This drama has a final, largely invisible, chapter that involves Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, and Mark T. Esper, the defense secretary. They accompanied Trump on that walk across Lafayette Square, Milley in uniform. It was a decision they would both deeply regret.

Milley had been telling the president since late last week that it would be a mistake to invoke the Insurrection Act of 1807 and call out active-duty troops. Yet Trump told governors Monday that he was putting Milley “in charge” of a military response. The argument came to a head in the Oval Office that day, before the walk across Lafayette Square.

A burly man whose temper can match Trump’s, Milley was vocal in reiterating his advice to the president against mobilizing troops, according to three knowledgeable sources who spoke on condition of anonymity. Mullen and Mattis knew that Milley had taken this precarious position when they spoke out publicly, in part to support his effort to resist calling up the military. Trump hasn’t yet invoked the Insurrection Act, perhaps because he has weighed the private caution from his chief military adviser.