At Age 13, Creating the Pentagon Papers. Copies of It, at Least.

“I said, ‘Yes, sure,” the son recalled. Off they went to a Xerox machine that was big, clunky and, by today’s standards, very, very slow.

It was the first time anyone had let the son run such a monster. He was thrilled.

Saying that the father wanted to copy “some papers” is like saying that the Vatican is “a church.” The papers — which the father was smuggling out of his office, a briefcase-full at a time — would become known as the Pentagon Papers, the sprawling, classified history of the Vietnam War. The father was Daniel Ellsberg, a former Defense Department official who by then was deeply discouraged about the conflict.

The son, Robert Ellsberg, may have had a cameo role in history as his father’s helper, but not in the film “The Post,” Steven Spielberg’s drama about the newspaper that played catch-up after another newspaper — The New York Times — broke the story of the Pentagon Papers.

There was no 13-year-old at the Xerox machine in the movie, only grown-ups, but then, there was a lot of copying to be done, Ellsberg’s father put him to work only twice and moviegoers expect edge-of-your-seat action. Old-fashioned Xeroxing — slapping a single sheet of paper on a glass plate, pushing a button, waiting for the copy to print out, then doing it all over again with the next page — is anything but.

“It’s funny about the film,” Ellsberg said. “At one of the premieres, Steven Spielberg said there were things we would have liked to have put in this film that nobody would have believed, like that Ellsberg brought his kids to help copy the papers.”

Ellsberg knows that because he read it somewhere — no VIP screenings for him. He paid for his own ticket to see “The Post” at a theater in Pleasantville, New York. No one in the audience realized that the fingerprints on someone’s bucket of popcorn would have matched fingerprints the FBI found on the Pentagon Papers. As he dryly put it, “I didn’t introduce myself.”

He has been happy not being in the limelight or his father’s shadow — he said that for years, he did not want to be remembered as “Robert Ellsberg, son of Daniel Ellsberg.”

“I wanted to be my own kind of person,” he said, adding that he had never given a long interview until we spoke last week.

But “The Post” has people calling. The Harvard Divinity School posted a question-and-answer session with Ellsberg on its website. And on Saturday, he will take part in a conversation at the New-York Historical Society that it says is intended “to help young visitors better understand one of the biggest scandals of the 20th century and the role that one kid played in it.”

So, about that kid, who is now 62.

“I don’t think he imagined there was much risk involved for me as a teenager,” Robert Ellsberg said of his father. But his father was clear that he himself faced risks: “He imagined he might end up going to prison, maybe for the rest of his life.”

And there was something besides conscience and principle: “He had this feeling — what did he have to leave, to pass on to his son, the circumstances under which one might take great risks for something you believe is right.”

It was an irresistible pitch, and as Robert Ellsberg remembers it, his father said, “Let’s go do it right now.”

The Xerox machine was at an advertising agency where Daniel Ellsberg knew the owner. On the way in, Robert Ellsberg said, they set off the burglar alarm, but the police officers who responded believed the Ellsbergs when they said they had permission to be there — and did not notice what they were copying.

On Robert Ellsberg’s only other turn at the Xerox machine, they took his younger sister Mary along on what began as a divorced-dad outing with the kids.

“I think this was not planned, exactly, but there was something he wanted to copy right away,” Robert Ellsberg said. “So he said, ‘Let’s make this quick stop over there.’ He told my sister to wait in the car. She didn’t want to, understandably.” She followed them inside, where, Robert Ellsberg recalled, “he said, ‘Here Mary, here are scissors’ — playing with scissors was as exciting for her as Xeroxing was for me — and he said, ‘Cut off these words.'”

The words were “top secret.”

There were consequences to Robert Ellsberg’s actions — consequences which, for a 13-year-old, were probably more ominous than appearing before a grand jury, as he discovered when he announced to his mother, “Guess what we did today? I got to run a Xerox machine and copy documents with Dad.” (The grand jury came later, when the Nixon administration was pursuing espionage charges against his father.)

She “went through the roof,” Ellsberg said.

His mother, the daughter of a general, “confided to her stepmother, ‘I’m worried about what’s going on with Dan — Robert said he’s copying documents,'” Ellsberg said. “Unbeknownst to us, the stepmother goes directly to the FBI.” Soon agents came knocking — he remembers answering the door. He said they also spoke with his father’s boss at the RAND Corp., who “apparently told them that if he’s providing documents to Congress, he can do that.” (His mother died in 2013.)

Time passed — 1969 dragged on into 1970, then 1971. “I asked my father, ‘You know that thing we did, whatever happened with that?'” he said, deliberately avoiding being specific. “I had the feeling nothing was happening. He said, ‘Well, it’s frustrating.'”

One day in June 1971, “I heard on the news, ‘Today The New York Times has published documents from a top secret history of the Vietnam War,'” he said. “I knew immediately what it was. I jumped up and down.”

A few days later, the Supreme Court lifted an injunction against The Times (and The Post), ruling 6-3 that the Nixon administration had not shown why publication should be blocked for national security.

As a college freshman in 1974, Robert Ellsberg was faced with registering for the draft. He agonized, as many 18-year-olds did in those days, before telling the Selective Service System that he would not register.

Back came a letter from the Justice Department, saying he was being considered for prosecution. He decided that he was not prepared to risk going to prison, and registered. He also decided there were “deeper questions that I had to explore and that college wasn’t the place to do that,” so he withdrew from Harvard. He went to The Catholic Worker, where he became a disciple of the social activist Dorothy Day, who remains a hero to many Roman Catholics, 38 years after her death. He was arrested several times at anti-nuclear protests.

“I believe it was one of the ways my life was shaped by what happened when I was 13,” said Ellsberg, now editor and publisher of Orbis Books, a progressive religious publisher. “It put me in touch with a moral community that took it for granted that to be a human being is to try to follow what your conscience is telling you is right.”

He said he and his father are close now, and speak on the phone regularly. “I am much older than my father was when this all happened and I can say, ‘Yes, I am proud that I was able to play a little part in something that changed history,” he said.

He paused, then added, quietly: “Not just changed history but a legacy that continues to raise challenging questions in the present for other people about their responsibilities as citizens.”

This article originally appeared in The New York Times.