Donald Trump’s claim that he will be arrested imminently has sparked political maneuvering and a debate about the implications of indicting an ex-president.

No president or former president has ever been indicted. But a sitting president was arrested once.

In 1872, President Ulysses S. Grant was arrested at the corner of 13th and M streets NW in Washington. This was not a high crime, but it was — at least theoretically speaking — a misdemeanor.

The man who led the North to victory in the Civil War was busted for speeding in his horse-drawn carriage.

The story of his arrest — confirmed in 2012 by Cathy L. Lanier, who was then D.C.’s police chief — was told in a remarkable but obviously forgotten story in the Sept. 27, 1908, edition of the Washington Evening Star under the headline: “Only Policeman Who Ever Arrested a President.”

That policeman was William H. West, a Black man who had fought in the Civil War.

“Since his retirement,” the story said, “he has decided to let the public know the true story of the arrest.”

It begins with Grant’s love of fast horses.

“Gen. Grant was an ardent admirer of a good horse and loved nothing better than to sit behind a pair of spirited animals,” the Star reported. “He was a good driver, and sometimes ‘let them out’ to try their mettle.”

And that’s where Grant, as president, rode into the law.

The police had been receiving complaints of speeding carriages. After a mother and child were run over and badly injured, Officer West was dispatched to investigate. As West spoke to witnesses, another group of speeding carriages headed toward him — including one driven by the president of the United States.

“Policeman West held up his hand for them to stop,” the story said. “Grant was driving a pair of fast steppers and he had some difficulty in halting them, but this he managed to do.”

Grant was a bit testy.

“Well, officer,” he said, “what do you want with me?”

West replied: “I want to inform you, Mr. President, that you are violating the law by speeding along this street. Your fast driving, sir, has set the example for a lot of other gentlemen.”

The president apologized, promised it wouldn’t happen again and galloped away.

But Grant could not curb his need for speed.

The next evening, West was patrolling at the corner of 13th and M streets when the president came barreling through again, this time speeding so fast that it took him an entire block to stop.

Now Grant was cocky and had a “smile on his face,” the Star reported, that made him look like “a schoolboy who had been caught in a guilty act by a teacher.”

He said, “Do you think, officer, that I was violating the speed laws?”

“I do, Mr. President,” West said.

Grant had an excuse for his speeding, not unlike one no doubt being given somewhere right now: He had no idea he had been going so fast.

West was sympathetic but firm.

“I am very sorry, Mr. President, to have to do it,” he said, “for you are the chief of the nation, and I am nothing but a policeman, but duty is duty, sir, and I will have to place you under arrest.”

It’s worth pointing out here that standards of journalism, particularly with quotations, were not as rigorous back then as today, so it’s nearly impossible to know whether this is the whole truth and nothing but the truth.

However, Lanier did confirm the arrest, and there are other historical references to it.

Anyway, Grant and several of his speeding buddies also arrested went with West to the police station. The president of the United States was ordered to put up 20 bucks as collateral. A trial was held the next day.

“Thirty-two ladies of the most refined character and surroundings voluntarily came into the court and testified against the drivers,” the Star story said. “The cases were contested bitterly.”

The judge imposed “heavy fines” and a “scathing rebuke” to the speeding drivers, who didn’t include the president.

He didn’t show up for court.

A version of this report was originally published in The Washington Post on Dec. 16, 2018, under the headline “The police officer who arrested a president.”