(CNN) -- It was sunny on Saturday in Washington, which was good news for Daniel Ellsberg. The most famous whistle-blower in American history was hoping to get arrested in the name of Bradley Manning.

"Oh, it's easy. I've done it before," he explained to CNN.com last week. "You don't have to do much to get arrested at the White House."

The spry 79-year-old got what he wanted. Twice. Ellsberg was arrested along with several others in front of the White House Saturday and then on Sunday outside Quantico military prison whileprotesting in support of the accused WikiLeaks leaker. Watch the protest and arrests

The cuffs made Ellsberg feel a little better. He's been angry for awhile -- disgusted is the word he often uses -- about Manning. The 23-year-old Army private has been locked up for nearly eight months at the Quantico brig.

Charged with 34 counts, including "aiding the enemy," the soldier faces life in prison and maybe execution, accused of illegally downloading hundreds of thousands of secret military and State Department documents and giving them to WikiLeaks.

To many Americans, Manning is a traitor. To many Americans, Manning is a hero.

To Ellsberg, he's something else.

"I was that young man; I was Bradley Manning," he says.

In the 1960s, Ellsberg was a high-level Pentagon official. He was a former Marine commander who believed the American government was the good guy. But while working for the administration of Lyndon Johnson, Ellsberg got access to a top-secret document that revealed senior American leaders, including several presidents, knew that the Vietnam War was an unwinnable, tragic quagmire.

The Pentagon Papers, as they became known, also showed that the government had lied to Congress and the public about the progress of the war. Ellsberg leaked all 7,000 pages to The New York Times, which published them in 1971.

Not long after, he surrendered to authorities and confessed to being the leaker. Ellsberg was charged as a spy, and he went to trial facing 115 years.

"I was willing to go to prison," Ellsberg says. "I never thought, for the rest of my life, I would ever hear anyone willing to do that, to risk their life, so that horrible, awful secrets could be known. Then I read those logs and learned Bradley was willing to go to prison. I can't tell you how much that affected me."

Ellsberg has been trying to see Manning but has had no luck getting on his visitors list. Ellsberg said he'd only pull Saturday's White House stunt if he knew he'd get out of jail in time to make it to Quantico on Sunday. A rally is being planned outside the prison.

By early last week four hundred demonstrators RSVP'd online, and the Bradley Manning Support Network, a conglomeration of nonprofit groups with members around the world, had paid for two chartered buses to take protesters to the enormous Quantico compound. Their plan, according to the group, was for everyone to hold signs bearing a photo of Manning's face -- a boyish mug, perhaps taken from the soldier's Facebook page -- and slowly march toward the prison gates. Watch Ellsberg at the protest

Turn-out was at least 400-strong. About 30 demonstrators were arrested, and Ellsberg wasn't the only high profile agitator. Col. Ann Wright, famous for quitting her top Pentagon post in 2003 to protest the U.S. invasion of Iraq, was also led away by authorities. As the crowd shouted "Free Bradley Manning!" several placed flowers at the foot of the Iwo Jima Memorial in front of the prison gates.

An open letter addressed to President Obama and Defense Secretary Robert Gates circulated amongst the demonstrators. It complained that Manning's case was being grossly mishandled.

Several signatures stood out: musicians Rosanne Cash and Michael Stipe of R.E.M.; artist Shepard Fairey; actors Danny Glover and Viggo Mortensen.

Ellsberg didn't expect crowd members younger than 55 to recognize his name. He was shocked that Manning knew it.

"As young as he is, he (knew) who I was," says Ellsberg, who contacted Manning's aunt, a D.C. lawyer who the soldier lived with briefly before enlisting in 2007. "I've let his aunt know of my support, my admiration."

Though he was as famous as anti-war singer Joan Baez in the 1970s, Ellsberg has lived a relatively quiet life since the Pentagon Papers. He's a respected author and lecturer and attended rallies against the Iraq and Afghanistan wars.

He meant it when he said he looked forward to getting arrested in front of the White House. How many times has he been arrested for protesting? "Oh, about 80," he replied.

Ellsberg isn't sure why he hasn't been able to see Manning. The soldier has received visitors: his lawyer, his aunt, a good friend from Boston and a PR person handling press for supporters donating money to his defense.

