Here’s a brief but sadly necessary history lesson.

On Oct. 7, 2023, Hamas’ marauders crossed over from Gaza into Israel, murdered more than 1,200 innocent civilians, kidnapped hundreds more, raped women and beheaded children.

Responding to the attack, and striving to rescue the hostages, the Israel Defense Forces began a limited ground operation in Gaza six days later, on Oct. 13.

The Israeli army then took another two weeks to launch its full-force assault on Hamas, which began on Oct. 27.

And yet all over America, from Midtown Manhattan to Stanford’s leafy campus, the crowd calling itself “pro-Palestine” chose Oct. 7, specifically and deliberately, as its “Day of Action.”

Leaflets shared anywhere from social media to city lampposts show a host of masked Hamas terrorists, fresh from the killing fields, flashing victory signs.

The caption calls on supporters to show up “for our martyrs.”

This decision speaks volumes.

The thugs who took to the streets on Tuesday weren’t supporting Gazans or mourning the loss of Palestinian lives.

They were celebrating the massacre of Israeli Jews, and letting Americans know that we’re next in line.

If that sounds alarmist, consider what an actual pro-Palestinian demonstration might’ve looked like.

For two years, the pro-Palestine camp had a two-word list of demands: Cease-fire now.

When President Trump last week finally negotiated a successful cease-fire deal involving the immediate return of all hostages, Israel signed on right away.

So did virtually all Arab nations.

Hamas, unsurprisingly, was the sole holdout: The terror group continues to alter its list of concessions and demands.

Anyone who truly wants peace, anyone serious about alleviating the suffering, ought to have protested and demanded that Hamas sign the deal right away.

Instead, the loudest pro-Palestine voices, including Rep. Rashida Tlaib (D-Mich.), blasted Trump’s initiative and called on the Palestinians to reject it.

It figures.

The defensive operation Israel’s rabid detractors are outrageously calling a genocide could’ve ended a long time ago.

It could’ve ended with a simple decision to free the innocents withering away in Gaza’s terror tunnels, starved and tortured and denied access to medicine and food.

It could’ve ended with Hamas surrendering, laying down its arms and letting the rebuilding of Gaza begin.

It could’ve ended with the people of Gaza themselves demanding that the terrorists who brought on so much misery and destruction on their own people be brought to justice.

Instead, all we heard from those who purport to support Palestine is more calls to punish Israel — and all we saw is more violent protests and attempts to disrupt everyday life everywhere from New York to Barcelona.

Because the violence and the disruption are exactly the point.

Hamas and its sycophants around the world aren’t interested in peace or prosperity.

They care only about destroying the infidels, a term they apply to Israelis, Americans and anyone resisting their homicidal fantasies of world domination.

That’s the reason they’ve been targeting all-American events like the Rockefeller Center Christmas Tree lighting ceremony or the Macy’s Thanksgiving Day Parade.

It’s also the reason they chose to celebrate Oct. 7, the date commemorating the launch of their war on Western civilization.

You’d hope that, at the very least, the man likely to become New York’s new mayor would know better than to cheer on this demented bloodlust.

Zohran Mamdani failed this simple test miserably, releasing a statement thick with terms like “apartheid” and “occupation” and calling for more sanctions against the Jewish state.

We deserve better.

On the ballot, in the press, in the classrooms, in the streets, we must let the goons know that the battle they picked on this day two years ago is one they’re never going to win.

Liel Leibovitz is editor at large for Tablet and senior fellow at the Hudson Institute.