The hobgoblin of history — or what the New York Times is mocking as “the alternative past” — is catching up with President Trump. It sprang when the 45th president suggested that Andrew Jackson had been “really angry” about the Civil War, which, the Times claims, failed to break out until sixteen years after Jackson’s death. That claim is accurate only if one dates the Civil War from Fort Sumter, rather than from, say, the Force Bill that, in 1833, authorized the raising of an army to put paid to nullification in South Carolina.

Talk about your alterative past. That Nullification Crisis was a humdinger. It was ginned up by John C. Calhoun, who actually quit as vice president to oppose the tariffs the federal government was trying to impose at the expense of the South. He won a compromise bill in which the Congress eased up. Calhoun’s own reputation, though, was forever tarnished by his defense of slavery. Yale University apparently found out about this only recently and promptly removed Calhoun’s name from one of its dormitories. How was it supposed to know?

President Jackson himself is one of the most elusive figures in the whole alternative past. Abraham Lincoln had nothing on Old Hickory, even if one Hollywood blockbuster about the alternative past portrays Lincoln as a vampire hunter. Even more amazing, Lincoln turns out to have been a Republican, which is why the Republican Party names so many of its fund-raising dinners for Lincoln. Now, though, we have, in Mr. Trump, a Republican president who, right off the beam, hangs Andrew Jackson’s portrait inside of the actual Oval Office.

Jackson founded the Democratic Party, for crying out loud. Whether Mr. Trump was aware of this when he hung Jackson in the Oval Office (and right beside the Resolute Desk, which was transparticulated into the Oval Office by yet another Democrat, John F. Kennedy, who launched the Vietnam War the Democrats abandoned). Then again, too, when modern-day Democrats discovered how badly Jackson treated the Indians, they started dropping his name from their fund-raising dinners and are in the midst of throwing over another rascal, Thos. Jefferson.

It’s not our purpose here to belittle this obsession with history or to make light of anyone’s ignorance (the future editor of the Sun once lost two dollars in a bet that there had never been an American president named Taft; the two-spot was pocketed by Walter Mossberg of the Wall Street Journal). We actually favor our politicians being up on their history and the attachment to it of importance, including all the symbolic features of our national drama. Yet one of our favorite themes, oft-mentioned in these columns, is the tricks history can play.

Here is, in Mr. Trump, an American president being mocked for his particulars in respect of Andrew Jackson by the party that was the home of the Dixiecrats until the Republicans got the Civil Rights Act passed. Only a few years after the New Republic ran its notorious cover story suggesting that the GOP had become the party of Calhoun, the Democrats fetched up in the 9th United States Circuit asserting the power of the states to nullify the federal statute authorizing the president to suspend immigration and to defy federal law via sanctuary cities.

So all this poses for the Democrats a devilish dilemma. Do they want to mock Mr. Trump for failing to credit their interpretation that the Civil War began 16 years after Andrew Jackson died? Or do they want to permit him some modesty that comes with the cloak of the alternative past? Our own instinct is for the Democrats to be charitable toward Mr. Trump. Otherwise he is liable to turn on them the next time they carry on about the evils of Old Hickory and demand of the Democrats who stuck with him so long, “What did you know and when did you know it?”