Read: James Mattis’s letter of resignation

Mattis was also the man who said, “Engage your brain before you engage your weapon,” the commander who praised the quick-thinking Marine squad leader who was smart enough to take a knee when he saw a Shia funeral procession filled with armed men walk by in the newly liberated streets of Nasiriyah, in southern Iraq. And above all, he was the division commander who, when his tour was over, got in a car and crossed the country visiting families of his fallen Marines. To see him explaining to his security detail and his driver the political importance of driving into downtown Ramadi to hobnob with the potentially hostile sheikhs was to see leadership of a subtle kind. Those young Marines were ready to follow him anywhere. Literally, anywhere.

The president had a vague notion of the killer part when he appointed Mattis. He had no notion of the morally and strategically informed restraint, of the intellectual sophistication, of the selflessness.

It was not Mattis’s idea to become secretary of defense, and indeed, he may not have been the best pick for the job in normal times. But then again, 2017 was anything but a normal time, and even those who believed that the job should in principle go to a real civilian rather than a retired general were relieved that Mattis took it. In office, he had to spend most of his time buttressing the alliances that the president despised, and affirming values of fairness and legality that Trump could not comprehend. Success in government is often measured less by the brilliant things one does than by the stupidities one prevents. By that standard, Mattis’s tenure as secretary of defense was a success.

Read: The Trump administration’s lowest point yet

His story, however, has a larger significance. From the unlikely victory of Trump in the November 2016 election to the present, some have argued that principled patriots could serve in high office, retain their character, and either mitigate the damage or do some positive good. To be sure, they would need their red lines, their signed-but-undated letters of resignation. But they could pull it off. Though they might be maligned by irresponsible enemies of the administration, they would serve the country, and do so more honorably than mere critics.

Mattis indeed had his walking points, and he leaves with his head held high. But he is alone. The clusters of sub-Cabinet officials who privately boasted about their walking points have, with very few exceptions, stuck it out. They give sickly smiles when, at a seminar or dinner party, someone describes the president’s character as it is; they give no evidence of sticking their necks out to take positions that might incur the wrath of the America Firsters; they have taken the mad king’s shilling, and they are sticking with the king.