NEW YORK — Rory Kennedy was born three months after her father, Robert F. Kennedy, was assassinated while campaigning for president in 1968, largely on an anti-Vietnam War platform. She was just 7 years old when Saigon fell into the hands of the North Vietnamese. And it is the losses and lessons of that war — specifically the harrowing, little-known tale of its very end — that Kennedy has chosen for her latest documentary, “Last Days in Vietnam.”
Rory Elizabeth Katherine Kennedy, the youngest of Bobby and Ethel’s 11 children, says she grew up fascinated by the war.
“Vietnam was in the ether of my childhood,” Kennedy said in a recent interview in New York, where she was promoting her film, which opens Friday in Boston. “It’s a seminal event in the nation’s history, and there’s a lot of lessons we can continue to learn from Vietnam.”
At 45, Kennedy has produced or directed numerous documentaries, including many on social issues, from AIDS to Appalachia to Abu Ghraib. She began developing the idea for the new film as the United States was withdrawing from Iraq and Afghanistan.
“I thought there were parallels to be drawn,” she said, gesturing animatedly. “I felt the connection with Vietnam much more profoundly, given what happened in Iraq. I felt there was a timeliness to it, and I was more aware of the fact that we’re coming up on the 40th anniversary of the fall of Saigon.”
She hopes Vietnam’s lessons are heeded today.
“With ISIS going into Syria, to me one of the lessons is, should we enter a war even if horrible things are happening? What is our exit strategy? How will it affect people on the ground? As we’re considering entering these wars I hope [the film] helps us answer those questions of what the endgame is and how we get out.”
She paused. “And I don’t feel those questions have been answered yet.”
The documentary focuses on Saigon in the waning days of April 1975, when US officials began a final evacuation as North Vietnamese troops barreled southward. The film asks — and answers — “the burning question: Who goes, and who gets left behind?”
Most at risk were the thousands of South Vietnamese soldiers and civilians who had worked with the Americans, as well as their families. But White House orders were to evacuate US citizens only. Those who defied the orders risked treason charges.
The film unfolds in a series of interviews with figures from that era, including 91-year-old Henry Kissinger, who acknowledges “another horrendous screwup” as 11 Marine guards were nearly left behind.
Kennedy has also found footage never seen before, and she weaves it together to create a complex, compelling chronicle of those last chaotic hours of April 29.
What surprised her most were the unsung heroes who emerged from her research.
“At this dark moment in American history, there’s these extraordinary stories of Americans doing the right thing,” she said, blinking her eyes several times before adding, “I still get welled up a bit.”
‘I certainly didn’t have the expectation that it would be as heart-stopping, as poignant, and as beautifully crafted as it turned out. I sat in the audience and cried half the time.’
One of them is Stuart Herrington, an Army captain in Vietnam who at first did not want to be involved with the film. Herrington had written a couple of books on the war in the early 1980s, had been in other documentaries about Vietnam, and was skeptical.
“Did I really want to talk about this again?” said Herrington, now a retired colonel who lives in Carlsbad, Calif. “It would be another ‘woe is me’ gnashing of teeth of what we did wrong.”
But he says he was impressed by Kennedy and her staff. “This wasn’t going to be politically oriented or ideological, so I decided to do it,” he said.
When he saw the film at the Sundance Film Festival this year, he was stunned: “I certainly didn’t have the expectation that it would be as heart-stopping, as poignant, and as beautifully crafted as it turned out. I sat in the audience and cried half the time.”
Though he spent nearly four years in Vietnam as a military intelligence officer, Herrington says even he learned new details from Kennedy’s film. “She’s found these little shadow dramas that took place, and she actually manages to make an uplifting film out of the tragedy,” he said.
Binh Pho was a 19-year-old college student left on the embassy roof when the last copter took off. He was imprisoned by the North Vietnamese, but escaped in 1978. In 1979, he came to the United States and now lives in Chicago, where he is an artist. His presence gives the film the perspective of someone left behind.
“I have to say it was very emotional watching the film,” Pho said. “I got chills, and it brought back the memories.”
Until he saw the documentary, he says, he didn’t know why he was not rescued. “I heard a rumor that a helicopter got shot down,” he said. “But now I know an order was given to abort the mission because the pilot got so tired of flying that he fell asleep.”
Kennedy says she was attracted to Herrington’s heroism “and his profound sadness of leaving people behind. [I hope] to have the audience feel what I feel, which is to take the load off Herrington and put it on us.”
Us? “I think we’re all somewhat implicated,” she explained. “I think for those of us against the war, we just wanted to get out. I don’t think we comprehended what was going to happen. And for the prowar people, that it escalated so much. I think these folks are also implicated.”
Kennedy’s husband, Mark Bailey, co-wrote “Last Days in Vietnam” and several of her other films. The couple, who live near Los Angeles, have three children.
It was their 1999 Hyannis Port wedding that her cousin John F. Kennedy Jr. was flying to when his plane crashed off Martha’s Vineyard, killing him, his wife, Carolyn Bessette, and her sister.
Two of Rory Kennedy’s brothers are dead, David from a drug overdose and Michael in a skiing accident, his head cradled in her arms.
Have her personal losses affected her filmmaking? “I can certainly relate to other people going through difficult times, and a heck of a lot worse than what I’ve experienced,” she said. “But I think perhaps because I have experienced a lot of sadness in my life, I try to have a little bit more of an open heart.”
The film opens in Boston Friday. A special screening will be held at the Kendall Square Cinema on Thursday, part of a documentary series sponsored by the Globe.Bella English can be reached at firstname.lastname@example.org.