It will go down as the day that lives in infamy, our generation’s version of Pearl Harbor except worse.

We will tell our grandchildren about September 11, 2001, the same way we were reminded of Pearl Harbor by the previous generation.

When it came it blotted out our sun and caused America to lurch into a state of deep crisis. Even a decade and a half later the wars in Iraq and Afghanistan, still claiming lives, are a testament to how horrific the aftermath is.

It was the day that America lost its innocence, the day that we realized we could be attacked by militant maniacs who thought nothing of killing thousands of innocents.

They came with hate in their hearts and left behind a devastated country. Even now the scale of the massacre is hard to take in.

The victims speak to us across the years, their faces pinned in our memory as surely as those of relatives closest to us who have passed.

Read more: 9/11 attack on World Trade Center seared my soul

They ranged in age from 2-year-old Christie Hanson and young 4-year-old Juliana McCourt, who died with her mother Ruth from Cork, on their way to Disneyland, when their plane was hijacked, to the oldest Robert Norton, aged 85.

In between was a cross section of American life of ordinary people caught up in a horrible nightmare that a decade and a half later is still hard to fathom.

The hijackers carried with them what WB Yeats called “fanatic hearts,” and turned “hatred into sport.”  The results were horrific.

At Pearl Harbor at least the target was military. The 3,000 killed on 9/11 were innocent civilians or uniformed police and fire officers trying to help save lives.

When death came calling on that perfect September day it took victims from every conceivable walk of life.

The individual memories have faded in many cases, but for the families concerned this 15th anniversary is yet another reminder of what happened their loved ones that tragic day.

How many lonely days and nights they must have spent never hearing or seeing loved ones again. The 15th anniversary again allows a communion for the American masses with those who died, but for those individually affected the pain never ends.

The Irish American community was deeply affected by the atrocity, from the hundreds of firefighters and cops who perished to the many Irish on Wall Street, many of whom who were the successful offspring of an earlier generation of cops and firemen.

We can remember the wakes, the incredible outpouring of love and respect for young men like Damian Meehan and his Donegal family, to the amazing religious service for Mychal Judge, the Irish priest whose parents came from Keshcarrigan in Leitrim and who became the face of the tragedy.

Read more: Remembering Father Mychal Judge and our other heroes of 9/11

The Franciscan Father Judge was a man who spread peace and love wherever he went. He visited Northern Ireland many times with hero NYPD Officer Steven McDonald in efforts to further the peace there.

There were hundreds who died like Father Judge, and firemen and police officers who had given over their life to help others before they were killed.

The legacy of 9/11 is everywhere, even in the warning this week for Americans to be on guard when they travel overseas, and the massive security measures at our airports.

We soldier on, a wearier world and one far less safe since 9/11. We pay tribute, not because we have to but because we want to.

We know that it could have been any of us that awful September day 15 years ago. Let us hope no other generation will ever have to bear such a burden of such an awful day.