McMaster is not only familiar with this history, he’s obviously digested its lessons. While the joint chiefs were “derelict” in their duty by keeping silent about their views on Vietnam, it’s not clear their dissent would have made a wit of difference. Indeed, while the nation’s military leaders have a duty to tell the president what they think, there’s no requirement that the president actually listen—let alone follow their advice. And Wheeler, despite his myriad critics, had it right: 24 hours after walking off the job, there would be “new guys” sitting in their chairs who would try to make the best of a bad situation, which is precisely what Wheeler and his colleagues were trying to do.

That’s what H.R. McMaster is doing now—though unlike his predecessors during Vietnam, he has considerable latitude to do so. The grapevine thinking among senior military officers when McMaster was named national security adviser was that Trump needed him more than he needed Trump. That certainly wasn’t true for L.B.J. and Earle Wheeler. Johnson was an imposing presence, while Wheeler was a virtual unknown whom Johnson could have kicked easily to the curb. President Trump will have to think twice before doing that to his national security adviser.

McMaster (along with James Mattis and, to a lesser extent retired General John Kelly) lends a patina of badly needed varnish to the administration’s unfinished exterior. Additionally, reporter Eli Lake’s vivid recounting of how Trump screamed at McMaster during a telephone exchange isn’t bad news. Rather it shows that the national security adviser is doing what Earle Wheeler and crew failed to do some 50 years ago: He’s telling the president what he doesn’t want to know and, probably in tones that Trump rarely hears. (McMaster’s initials, those who know him best say, stand for “heat round”). Finally, while it’s possible that McMaster’s reputation will suffer by being associated with a failing administration, history has a way of vindicating those who do their duty, while relegating to historical footnotes those who simply go along.