Predicting what history will decide was significant is always dicey. But in the context of our fractured nation and the nonstop Washington tumult since 2016, events in the last three weeks have been nothing short of ­remarkable.

Against an enormous army of antagonists, political and cultural, academic and judicial, Donald Trump is enjoying some of the best days of his presidency. His power and popularity are expanding.

Meanwhile, Democrats and the left, including the media, have suffered one crushing blow after another. Their recent confidence that Trump was not long for the Oval Office is suddenly morphing into a panic that he could win a second term.

The worm began turning on the ­afternoon of Sunday, March 24, when Attorney General William Barr released his letter summarizing the findings of special counsel Robert Mueller. There was no collusion with Russia, Mueller found, and no obstruction of justice, Barr determined.

The momentous victory for Trump vindicated his claims of innocence. The fog of accusations that he was an illegitimate president was destroyed by a news flash that left no room for ambiguity.

To grasp the significance, imagine the consequences if the report found he was probably guilty of one or both charges.

The left would have erupted in ­orgasmic joy. We would be discussing articles of impeachment and Republicans would have fallen in line. There would have been worldwide implications as America turned inward to face its crisis.

Yet it is now apparent that Mueller’s report, as great as it was for Trump, was just the start of a dramatic turnaround in the fortunes of both the president and his tormentors. The bookend, at least so far, came last week with Barr’s stunning comment that “spying did occur” on Trump’s 2016 campaign and that Barr was obligated to review “the conduct of the investigation.”

“Spying on a political campaign is a big deal,” Barr said matter-of-factly.

Heart be still. Barr’s promise touches on the holy grail for those of us who believe there was an outrageous abuse of government power to try to tip the election to Hillary Clinton and then to topple Trump.

If Barr keeps his word, the sunlight of transparency soon will shine on the rancid corruption of the Justice Department, the FBI and the intelligence agencies under Barack Obama.

Turning the tables on the conspirators is absolutely necessary to hold accountable those who tried to rig the election. That accountability, if it is seen as honest and evenhanded, will prevent a repeat and begin to restore public trust.

Among the obvious questions that must be addressed are these: How did the unprecedented FBI probe of a presidential candidate get started if the allegations were instigated and paid for by the opposition? Who leaked scores of misleading investigative tidbits to the media in ways that suggested Trump’s guilt was all but certain?

It’s no exaggeration to say that Barr’s promise to investigate the investigators sets the stage for fundamentally changing the narrative from the one the media fed the nation for two years.

Even at this early stage, Trump looks stronger than ever and Dems are mad with frustration.

Many are furious with Barr, with some hysterics saying they want to remove him from office, as if somebody must be impeached. CNN, NBC and others are accusing Barr of doing Trump’s “dirty work” by daring to use the “spy” word, as if straight talk is too much for their tender sensibilities.

They are so in the tank against Trump that they denounce the search for truth because the truth might ­favor the president.

Those with the most skin in the game are the most at risk, starting with Jim “The Snake” Comey. The former FBI director, whose conduct makes J. Edgar Hoover look like a choirboy, claims he is confused, saying “I have no idea” what Barr is talking about.

James Clapper and John Brennan, the intelligence chiefs under Obama who came out of the closet as naked partisans, added their two cents of shock. “Stunning and scary,” Clapper said of Barr’s plans, and Brennan accused Barr of sounding like a “personal lawyer” for Trump.

Translation: we better lawyer up.

Meanwhile, Mueller, the would-be savior, is now a nobody, an afterthought in the Dems’ river of rage.

Other recent developments also favored Trump. The economy continues to roar and the crisis on the border that Dems said didn’t exist clearly does, with illegal crossers numbering more than 100,000 a month — and those are just the ones apprehended.

Trump is at least searching for solutions while Dems have closed their eyes and ears to a security and humanitarian nightmare, as if it is just an inconvenient distraction.

Trump was also a winner in the Israeli election, with his support of Bibi Netanyahu helping to lift the prime minister to victory.

While there is personal satisfaction for both men, the greater truth is that stability in Israeli politics removes any Palestinian fantasy that a dovish new prime minister would return to the lifeless land-for-peace formula. Arabs — and Iran — can either deal with Trump and Netanyahu, or waste more time and lives weaving their dream palaces.

Democrats, in reaction to the Trump-Netanyahu alliance, continued to move away from Israel. All the 2020 candidates skipped the AIPAC conference and Beto O’Rourke called Netanyahu a “racist.”

Finally, Rep. Ilhan Omar is proving to be a one-woman wrecking crew for the party as well as for the image of all American Muslims. On top of her anti-Semitism, Omar’s dismissive description of 9/11 as “some people did something” marks her as a heartless ingrate to the nation that rescued her family from civil war and possibly death at the hands of other Muslims.

The only question is whether party leaders will have the courage to stand up against her. Sen. Chuck Schumer and Speaker Nancy Pelosi are usually camera hogs, but ducked questions about Omar’s 9/11 reference and her claim that criticisms of her are anti-Muslim.

They did, however, find time to criticize Barr’s plan to investigate the investigators, thus proving again that Democrats have the leaders they deserve.

Taking Idiot at his word

The scores of sordid criminal charges against Michael Avenatti wouldn’t be news if the media hadn’t turned him into a weapon against Trump. He appeared on CNN and MSNBC nearly 200 times to push his Stormy Daniels case — and to launch his presidential hopes.

Did anybody at those networks vet the guy? Did they ask former clients if he was honest?

Of course not. He was their useful idiot until he was no longer useful.

Warning ‘label’

Reader Evilio Herrera is fed up with Schools Chancellor Richard Carranza, writing: “I’m tired of his ‘racist’ labeling. The man obviously has a complex. As a Latino American myself, the race card game has gotten old.”

‘Bandwagon’ stuck in park

A headline in The New Yorker says Sen. Kirsten Gillibrand’s 2020 campaign has “stalled.”

Wrong. She hasn’t stalled. She was never moving.