These are final days. The Vietnam War is winding down to its inevitable conclusion, and night 9 of Ken Burns’ epic, eye-opening documentary series opens with no voiceover — just images of anti-war demonstrations to the strains of The Youngbloods’ “Get Together” (“C’mon people now, smile on your brother/Ev’rybody get together, try to love one another right now”).

So much of The Vietnam War is harrowing and hard to watch, as it should be, but in the end, it’s these soaring grace notes that may be the easiest to remember.

Tonight’s two-hour installment — the last chapter before The Vietnam War’s final act Thursday —revolves around, as the title “A Disrespectful Loyalty” states, a divided nation on the home front.

Former Marine Karl Marlantes, one of the first voices of The Vietnam War’s opening night, recalls being picked up at Travis Air Force Base by his brother, on his return from Vietnam, and having obscenities shouted at him while protestors pounded on his car with wooden signs.

“That was my welcome home to America,” Marlantes says pensively, in “A Disrespectful Loyalty’s” opening moments. “I was just stunned. I’ve never felt any anger toward people who were war protestors. It’s a legitimate political stance. For people who descended into that, I think that they were really wrong. It was just, just heartbreak. ‘Why are you doing this? You don’t know who I am.’ And it happened over and over.”

Despite the protests, despite the shootings at Kent State, despite the growing feeling — both in Vietnam and back home — that the war was unwinnable, President Richard Nixon’s hold on what he called “the great silent majority” held firm. This is the scene “A Disrespectful Loyalty” opens on. Over the next two hours, Burns and his co-director Lynn Novick will show how attitudes changed and the worm turned.

“A Disrespectful Loyalty” reminds us, too — just five minutes in — how, as late as May 1970, the late-night TV newscasts were still reporting the casualty rate as if it were an NFL score. If “the other side” had lost 11,349 combatants’ lives and America lost no more than several hundred, the reasoning went, how could the side with the most points on the scoreboard possibly be said to be in a losing situation?

Nixon, as with Lyndon Johnson before him, became increasingly convinced that the anti-war movement was being directed by “foreign players” from abroad — in Hanoi, Beijing, and Moscow.

In January 1971, even as Archie Bunker started to appear each week in Norman Lear’s seminal TV satire All in the Family — one of the most popular sitcoms of its day — and fulminated against “the Commies, the pinkos, the hippies, and the long-hairs” and railed against his lazy, shiftless, good-for-nothing, live-in son-in-law Michael Stivic, “Meathead,” the public mood in the real world was changing.

Nixon took on a siege mentality. It was becoming “us against them.” From Nixon’s point of view, his administration was “us.” He drew his circle closer together, even as the ranks of “them” began to swell. The center would not hold.

The US homeland was as divided as it had ever been, Army veteran Phil Gioia recalls early in the film.

“I think the Vietnam war drove a stake right into the heart of America,” Gioia says quietly. “It polarized the country as it had probably never been polarized since before the Civil War.

“And unfortunately we’ve never moved really far away from that. And we never recovered.”

At first, the US Senate and Congress tried to leave the war to an increasingly corrupt, inept government in Saigon. Over the next two hours, Burns and Novick reveal a steadily deteriorating situation — Nixon’s assertion, “live on tape” as it were, that, “we must declare victory, no matter the outcome;” a GI’s in-country admission that “killing for peace just doesn’t make sense;” how one-in-four enlisted men in Vietnam used marijuana regularly, “but almost never in combat,” according to a military report, and heroin was “cheap, pure and everywhere.”

That’s only the beginning. “A Disrespectful Loyalty” lays bare how one top US commander admitted, “I need to get this army home, so I can save it.” It holds a withering lens to the war-crimes trial of Lt. William Calley and the controversy that followed the verdict and Nixon’s post-sentencing intervention; the mistreatment of American POWs in North Vietnam — tortured and forced to make statements against US involvement in the war; and, toward the end of the night’s program, the back story behind AP photographer Nick Ut’s harrowing image of nine-year-old Phan Thi Kim Phuc running naked down a road after being severely burned on her back by a South Vietnamese napalm attack. That one image, it’s said, did more to change public perception of the war back home than any other single image from the war.

Much has been made of overused songs from the era in today’s movies and TV shows, used so often that they’ve become a cliché.

It’s hard to argue, though, with Burns and Novick’s choice of the Stones’ classic “Gimme Shelter” as the backdrop for the April 1971 protest in Washington, DC by Vietnam Veterans Against the War, with their banners proclaiming, “Veterans for peace.”

It was one thing to accuse war protestors of being Commies, hippies, pinkos, and long-hairs — quite another to belittle and demean veterans who’d actually fought in the war and had seen their friends and colleagues blown to pieces. And for what?

“Vets taking care of vets,” a visibly emotional helicopter crew chief Ron Ferrizzi explains in the film.  “We were generals in our own way. We weren’t joining anything. We became something.”

Ex-Marine John Musgrave, who writer Ed Bark of this parish described in a Sept. 15 essay as the representative heart and soul of The Vietnam War’s witnesses to history, says that while he was proud to serve in the Navy — with the 1st Battalion 9th Marines — he was first and foremost a citizen of the United States of America.

“And being a citizen, I have certain responsibilities,” Musgrave says, “Gimme Shelter” playing softly on the song score.

“And the largest of those responsibilities is standing up and saying no when it’s doing something that you think is not in this nation’s best interest. That is the most important job that every citizen has.”

There is so much about “A Disrespectful Loyalty” that is wrenching and heart-rending, from John Kerry’s defiant testimony at the Senate Foreign Relations Committee Fulbright Hearings in April 1971 to the iconic, still-moving photo of released POW Lt. Col. Robert L. Stirm (right) returning home and being swamped by his adoring family at Travis Air Force Base, in March 1973.

What really makes “A Disrespectful Loyalty” a high watermark in The Vietnam War’s 18-hour running time, though, is the lessons it offers for today.

In a Sept. 19 op-ed piece for the UK Guardian by the Institute of War and Peace Reporting’s Alan Davis, about the crisis facing Myanmar’s leader Aung San Suu Kyi, Davis notes that a national leader in times of crisis must find a way to balance a multitude of competing interests and factions. That reasoning applies to Nixon and Johnson, as well.

There’s a lesson to be learned, though, Davis adds — a lesson Burn and Novick underscore in virtually every frame of The Vietnam War.

And that is that we cannot afford to rely on simple narratives.

To do so, the film argues, is to risk being unprepared for often messy realities.

TV Worth Watching will preview the concluding episode “Episode 10: The Weight of Memory (March 1973 - Onward)” Thursday. The Vietnam War airs on PBS at 8 p.m ET. Check your local listings.