"I'd love for him to read my book," Ellsberg says, referring to his memoir, "Secrets," a colorful and personal account of the Pentagon Papers and Vietnam. "It's about an evolution, mine and maybe like his, of going from being a cold warrior, to someone who obeyed my oath, as I would say he did, by supporting the Constitution."

Ellsberg recites from memory the criminal code under which he and Manning were charged:

"18 U.S.C. 793... I'd tell him something about that because I know it," he says.

What else would he tell him or ask?

Ellsberg has been thinking about it.

"I'd like to know what else is in those chat logs," he says.

"Well, he probably wouldn't be in a position to tell me. And maybe I shouldn't ask."

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"i wouldn't mind going to prison for the rest of my life, or being executed ..." -- instant message believed to be written by Bradley Manning

Last summer, Ellsberg enjoyed national attention again -- this time for a documentary about his life. "The Most Dangerous Man in America," nominated for an Academy Award, took its title from the words former Secretary of State Henry Kissinger used to describe Ellsberg in 1971.

While critics across the globe gushed about the documentary, Ellsberg's focus was on another story: Bradley Manning had been taken into military custody, suspected of leaking a classified video. The clip, which WikiLeaks titled "Collateral Murder," showed an Army Apache gunship helicopter firing on unarmed civilians in Iraq, killing more than a dozen people, including two Reuters reporters. "Oh yeah, look at those dead bastards," one crewman can be heard saying.

Ellsberg watched the video, stunned. "Should the American public not see that?" he said. "I think they should."

At the end of July, The New York Times, two other newspapers and the WikiLeaks site published the Afghan War Diary, an on-the-ground account of the war effort. Those documents painted a much grimmer portrait than the one coming out of Washington.

Manning, who'd been detained in connection with the leaked video, soon became the suspect in the second leak.

"hypothetical question: if you had free reign over classified networks for long periods of time... say, 8-9 months... and you saw incredible things, awful things... things that belonged in the public domain, and not on some server stored in a dark room in Washington DC... what would you do?"

A California hacker named Adrian Lamo said he received that instant message, among others, from "bradass87," who he identified as Manning though Manning himself has never confirmed that.

Lamo contacted the FBI and turned over the logs he said captured Manning confessing to giving WikiLeaks a trove of intelligence the soldier allegedly downloaded from his post outside Baghdad.

The messenger told Lamo he had downloaded the documents from a "database of half a million events during the iraq war . . . from 2004 to 2009 . . . with reports, date time groups, lat-lon locations, casualty figures," and diplomatic cables "explaining how the first world exploits the third, in detail, from an internal perspective."

Lamo maintains that Manning initiated the conversation, seeking Lamo out because of his hacking reputation. As a teenager, Lamo broke into the computer networks of Yahoo, Microsoft and The New York Times (he reportedly inserted his name onto a list of the paper's esteemed contributors). Lamo surrendered to the FBI on September 11, 2003, and pleaded guilty to one count of computer crimes in early 2004. He got six months detention at his parents' home, two years probation, a $65,000 fine and a hard lesson, he told CNN.com.

"There are better things to be doing with my skills," Lamo told CNN.com.

Lamo worked hard to re-establish his reputation as a benevolent white-hat hacker. He was a changed guy. As such, he kept in touch with the FBI, he explained, just in case they might ever need his help.

That contact came in handy when the messages from "bradass87" popped up on Lamo's screen.

"I can't believe what I'm confessing to you ..." the messenger wrote.

Ellsberg, who has gone over and over the instant messages, is struck by one particular phrase.

Says the messenger alleged to be Manning: "its important that it gets out... i feel, for some bizarre reason ... it might actually change something ... ...I just... dont wish to be a part of it... at least not now... im not ready... i wouldn't mind going to prison for the rest of my life, or being executed so much ...

Lamo: What's your endgame plan, then?

The messenger: "hopefully worldwide discussion, debates, and reforms ...if not... that we're doomed ... as a species."

Ellsberg repeats the last line.

"It seems grandiose to say he will despair of the species ... the species," Ellsberg says, pausing a beat between the words as if he is weighing them again. "But I identify with that point of view.

"I don't talk about it very much, but I know exactly what he means." The wording, Ellsberg says, is "exactly appropriate."

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"Wouldn't you go to prison to help end this war?" -- Daniel Ellsberg to a reporter, 1971

Ellsberg's entire life has been dedicated to one cause.

