As a young reporter, Walter Cronkite watched the world shake and crumble around him.

"World War II — you can't beat that for drama," he says.

And it was just the start. For decades, Cronkite would be at the world's transforming events.

He relives them now on PBS' "American Masters," which has an interesting twist: Katie Couric, who narrates this documentary, takes over the CBS job that Cronkite once held.

Cronkite is accustomed to being surrounded by big people. He reported everything from the moon walk to the Kennedy assassinations and the Vietnam War.

Then, in 1981 at 65, he stepped down. "It was entirely my volition," he says in an interview.

He enjoyed himself; "I had just discovered sailing." And he really did spend more time with his wife and kids, he says.

The Cronkites sailed, played tennis and traveled. Still, don't assume he had no regrets.

"Probably 24 hours after I told CBS that I was stepping down at my 65th birthday, I was already regretting it," Cronkite says. "And I regretted it every day since."

That's the view of a lifelong newsman. Cronkite turns 90 on Nov. 4, but retains CBS ties.

He's been in the midst of big news from his World War II days with United Press. During the war, he flew on a B-17 over Germany, landed in a glider in the Netherlands and saw his London apartment bombed. "So I had a pretty good war," he jokes.

One Sunday morning he had rung George, a terribly British sort of butler, for breakfast. Then a bomb hit.

"My front door to my apartment was down into the hallway. And here, crunching through the glass in the hallway, was George ... He was holding up his towel to a lot of blood ... and so help me, there's always been England, he said, 'Did you ring, sir?' "

People admire calmness in a butler — and in an anchorman. Cronkite was so stoic that viewers were startled to see hints of joy at the moon landing and agony at the John F. Kennedy assassination.

"There's no reason that a journalist should deny his or her emotion at a time when ... reasonable people would have some reaction," he says.

Still, he mostly is wary of news people who flash their feelings. "It's a form of editorial that could best be eliminated."

Cronkite controlled his emotions. Susan Lacy, the "American Masters" producer, calls him "reliable, outspoken and courageous, authoritative and influential ... 14 years after (retiring), he was again voted 'the most trusted man in America,' an astounding accomplishment."

Viewers were startled when Cronkite stepped outside his usual mode and delivered what was labeled an editorial comment.

That was in the days when Dick Salant ran CBS News. Cronkite had returned from Vietnam and was doing a documentary.

"The head of CBS News (was) a stickler for not ever giving an editorial opinion," Cronkite said. "And he said, 'We ought to break our own rules, and you ought to say what you think we ought to do in Vietnam, get out or stay or whatever you think.' "

So Walter Cronkite, a man who had seen much warfare, called for the United States to leave Vietnam. That startled many viewers, including Lyndon Johnson.

"Two days after my piece, he announced he was not going to run for re-election. (I feel) he had already made that decision. My piece just kind of was another bullet."