Before he showed half a dozen choice clips from his 10-part, 18-hour film, which premieres Sunday, the director asked everyone who served in the military during the war to stand so they could be recognized.

John McCain and John Kerry were among those who rose, along with other famous veterans like Bob Kerrey and Mike Mullen.

Burns then asked anyone who protested Vietnam to also stand. Dozens did.

“I couldn’t tell the difference,” the director said, referring to the two groups.

The veterans, including McCain, joined the audience in applauding the antiwar demonstrators.

That moment set a tone of reconciliation and harmony for a discussion about one of the darkest and most divisive chapters in American history.