Daniel Ellsberg, the Pentagon Papers whistleblower.
For those who haven't watched it, the Ken Burns 2017 Vietnam War documentary series is well worth your time and may be available to view on the PBS website (may not work in Canada), and while it only deals peripherally with the Ellsberg case during the final episode, it incorporates essential information from his Pentagon Papers release throughout the series.
I've told this story before on previous forums. My dad was a Vietnam veteran. An older boomer from rural Kentucky, a high school graduate (without the best grades) who was spending 1967 taking nursing classes at community college, he was a prime candidate for getting picked in the draft "lottery", which in actuality overwhelmingly picked working-class non-academic men. But my dad wasn't that dumb, and had the bright idea to pre-emptively join the Navy, which had a relatively milder boot camp and training regimen, and floating in the Gulf of Tonkin seemed like a vastly superior option to squatting in the Bush with Charlie. Shortly after his first mandatory sea deployment (circa 1969), my dad's superior officers noticed his interest in nursing classes, and offered him an opportunity to become a Navy medic, or a corpsman (interesting pun, eh?). My dad thought, "Great! I'd rather work to save lives than take them." But what my dad didn't quite understand yet was that the Marine Corps. uses Navy corpsmen to serve with their platoons, and so my dad instead soon found himself embedded along the frontlines of Khe Sanh. As a corpsman, my dad was an intimate witness to the senseless corporeal costs of the war. And my dad would also soon learn that it was the VietCong strategy to aim first for the corpsmen so that any future casualties will go unaided. But luckily, he managed his tour without earning a purple heart.
My dad didn't care much for Daniel Ellsberg. It's not that he found him to be a traitor or anything, rather, like a number of veterans, he was never entirely willing to process the anger that resulted in his war experience, and Ellsberg was simply a messenger of the worst news, the scarring insult that all of that blood and sacrifice was not only useless and unnecessary but that those at the top knew it and sent these young men to their deaths anyway. (Classic Paths of Glory pathos.) My dad also never expended much fondness on Henry Kissinger or Robert McNamara either.
In 2017, when I watched the Burns Vietnam doc, I was eager to recommend it, but my dad wanted nothing to do with it. "I was there". I was aware, but I felt that there's a trough of facts and details and historical context that, given the deception exposed by Ellsberg, are exactly the kinds of things for those who were there were deprived of and could be useful to understand in hindsight. But I didn't push the matter. In many ways it's also unnecessary to do so. Ellsberg's service is for those of us who weren't there, and for the children of its history. My dad was not in denial about the farce of the cause. That's knowledge that those who were there know all too well. My dad felt like he'd earned the right to not be reminded of this fact by those who weren't.