Fifty years ago Friday, five men were arrested for burglarizing the Democratic National Committee at the Watergate complex. That set off a sad chain of events that changed the course of American history — and gave rise to an increasingly leftist ruling class that’s weaponized key institutions, including the press, national-security apparatus and law enforcement, to achieve its ends.

When I served as foreign-policy assistant to President Richard Nixon during his last years, we’d discuss Watergate occasionally. As the 20th anniversary of the break-in approached, he recalled the radicals’ hostility toward him, ascribing it to his role in exposing and prosecuting establishment darling Alger Hiss as a Soviet spy — which also raised the explosive question of Communist influence in the government — and his handling of the Vietnam War.

“Those who were after me,” he said to me, “weren’t interested in Watergate as much as they were interested in getting me on Hiss and on Vietnam. I gave them what they needed, but believe me, Watergate was just the excuse.”

“Are you saying that if it weren’t Watergate it would have been something else?” I asked.

“That’s my theory,” he replied. He believed that since he was immune to the intellectual viruses of the leftist elites, they had to bring him down.

This is not to excuse Nixon’s behavior. His central role in the coverup — for which he accepted full responsibility — torpedoed his presidency.

He later admitted to having been blind to the threat he posed to entrenched establishment power. “There are standards for Democrats, standards for Republicans; then there were standards for me. I was in a totally different category,” he told me. “I should have known that I . . . couldn’t even sneeze . . . without someone ordering an investigation. So to that extent, I was stupid.”

After they claimed Nixon’s scalp, these newly emboldened forces ramped up their efforts to undermine leaders they considered obstacles to their agenda: Presidents Ronald Reagan, George H.W. Bush and George W. Bush. Soon they sought to crush all opposition, particularly those they could not control, ferociously attacking Supreme Court nominees such as Robert Bork, Clarence Thomas and Brett Kavanaugh — and even average Americans attending Tea Party protests, Trump rallies or school-board meetings.

This required turning critical institutions against us. The Justice Department and FBI became dangerously political, operating a two-tiered justice system in which wrongthinkers (like Gen. Michael Flynn and nonviolent Jan. 6 protesters) are disproportionately punished while leftist elites (like Hillary Clinton and Michael Sussmann) skate. As the outsider who spurned the corrupt establishment in favor of hardworking Americans, Donald Trump represented an existential threat. So these rotted organizations knowingly perpetuated the Russia hoax against a sitting president, crippling America in the process, and buried the truth about Hunter Biden’s laptop.

Now they’re targeting parents for defending their kids. The radicals also weaponized education to indoctrinate children to hate America and embrace socialism, critical race theory and abusive sexualization.

The media openly work hand-in-glove with the left and Big Tech to silence speech, cancel dissenters and memory-hole truth. And the culture is directed by a nearly monolithic leftism; witness Disney’s disastrous foray into woke virtue-signaling.

This modern cycle of national destruction began when the radicals saw an opportunity to take Nixon out. Though he was often derided as paranoid, Nixon had real enemies committed to his destruction, and he was equally committed to counterattacking, resulting in a harrowing dance of mutual annihilation.

Sound familiar? Those same dark forces will continue to wage ruthless war on anyone else who challenges their unaccountable power and corrupt status quo.

Watergate cast a large shadow over American politics and deepened an existing culture of political mistrust, to be sure. But it also normalized the criminalization of policy differences that has corroded our institutions and accelerated a dangerous tribalism that threatens our national cohesion. As a result, the left and its ruling-class handmaidens have felt increasingly empowered and justified in using all necessary means to achieve their ends.

The break-in’s 50th anniversary will give the press a fresh opportunity to resurrect the long-ago scandal while minimizing current outrages, from skyrocketing inflation and gas prices to the open southern border to Biden family corruption. The left’s long march, turning our institutions into weapons of ideological war and torching any opposition along the way, rolls on. In retrospect, it’s clear their success in removing Nixon supercharged their mission.

Monica Crowley is the host of the Monica Crowley Podcast.