There will be scores of community talk-backs associated with the Ken Burns-Lynn Novick opus The Vietnam War that starts Sunday on PBS.

Perhaps none will be as prestigious as the one this week at the Kennedy Center, that featured three Vietnam veterans that rose to heights in the government. There, Sen. John McCain, former Secretary of State John Kerry (below) and former Secretary of Defense Chuck Hagel (below) joined the filmmakers and journalist Martha Raddatz on stage to discuss the film and the lessons of the war.

Both McCain and Kerry are close friends of Burns, and both had dramatic stories that are a part of the 18-hour documentary that will run over two weeks and with any luck will spark new assessment on what it all meant.

McCain (left) was a POW in North Vietnam from 1967 to 1973; Kerry was a decorated Naval officer who famously threw his medals over the White House fence and testified against the war as a member of the Vietnam Veterans Against the War.

Both stories are told in the documentary, but interviews with the men are not part of it — extending what Novick called their reliance not on historians or officials, but soldiers and first-hand witnesses (though they could have qualified as that).

More than that, the two were their respective party’s nominees for President of the United States in what were ultimately losing campaigns in 2004 and 2008.

To see them bridge any political differences, in support of the epic film about the war that affected them so deeply, was a testimony to the filmmaking of Burns and Novick (though neither indicated that they had seen the whole thing yet).

In a time of deep national division, Burns said the Vietnam War caused the greatest division in the country since the Civil War, and now, more than 40 years later, its divisions could be healed somewhat by the breadth of the film, which begins with the century-old colonization of Vietnam by countries before U.S. involvement and ends with the rift and healing caused by the Vietnam Veterans’ War Memorial, the Maya Lyn edifice that was paid for entirely by veterans’ contributions.

Indeed, The Vietnam War includes a lot of insightful interviews with former North Vietnamese fighters and ex-Viet Cong, to whom the long conflict was known as the American War.

And to begin the Kennedy Center event, Burns made the bold move of following the requisite applause for the Vietnam War veterans present to stand, by also asking to stand those who had been Vietnam War protesters. It did seem like a step forward to stand amid the warriors on both sides and nod at the other gray hairs, to acknowledge bygone struggles.

“I couldn’t tell the difference,” Burns said.

Forty-two years after the fall of Saigon, he said, there still was no one, single truth about the war.

That may have been why it required 18 hours to show so many shades of nuance. And he threatened at first to lock the doors to show it all. “You’ll be getting out about 2 p.m. tomorrow if we don’t take bathroom breaks.”

Instead, a 45-minute version showed six different clips from the piece.

McCain said it’s the right time to tell the story, “particularly since we are in such conflict in the world today.” And he paused to talk about how important it was for him and Kerry to begin talking, while on a senator’s flight to Baghdad, about how to normalize the country’s relations with Vietnam. That “contributed significantly to the healing process that goes on to this day,” he said. “I’m proud of the work we did together.”

“We wanted to get to the point where we would talk about Vietnam as a country, not as a war,” Kerry said.

Hagel, a former senator from Nebraska who served as Obama’s Secretary of Defense, called the film the “most compelling, most comprehensive, honest telling of this story” which he said would have a big impact.

“It’s important to see the consequences of our decisions,” Hagel said.

McCain was struck in what he’s seen of the film of “how young they all were - 18-, 19-, 20-year-old kids who had no idea what they were getting into. Their leaders didn’t lead.”

Usually a panel of that caliber would be the climax of such an event, but because Bank of America was a leading sponsor, its CEO Brian Moynihan got to have the last word, introducing the Lumineers, who played a flat-footed version of Bob Dylan’s “Subterranean Homesick Blues” (which may not even be in the film; it’s certainly not on the soundtrack album).

Moynihan also got into the act of making the Vietnam veterans stand for applause. But, indicating the nation’s rift may still be lingering, he skipped any such recognition for past protesters.

The Vietnam War airs on PBS Sundays through Thursdays Sept. 17-21 and 24-28 at 8 p.m. ET, repeating each night at 10 p.m. Check local listings.

The first five episodes will be available for streaming on Sept. 17 on PBS apps and at pbs.org — in English, Spanish, and Vietnamese language versions. The concluding five will stream starting Sept. 24.

From Oct. 3 to Nov. 28, the series will re-air weekly on Tuesday nights on PBS.