursuers of justice, without ideological axes to grind''.

Katzenbach, a native of Philadelphia who grew up in Trenton, New Jersey, was born into a political family. His father, Edward L. Katzenbach, was New Jersey's attorney general. His uncle, Frank S. Katzenbach, was the mayor of Trenton whose hopes for becoming governor were stopped by the rise of a Princeton University president named Woodrow Wilson.

Nicholas Katzenbach was just the kind of man the Kennedys valued: educated (Princeton, Yale, Oxford), ambitious, yet practical, and tempered by war. An Army Air Corps navigator, he was shot down by the Nazis and spent two years in prison camp.

For much of the 1950s, Katzenbach was a professor of law, first at Yale, then at the University of Chicago. He was on a leave of absence, in Switzerland, when John F. Kennedy received the Democrats' nomination for president in 1960.

"Kennedy was a junior officer in the Second World War, just as I had been. And it was a really strong pull for young veterans who came back from the Second World War," he says.

Katzenbach phoned fellow Yale alumnus and future Supreme Court justice Byron White and was told to come to Washington. After being interviewed by Robert Kennedy (who addressed him as "Professor Katzenbach"), he was named to head the Justice Department's Office of Legal Counsel.

Robert Kennedy's time as attorney general is now widely praised, but his appointment was initially ridiculed: He was in his mid-30s, impetuous, inexperienced – and the president's brother.

But he recruited prime legal talent, including Katzenbach, White, Burke Marshall and Archibald Cox, and didn't interfere politically. Katzenbach remembers Kennedy as informal, energetic and open-minded, happy to hear anyone's opinion and respectfully demanding of the highest standards.

"The most serious criticism that Bobby Kennedy could ever make was to say, `That's not very satisfactory, is it?' Boy, that just meant you really screwed up. But he never blew up, never lost his temper," Katzenbach says.

"It's very hard to see how that young man grew up as fast as he did, became as mature as he did in so short a period of time. He gained an awful lot of wisdom."

Victor Navasky, whose "Kennedy Justice" is a history of Bobby Kennedy's Justice Department, says Katzenbach was a "reality anchor'', never more weighted than in 1963, when the University of Alabama at Tuscaloosa was ready to admit its first two black students and Gov. George Wallace had vowed to "stand in the schoolhouse door" to stop it.

It was an orchestrated confrontation, with Wallace having signalled privately that he would relent. Someone would have to represent the federal government – Katzenbach. Looking businesslike in a suit and tie, sweating under the Alabama sun, Katzenbach walked up to the school's entrance and handed Wallace a presidential proclamation saying he must obey the law.

With the nation watching on television, including a nervous Robert Kennedy at his office in Washington, Wallace denounced outside interference, while Katzenbach called the governor's tactics a mere "show''. The students were peacefully registered.

"Katzenbach was such a smart person; you had to marvel at his ability to operate within the confines of what diplomacy permits," Navasky says.

Asked to cite his best times in government, Katzenbach mentions the 1964 Civil Rights Act, when Sen. Clair Engle, a California Republican who had twice undergone brain surgery, was carried into the Senate chamber on a stretcher and cast a key vote that helped ensure the bill's passage. The worst day: President John F. Kennedy's assassination in Dallas, November 22, 1963. Katzenbach was at lunch in Washington when he heard the news that Friday afternoon. He had little time to grieve. Vice President Johnson wanted to be sworn in immediately as president. Katzenbach's advice was needed. Did the chief justice of the Supreme Court need to swear in the new president? No, replied Katzenbach, a federal judge could do it. Since no one with Johnson knew the exact oath of office, Katzenbach found a copy of the Constitution and read it over the phone to LBJ aide Jack Valenti. At the time, killing the president wasn't a federal crime, so the case was initially handled by Texas officials. But when suspect Lee Harvey Oswald was shot dead, on national television, conspiracy theories were so strong that Katzenbach suggested that a "blue-ribbon" panel investigate – what eventually became the Warren Commission.

Katzenbach was one of the few officials equally valued by the Kennedy administration and by President Lyndon Johnson, who had a bitter relationship with Robert Kennedy. After Kennedy resigned in 1964 to run for the US Senate, Katzenbach was named acting attorney general, then given the job permanently. He would adjust well from the urbane Kennedy style to the rough, hands-on Johnson approach, thanks in part to his quick, legal instincts

His last two years in Washington were the hardest. With the president's attention increasingly turned to Vietnam, Katzenbach became bored and volunteered to fill an opening as undersecretary of state. He had hoped for a peaceful settlement, and says Johnson wanted the same, but the war only intensified, with no foreseeable end. Katzenbach wanted out, regardless of who was the next president. In 1969, he became general counsel for IBM.

Katzenbach says he needed just a few months to complete 'Some of It Was Fun', working from notes and other documents, and a strong memory, although not so strong that he doesn't acknowledge in the preface that "while I vouch for the substance with confidence, I cannot do the same for the precise words''.

The book's title came from a conversation with his daughter, Mimi. She had read a chapter and commented, "You know, Dad, I think you were enjoying a lot of this."

Well, Katzenbach replied, "Some of it was fun."