May 17, 2017–Now the truth stands revealed. When then-Lieutenant Colonel McMaster published his book Dereliction of Duty in the middle 1990s he got an extremely friendly reception. He rode that to generals’ stars, command in Iraq, scuttlebutt finding him a suitable candidate for chief of staff of the United States Army, and more. Today, Lieutenant General McMaster is national security adviser to the President of the United States. On the White House podium yesterday it all came tumbling down.

There were some more doubtful observers of the McMaster parade, me among them. I always thought McMaster’s argument about the Vietnam war a cheap shot. I said so in historian circles and in my book Unwinnable War. The thesis in McMaster’s book was that the Joint Chiefs of Staff (JCS) and NSC staff at the time of the Vietnam war played the inexcusable roles of enablers by going along with President Lyndon Baines Johnson’s strategy–partial, cautious steps, fragmentary escalations–instead of demanding action on their real, much more forceful menu of operations. By McMaster’s lights this left the United States on an uncertain, wavering course, meandering through history to defeat in Vietnam. I thought McMaster wrong both in general and in detail. It was not true the JCS never held out for their “large solution” operations. What was true was rather that each time a major strategic review occurred the Chiefs argued for the large solution. Lyndon Johnson, acutely aware of the dangers war in Vietnam could morph into war with China or Russia or both, consistently resisted the maximum escalation. While LBJ staged scenes to denounce and embarrass the generals they never, in fact, gave up their underlying strategy. They were never guilty of dereliction of duty in the sense that H. R. McMaster (and the U.S. military) use the term.

The generals (and NSC staff) did act to preserve the dignity of the president and his office. They did not complain of the president’s high handedness. Only one, Army chief Harold K. Johnson in 1967, contemplated resigning in protest (hoping LBJ might agree to war mobilization and an invasion of North Vietnam to dissuade him). He didn’t do it–and he, too, kept his silence on what had happened.

McMaster’s prescription in his book was that an official, faced with such a dilemma, must resign in preference to dereliction of duty. Yesterday, in reality, the general met his Waterloo. Elevated to national security adviser, Hal McMaster serves Donald J. Trump. The president blocked his national security adviser from ousting staff who made trouble, prevented McMaster from keeping offensive rhetoric out of Trump’s public comments, and kept silent as the president called him a “pain.” In the past week the general no doubt watched in horror as President Trump fired the FBI director even as evidence of an attempt to manipulate a federal investigation began surfacing. Then, a few days ago, Mr. Trump blabbed to visiting Russian officials of secrets given the United States by an intelligence ally, reportedly Israel. This violation of every protocol regarding handling of classified information, Mr. Trump defended with the bland defense that, as president, he can declassify any intelligence.

General H. R. McMaster stood up for President Trump. He denounced the Washington Post’s report that Trump had leaked classified information, “It didn’t happen.” Why not? Not because it did not happen but because a president can decide to declassify secrets. Yesterday McMaster took the podium at the White House. He made more excuses for Trump. “The president wasn’t even aware,” the general said, “where this information came from.” The president had an “absolute right,” the general said. Nine times the general insisted that what President Trump had done was “wholly appropriate.”

Lieutenant General H. R. McMaster did not resign in protest. He did do precisely what his forebears had done during the Vietnam war–act to preserve the dignity of the office of the president. General McMaster seems to have discovered appropriate dereliction of duty.