The 25th anniversary of the horrific events of 9/11 will be, as it must, a somber reminder of those we lost on the deadliest day in American history.

The reading of the names of the fallen and the tolling of the bells are rites that never grow old. They vividly remind New Yorkers and the world of the ultimate price 2,753 innocent people paid that day in the Twin Towers, on the ground, in nearby buildings and in the two hijacked jet liners.

Nearly 200 other innocents perished when a third hijacked plane smashed into the Pentagon, and 40 passengers were killed when they heroically fought terrorists on a fourth jet that crashed in Shanksville, Pa.

The Manhattan ceremony at the site known around the world as Ground Zero will properly salute the undaunted courage of hundreds of firefighters and police officers — the Bravest and the Finest — who perished while valiantly trying to save others.

National unity

Remembered, too, will be the crews and passengers of the two giant airliners seized by terrorists and flown into the buildings.

The immediate impact was an ocean of shock and anger that quickly forged a rarely seen national unity. A fervor of patriotism previously reserved for world wars and national calamities swept the nation.

Yet as time passes, events shaped by the attacks and the aftermath also must be included to gain a more complete picture of that historic day.

Most tragically, a total of 9,677 first responders and survivors have died from 9/11-related illnesses, according to federal data, meaning those deaths far exceed the number of fatalities from the actual attacks.

Most have died from various cancers related to the toxins released by the collapsing and burning of the skyscrapers. Reports say that in total, more than 57,000 cases of cancer that can be traced to the aftermath have been documented.

Just as the attack dramatically heightened the national awareness of Islamist terrorism and led to the wars in Iraq and Afghanistan, the devastating health fallout continues to roil our society.

In hindsight, it was inevitable that the spirit of unity in Washington and New York would give way to a politics scrambled by different ­reactions to the attacks on America.

The word “homeland” was not commonly used until then, but events gave birth just a few days later to the federal Department of Homeland Security. It was formally created by a wave of bipartisanship in Congress as a stand-alone agency the following year.

Its mission has grown dramatically, and is now described on its website as being “to secure the nation from the many threats we face.” It has some 260,000 employees covering aviation and border security, emergency response as well as cybersecurity.

Yet increasingly, the soaring cancer rates and related findings in and around Ground Zero have sparked pointed questions about what the various levels of government knew and when they knew it.

Reckless claim

The questions are legitimate and deserve answers. But what is illegitimate is the reckless, unproven claim that Rudy Giuliani and every mayor since him has been part of a conspiracy to hide deadly truths from the public.

That was the tone and substance of Mayor Mamdani’s rant at City Hall Tuesday when he announced the creation of a public portal and the release of 170,000 pages of post-9/11 information.

“People got sick because the leaders they trusted lied and told them they were safe to breathe in toxic air. And then, when they began to contend with the symptoms of the illnesses that followed, the government that had not hesitated to send them into harm’s way was nowhere to be found,” he declared.

It sounds as if, had he been mayor, the ruins would still be there and no rebuilding of the site would have taken place.

As always, his “facts” are distorted by ignorance and bias. The smoldering pile was obviously unhealthy, but state-of-the-art breathing-protection equipment was scarce for the scale of the operation, and some uniformed searchers, in their grief and fury, refused to use the equipment that was available.

For Mamdani and his socialist troops, the sudden concern is the political equivalent of a lawyer who chases an ambulance after an accident in the lust for a big payday.

Because he is the ultimate outsider now running the inside, it is impossible to escape the suspicion that Mamdani is latching on to the open wounds of 9/11 to boost his sketchy standing.

Consider that he is the subject of a petition signed by more than 102,000 people urging him to stay away from Friday’s ceremony.

The signers include many who lost friends and family in the attack and aftermath.

The mayor has only himself to blame for the opposition, in that he came of age politically in the anti-police wave that started under Barack Obama’s presidency. Mamdani swallowed and repeated the “all cops are racist” smear, hook, line and sinker.

And at just age 34, the city’s first Muslim mayor did not help his cause by hanging out with Hasan Piker, the radical social media star who declared that “America deserved 9/11.”

Called on his association, Mamdani suddenly declared Piker’s comments “objectionable and reprehensible.”

Damning predecessors

Still, his glib damning of all recent mayors omits any federal responsibilities on air-quality issues, which rests with the Environmental Protection Agency.

If documents were hidden by the feds since 9/11, that would span the terms of every president, from George W. Bush to Donald Trump, and including Obama and Joe Biden.

And what about Albany? Mamdani’s new best friend, Gov. Hochul, has been in office for five years. Are her hands clean on the charge of concealed air quality findings?

More likely, his Tuesday speech was just another partisan attack meant to detract attention from Mamdani’s own thin record on terrorism and his hatred of Israel. Whatever the world’s problems, he is among those who instinctively blame America first.

His experience and ideology blind him to a fear that many New Yorkers had for days and even years after 9/11. It often seemed as if another, even larger attack on the city was inevitable.

I was among those people and, in a private conversation, confessed my fear to Ray Kelly, during his term as Mayor Bloomberg’s police commissioner. Kelly was taken aback, looked sternly at me and said, “I don’t believe that. It’s not inevitable.”

I was embarrassed, then relieved to realize how dedicated he and so many others were in making sure there was no second ­attack.

Thankfully, they succeeded and there is every reason to believe that Kelly’s resolute attitude continues at Police Plaza under his protégée, current Commissioner Jessica Tisch.

Is City Hall on the same page? I wish it were but I fear it is not.