It is the topic he studied at Harvard, the reason he got his doctorate in economics there. It was his focus during study at Cambridge University. It informed decisions he made as a Marine commander. It was his expertise at the policy-influencing think tank RAND, where he worked as a strategic analyst.

The cause: preventing nuclear holocaust.

Ellsberg's RAND research caught the attention of a former Harvard law professor who worked directly under Robert McNamara, Johnson's secretary of Defense. Assistant Secretary of Defense John McNaughton asked Ellsberg if he would come to work for him. The two had a trusting relationship, Ellsberg says, and McNaughton needed someone to ply through the stacks of documents McNaughton didn't have the time to read.

Ellsberg was trusted to go through top-level military communications from Vietnam and other sensitive documents and decide what to give to his boss, who would advise McNamara who in turn would advise the president.

His first week, Ellsberg faced a stack of papers nearly 12 feet tall, so he began asking to see only "hot stuff," or top-secret documents. That cut his workload down to two stacks a day, each 2 feet tall.

When Ellsberg read the first batch of WikiLeaks' documents about the Afghanistan War, which were largely field reports that were extremely low level but still technically secret intelligence, he was shocked.

"I was surprised about what there was to learn because I didn't even have time to look at that stuff," he said.

He became engrossed in the Afghanistan documents, and the ones released later on the Iraq War. But it was the publication of a trove of diplomatic cables in December that startled him.

The cables revealed that since 2007, the U.S. has tried to remove highly enriched uranium from a Pakistani research reactor that American officials are afraid could be used to make a nuclear weapon.

The cables also showed that the fear that a "rogue state" or a terror group from central Africa to central Asia would be capable of this was a constant preoccupation of U.S. officials. Another 2007 cable discusses the discovery of uranium in "multiple containers" in the Democratic Republic of Congo.

Ellsberg keeps thinking about Manning's message "... we're doomed ... as a species."

"We've got a species problem here when it comes to war," Ellsberg said. "The possibility for (nuclear) war, and it's implicated in stuff he's (Manning) revealing about Pakistan ... that we have a clear likelihood of destabilizing the government in Pakistan and putting nuclear weapons in the hands of allies of al Qaeda."

"This is a species problem. We're on a path toward nuclear war. We've been on it for 60 years."

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"its impossible for any one human to read all quarter-million... and not feel overwhelmed... and possibly desensitized ...the scope is so broad... and yet the depth so rich" -- instant message allegedly written by Bradley Manning

Ellsberg began to seriously question Vietnam after he saw it up close, working for two years in the late 1960s at the U.S. embassy in Saigon, the capital of South Vietnam. When he came back to the U.S., he was asked to contribute to a top-secret study. By 1969, it was complete.

Thirty-six analysts -- half of them active-duty military officers -- had contributed to the damning 7,000 page document.

"I can understand Bradley when he's going through all the documents -- which are just overwhelming in number -- how he feels he cannot grasp it," said Ellsberg.

Around that time, Ellsberg went to an anti-war rally at a Pennsylvania college. He listened to a young man who'd been imprisoned move the crowd to sobs when he told them that he welcomed going to prison rather than serve in Vietnam.

Ellsberg went to the men's bathroom, fell to the floor and cried. He knew what he had to do.

It doesn't matter, Ellsberg says, whether a leak exposes corruption, staves off suffering, helps end an unjust war or educates the public on how officials are acting, in secret, under their name.

What matters, in part, is how the country feels about the leaker.

Most of America opposed the Vietnam War by the time Ellsberg's trial commenced in January 1973. He ultimately avoided prison partly because of President Richard Nixon's "tricks."

In April 1973, the court learned that Nixon had ordered his so-called "Plumbers Unit" to break into the office of Ellsberg's psychiatrist to steal documents they hoped might make the whistle-blower appear crazy. In May, more evidence of government illegal wiretapping was revealed. The charges against Ellsberg were dropped.

He walked free.

His only sorrow was the friends he had lost.

"All of my old friends had clearances," he said. "They couldn't afford to have any association with me and didn't for decades. Total blackout, as if I had emigrated to another planet."

But he had new friends. "Twenty-five thousand people contributed to my trial," Ellsberg said.

Manning seems so much more alone.

