Daniel Ellsberg, who died on Friday at 92, will be remembered as one of the most consequential war resisters in American history. Had he not possessed an integrity vanishingly rare within the national security circles that produced him, Ellsberg’s life might have ended up like Henry Kissinger’s.

Ellsberg was a Cold Warrior in the 1960s. The term “the best and the brightest” has lost much of its caustic irony over the years, but David Halberstam applied it to young, self-confident defense wonks like Ellsberg, who were out to rationalize and harness American military power in a struggle for the fate of the 20th century. Far smarter than most of his peers, Ellsberg came to see that career paths like his own—Defense Department official, Rand Corporation analyst—encouraged delusions that put America, and the world, at risk. Too much exposure to classified intelligence, he once warned Kissinger, will make you “something like a moron. You’ll become incapable of learning from most people in the world,” who lack access to it.

Seeing Vietnam up close—not just the human carnage, but also how the foreign policy apparatus absorbed and perpetuated it—broke Ellsberg’s faith in the morality of his enterprise. But it wasn’t until Ellsberg, by then ensconced at Rand, visited Haverford College in August 1969 that his ultimate direction in life was set. That was when Ellsberg attended a conference of the War Resisters’ International, which he described in his 2002 memoir Secrets as a shattering, life-changing experience.

Ellsberg’s account of the conference presents candidly an allergy he had, one shared by many subsequent participants in US foreign policy and national security circles, to the people he attended it alongside. He described his “misgivings about the dogmatic commitment to absolute pacifism I presumed they shared.” Ellsberg no longer supported the Vietnam War, but he hesitated to join ranks with people whose critiques of American foreign policy were more fundamental than his. “My knowledge of such people still came almost entirely from media accounts, overwhelmingly negative, in which they were presented as being, in varying degree, extremist, simplistic, pro-Communist or pro-NLF [National Liberation Front, or the Viet Cong], fanatic, anti-American, dogmatic,” he writes.

But then, at a demonstration outside a trial for draft resister Bob Eaton, he began to feel something else: the “exhilaration” of solidarity. “I had become free of the fear of being absurd, of looking foolish, for stepping out of line,” he recounts.

The next day, Ellsberg attended a talk by the peace activist Randy Kehler. Kehler “talked about nonviolence as a way of life, about hope, about two worlds both existing just now, a waning world dominated by fear, an emerging world becoming more and more like a family.” By the time Kehler spoke casually about going to prison alongside his comrades, secure in the knowledge that others in the movement would continue the work until the war ended, Ellsberg was “breathing hard, dizzy, swaying,” until he began sobbing, a full-body catharsis that reads like a panic attack.

What followed was resolution. “I was capable of going to prison to help end” a war that previously he had served, Ellsberg wrote. Inspired by Kehler’s example, “I realized I had the power and the freedom to act the same way.” From that moment came the leak of the Pentagon Papers to New York Times reporter Neal Sheehan and everything that followed: an epochal press-freedom victory in the Supreme Court, Ellsberg’s trial and exoneration, the Watergate break-in by the White House “plumbers” who had hunted Ellsberg; Richard Nixon’s impeachment and resignation.

Perhaps the most remarkable aspect of Ellsberg’s memoir is how, decades later, he was able to summon and describe the institutional pressures that made him reluctant to join the protest for Eaton. His bosses in Washington or Santa Monica “would see it as a total sacrifice of dignity and of elite insider status, for nothing, for an action of no consequence, no effectiveness, nothing worth taking the smallest risk of losing access to secret information and to people of influence.” He likened publicly resisting the war to shedding skin, leaving him feeling “naked—and raw.” “My life was split in two,” he writes, cognizant that his friends and colleagues would denounce him.

It’s tempting to view Ellsberg’s life, now that he has passed away, as a glide path to the actions he took. But the power of his memoir lies in its recognition of how contingent his decisions were. Ellsberg easily could have let others sacrifice to end the war, convincing himself that he was more valuable as an internal wrench in the war machine. Enjoying continued respectability, bureaucratic power, and technocratic prestige, Ellsberg could have reconciled his opposition to Vietnam with the broader thrust of US foreign policy, making it his mission to temper the excesses of the Cold War. After the Cold War, he might have made his peace with American primacy, as did so many liberals of Ellsberg’s generation, and reaped the luxuries that go with graybeard status.

Ellsberg published his memoir during the War on Terror. When I read Secrets, more than a decade into that disaster, it struck me that there was no Ellsberg for the post-9/11 era. There were many whistleblowers of courage from inside the security state: Chelsea Manning, Edward Snowden, Daniel Hale. But their positions within were far lower than Ellsberg’s, who advised men like Kissinger and had eminent mentors like the Harvard economist Tom Schelling. The people of Ellsberg’s equivalent rank and early-career promise more typically chose to serve the War on Terror, not resist it, going along with atrocities abroad and democratic destabilization at home.

It was hard not to think of them, and of Ellsberg, when reporter Jonathan Guyer chronicled their pilgrimage earlier this month to Kissinger’s grand 100th birthday celebration. There was Secretary of State Tony Blinken, retired Gen. David Petraeus, USAID administrator Samantha Power, economist Larry Summers, billionaire New England Patriots owner Robert Kraft, former Google CEO Eric Schmidt. Nothing could more thoroughly validate Ellsberg’s experience at Haverford than the way all these respectable figures paid homage to the premiere American war criminal of the 20th century.

Ellsberg, 50 years ago, showed that another path was possible. It does not diminish his achievements that so few people who achieve his vantage within the vast national security apparatus, knowledgeable of the great devastation it wreaks as a matter of course, choose to take it.