Under ordinary circumstances, open dissent from high-ranking military officials against the actions of civilian political leaders would signal a danger familiar to other countries. Such rumblings from military circles often indicate that constitutional freedoms are in jeopardy and that martial law, or even a coup d'etat, may be on the horizon.

In these extraordinary circumstances, however, all expectations are reversed — and the usual order of things is turned upside down.

So, rather than sounding ominous, the blunt rebukes of President Donald Trump by retired and active officers this week sounded reassuring. They said our most respected military leaders will not stand by silently while this president and his crowd deface the Constitution and menace the nation.

The first to speak out was James Mattis, a venerated retired Marine general who served as secretary of defense under Trump until their disagreements forced him to resign. Until now, Mattis had resisted the urge to criticize the administration as a matter of principle. But like many Americans, apparently including his fellow officers, Mattis felt horrified watching peaceful protesters driven from Lafayette Square by brute force so Trump could posture in front of a church, brandishing a Bible (which he held upside down).

Mattis acted swiftly, issuing an acerbic statement that he opened by describing himself as "angry and appalled." Published first in The Atlantic and then widely reprinted, it is very much worth reading in full. He condemned the actions of not only Trump but also his successor, Defense Secretary Mark Esper, and Gen. Mark Milley, the current chairman of the joint chiefs of staff. He wrote: "When I joined the military, some 50 years ago, I swore an oath to support and defend the Constitution. Never did I dream that troops taking that same oath would be ordered under any circumstance to violate the Constitutional rights of their fellow citizens — much less to provide a bizarre photo op for the elected commander-in-chief, with military leadership standing alongside."

Provoked by Trump's authoritarian misconduct, Mattis said at last what he has surely known for years, namely that Trump is unfit for public office and represents an existential threat to our values and society. He dismissed Trump as immature and worse, a political charlatan who incites division instead of unity in a style that Mattis likened to the Nazi ethos of "divide and conquer." He advised his fellow Americans, as we confront the nation's legacy of racism and establish true equality under law, to disregard the president.

"We can unite without him, drawing on the strengths inherent in our civil society," wrote Mattis. "We know that we are better than the abuse of executive authority that we witnessed in Lafayette Square. We must reject and hold accountable those in office who would make a mockery of our Constitution."

Within hours of Mattis breaking from Trump, other flag officers followed.

Retired Gen. Mike Mullen, former joint chiefs chairman, issued his own statement saying that the events in Lafayette Square "sickened" him and he could no longer remain silent. The president, wrote Mullen, "laid bare his disdain for the rights of peaceful protest in this country, gave succor to the leaders of other countries who take comfort in our domestic strife, and risked further politicizing the men and women of our armed forces." Another former joint chiefs chairman, retired Gen. Martin Dempsey, expressed deep dismay. So did retired Gen. Raymond Thomas, the former chief of Joint Special Operations Command, as well as retired Adm. James Stavridis and retired Gen. Wesley Clark, both former supreme allied commanders of NATO.

No doubt the phone lines into the Pentagon have been lit up with outrage in recent days, prompting Esper and Milley to distance themselves from Trump and his antics. The president himself, backing away while still snarling, dropped his threat to deploy military troops in cities. The troops are leaving Washington now.

Speaking out in defense of constitutional order, these retired officers articulated a fundamental principle: Unlawful orders to fire on fellow Americans are not to be obeyed. We live in a republic, not a dictatorship. And should Trump or his cohort harbor any militaristic fantasies about the upcoming election — which he appears likely to lose — well, this uplifting episode marked a line that they shouldn't dare cross.

To find out more about Joe Conason and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.