This piece was originally published in The Atlantic.

The two most controversial defense secretaries of modern times were Robert S. McNamara and Donald Rumsfeld. Both presided over wars in which American self-deceptions about the countries being invaded shaped strategies that ran afoul of realities in the battle arenas. The outcomes were outright loss in Vietnam and, at best, ambiguous resolutions in Iraq and Afghanistan. In their ninth decades, both men agreed to undergo the scrutiny of the brilliant documentary filmmaker Errol Morris, whose portraits showed how these two once-powerful and influential men confronted their past with a spectrum of response: humility and regret in McNamara’s case, and chilling smugness in Rumsfeld’s.

Sometime around the turn of the century, Robert McNamara called me—I had been the publisher of his memoir, In Retrospect: The Tragedy and Lessons of Vietnam, and his two subsequent books—to say that a man named Errol Morris, who he had never heard of, wanted to interview him on camera for a possible film.

“What is your capacity for further public ignominy and evisceration?” I asked. I expected Morris to reinforce the image of McNamara as an insufficiently penitent architect of the Vietnam War. McNamara’s mea culpa in his memoir was widely criticized as way too little and way too late—a failed bid for redemption.

But in his 80s, and eager to see his warnings about the perils of making war reach a wider audience than even his bestselling book, McNamara agreed to sit for hours of questioning by Morris. The film that emerged from the collaboration—The Fog of War—won the 2003 Academy Award for Best Documentary Feature. In my (admittedly biased) judgment, at least, the film succeeded in giving McNamara the opportunity to examine the calamity that Vietnam represented and explore how similar tragedies might be avoided. The movie continued McNamara’s efforts to revisit the decisions that led to the conflict, with this goal as expressed in the opening pages of In Retrospect:

We of the Kennedy and Johnson administrations who participated in the decisions on Vietnam acted according to what we thought were the principles and traditions of this nation. We made our decisions in light of those values. Yet we were wrong, terribly wrong. We owe it to future generations to explain why.

McNamara’s determination to leave a legacy that might somehow prevent a repeat of history—an American engagement in a war that would fail to achieve honorable objectives and a democratic denouement—will no doubt be in the back of many viewer’s minds as Morris’s newest film, The Unknown Known, rolls out in theaters (and, simultaneously, on-demand from cable outlets and iTunes). In his new movie on Rumsfeld, Morris’s approach is very much the same as it was with McNamara. His off-camera voice poses questions and, amid archival clips and original musical soundtracks, the subjects reveal personalities that are riveting in their differences.

The film on McNamara drew heavily from his experiences—reaching as far back as his time in service during World War II and the Cold War, especially the Cuban missile crisis, and exploring his outlook shaped by the long-term dangers of confronting the Soviet Union—to frame the lessons that he learned for avoiding future war. McNamara’s sense of responsibility was palpable in the film (as it was in his books), though he chose his words carefully, refusing to say why he did not speak out against the Vietnam War and declining to assess his successor’s policies. “You don’t know what I know about how inflammatory my words can appear,” he said, in a climactic exchange. “A lot of people misunderstand the war, misunderstand me. A lot of people think I’m a son of a bitch.”

By contrast, the thrust of Rumsfeld’s jousts with Morris are built around his stream of memos—he estimates there were 20,000 in his years at the Pentagon—and linguistic formulations, the most famous of February 4, 2002, in which he wrote, “There are knowns, known unknowns, and unknown unknowns. … There are also unknown knowns: things you think you know that it turns out you did not.” Whereas McNamara is a man grappling with the consequences of his actions, Rumsfeld, as characterized by Morris, “is a man using language to obscure the world from himself as well as from others.”

The Robert McNamara I came to know in the decade we worked together sought to provide an analytical framework to the wars he fought and his determination to minimize other conflicts in a nuclear age. And yet, in his books and in The Fog of War, a personal anguish about the past and deep concern over the future comes through very clearly. The Donald Rumsfeld of The Unknown Known is a man whose conclusion about his responsibilities sidesteps any self-doubt or criticism, leaving the impression that if there is blame for what happened in Iraq, it does not belong to him. His approach to all matters, he insists, is “cool, measured.” For all we know, Rumsfeld really has so few second thoughts and insights, almost reveling in his maneuvering with Morris to limit his assessment of Iraq’s costs. In response to the question of whether the war was worth the consequences, Rumsfeld replied, “Only time will tell.”

The Fog of War‘s power came from how skillfully Morris crafted a narrative that showed a man in his twilight grappling with himself over what he had wrought. In The Unknown Known, we see Rumsfeld doing what he can to avoid dealing with Morris’s probing, but ultimately he falls short. His self-regard is offensive. That was certainly Morris’s conclusion as well. As he told Fred Kaplan in a New York Times interview, “Any account of him has to deal with the gobbledygook, the lies, the glibness, the cleverness—but also his emptiness.”