Through Manning's aunt, Ellsberg has learned that the solider is estranged from his father, a military veteran. That's primarily because Manning is gay, according to friends and his own online writings.

Manning's mother, who lives in England, had a stroke, hampering their ability to communicate. The only friend Ellsberg is aware that Manning has is David House, an internet technology expert from Boston who has visited Manning at Quantico. At one point in the online chats with Lamo, Manning allegedly wrote, "I feel so isolated."

There are more differences between Ellsberg and Manning.

Ellsberg was charged as a civilian and before his trial began, he remained free on bond. He told his lawyers up front that he would speak for himself. With his wiry black hair and fast-charging comments, he became instantly recognizable. He laughs remembering that the FBI was looking for him while was on television one evening, giving an interview to Walter Cronkite.

Manning is facing court-martial and has been in custody since April, frequently in solitary confinement at Quantico, his lawyer has said. Manning has not been allowed to speak to any reporters. Last week, in statements on his lawyer's blog, Manning described his treatment at Quantico.

"I was stripped of all clothing with the exception of my underwear. My prescription eyeglasses were taken away from me, and I was forced to sit in essential blindness."

"I became upset. Out of frustration, I clenched my hair with my fingers and yelled: 'Why are you doing this to me? Why am I being punished? I have done nothing wrong.'

"The guard told me to stand at parade rest, with my hands behind my back and my legs spaced shoulder-width apart. I stood at parade rest for about three minutes ... The [brig supervisor] and the other guards walked past my cell. He looked at me, paused for a moment, then continued to the next cell. I was incredibly embarrassed at having all these people stare at me naked."

After this was released, State Department spokesman P.J. Crowley told a small group at MIT that Manning's treatment is "ridiculous and counterproductive and stupid." Crowley resigned days later.

Ellsberg is furious about that, and he blasted Obama for telling reporters that he had accepted assurance from the State Department that Manning is being treated humanely.

Responsibility for Manning's treatment "is very clearly on his shoulders," Ellsberg told CNN.com "and not some subordinates' shoulders."

And Ellsberg dismisses critics of Manning who say the soldier risked the lives of Americans or U.S. informants because WikiLeaks' didn't redact some names in its Afghanistan war documents.

The State Department said it has relocated people in other countries who may be in danger, but the government has made no evidence public that anyone has been harmed, Ellsberg reminds. "If they had one headless person," he said. "that headless person would be on the cover of Time."

Ellsberg likened Manning's treatment to torture, a way to make the soldier to confess or to divulge his relationship with WikiLeaks founder Julian Assange. "My guess is that it won't work," he said. "His (Manning's) courage is such that I don't think he will say anything false."

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"What more justification to leak?"

A few days ago, Ellsberg was at a party of the Harvard class of 1952. He listened as an alum, a psychoanalyst, told him:

"In my line of work, I understand Manning very well. He's just trying to get back at his father."

Ellsberg listened as the man went on: The Defense Department, he said, was daddy.

Jesus, Ellsberg thought. Ridiculous.

"I've run into real friends whose attitude" toward Manning and documents released by WikiLeaks "is totally shallow, uninformed, reflexive and uninterested," Ellsberg says.

He ticks off the revelations in the WikiLeaks documents:

• There were 15,000 more civilian casualties in the Iraq war than previously known.

• While the U.S. has given money to Pakistan and publicly called it an ally, Pakistani intelligence has allegedly helped Islamic extremists, including members linked to al Qaeda.

• The documents show widespread corruption in the Afghanistan government was hurting the U.S. mission there, and the classified materials revealed details about covert so-called death squads working for the U.S. and Britain.

• The most significant result of the leaks, Ellsberg insists, were diplomatic cables that spurred the uprisings in Tunisia, toppling a corrupt government and paving the way for a successful governmental overthrow in Egypt and protests to oust corrupt leaders in North Africa and the Middle East.

"Yet Bradley Manning should pay dearly," Ellsberg says. "He compromised national security. He's a traitor.

"What the hell?

"What the hell, you know? There's never been truth-telling that I know of that had that kind of immediate effect -- certainly not the Pentagon Papers."

The Pentagon Papers were published in 1971. The Vietnam War ended in 1975.

What more justification, Ellsberg asks, does Bradley Manning need to leak such secrets?