The holiday week leading up to New Year’s has special meaning. The day after holy Christmas, we celebrate the wholly mercenary observance of Exchange Day.

It’s not an official holiday in the United States, but it should be, like Boxing Day is in British Commonwealth countries and other outposts of civilization. You remember the British Commonwealth, don’t you? That was the worldwide collection of countries under the influence of England, before the demise of the U.K. — a downward slide that is nearly identical to what the U.S. is undergoing now.

That was long before Brexit, where the demagogues successfully played on the latent hatreds of the Brits in order to commit financial suicide by trying to pull away from the rest of Europe. Again, it’s uncannily similar to Americexit, a term I just made up to describe how our current leadership is trying to lead us to oblivion by removing us from the rest of the planet.

As usual, I’ve digressed. This is about returning unwanted merchandise.

President Donald Trump is dumping a whole year’s worth. Actually, sometimes he’s the dumper, but often he’s the dumpee. No matter that Trump decided to terminate him early, Gen. Jim Mattis — who had gone on to be President Trump’s secretary of defense and was considered by nearly everyone to occupy the ever-shrinking corner of reason in the Trump solar system — got tired of his expert advice being trashed, and either the sudden decision to pull out of Syria or the pullout planned for Afghanistan was enough to push him over the edge. We know what motivated him because he made it clear in his resignation letter:

“Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position.”

The only way he could have been clearer is if he had told the president what he could do with himself.

By the way, Mattis is not the only one. Even many of Trump’s fellow Republicans are in an uproar over Trump’s impetuous moves. Still, POTUS will take great comfort in knowing that his autocrat role models Vladimir Putin and Recep Tayyip

Erdogan wholeheartedly approve.

Mattis, however, is bailing. He’ll soon be followed out the door by John Kelly, another retired Marine four-star whose brass was tarnished. Kelly has reached his limits as White House chief of staff, and while he didn’t enjoy the universal adulation that Mattis accumulated, the two of them will do their Semper Fi bye-bye at the same time, retreating from the battles they lost.

They’re trailing a three-star out the door. H.R. McMaster left in April 2018, after he ran afoul of the capricious emperor Trump. Let us not forget that he replaced another one, Michael Flynn. Gen. Flynn was sooooo last year, unless you count his indictment by Bob Mueller, who’s investigating alleged Trump campaign Russian collusion.

Flynn is currently singing like a songbird to avoid prison time.

This has not been a good year for generals, particularly if you include attorneys general, like Jeff Sessions.

By the way, did you know that the proper way to address an AG is “General”?

One can assume that he’ll retain the title even though he’s now a former one. Of course, he’s a former senator, too. What does etiquette dictate is the proper honorific?

Speaking of damaged goods, they have slimed his cabinet full of holes. Interior Secretary Ryan Zinke is the latest to slither out of industry’s pockets.

But he allegedly got greedy, just like Scott Pruitt at the Environmental Protection Agency.

Right now we are in the throes of still another partial government shutdown, widely blamed on Donald Trump’s rash untrustworthiness. This doesn’t figure to improve until he’s the one who’s being exchanged.

• By BOB FRANKEN