Unfortunately, acts of destruction and terrorism aren’t as big of a surprise anymore. Nineteen years ago, though, it was.

It’s not hyperbole to suggest that we can sharply divide the history of America’s national security into two eras: before 9/11 and after 9/11.

Today — albeit differently than the past 18 years — Southern Marylanders will join the nation as we remember the 2,996 lives lost in the terror attacks of Sept. 11, 2001, including 343 firefighters and 72 law enforcement officers. More than 6,000 others were injured. It was the deadliest day in U.S. history for first responders.

And in many ways, it changed us all. Forever.

Most of us remember where we were that day and what we were doing.

That awful morning, terrorist hijackers deliberately crashed two commercial jets into the Twin Towers of the World Trade Center in New York, and a third into the Pentagon. A handful of brave passengers stormed the cockpit of a fourth airliner and fought the terrorists, ultimately crashing the jet into a field in western Pennsylvania before it could turn into another guided missile.

When the first crash happened into the north tower, it seemed like a freak accident. How could air traffic control go so wrong? Had the pilot suffered some sort of medical emergency? What could have happened?

But when the second airliner slammed the south tower, all doubt was removed — this was intentional.

It was in the days before social media, so for those not already tuned in and unable to look away from the television that day, there were phone calls telling us to turn on the news. We witnessed the shock and horror of the video and photos of the attack and the subsequent collapse of the Twin Towers. We made efforts to reach friends and loved ones feared to be in harm’s way, all the while trying to make sense of what was happening, and hoping it was over.

Then came the news that hit Southern Maryland most directly. Another jetliner — American Airlines Flight 77 — had crashed into the Pentagon, killing nine people from this area among the 125 who perished there.

Those nine were:

• Kris Romeo Bishundat of Waldorf was 23, a Navy petty officer who had been assigned to the Pentagon just three months before the attack;

• Donna Marie Bowen of Waldorf was 42, a Verizon telephone worker assigned to an Army budgeting office;

• Sharon S. Carver of Waldorf was 38, a civilian accountant for the Army;

• Angela M. Houtz of La Plata was 27, a civilian analyst with the Office of Naval Intelligence;

• Shelley A. Marshall of Marbury was 37, a budget analyst with the Defense Intelligence Agency;

• Gerard P. “Jerry” Moran Jr. of Upper Marlboro was 39, an engineering contractor with the Navy and softball and powerlifting coach at St. Mary’s Ryken High School;

• Marvin Roger Woods of Great Mills was 57, a retired Navy communications chief who worked as a civilian communications specialist at the Pentagon;

• John D. Yamnicky Sr. of Waldorf was 71, a retired Navy test pilot who was a passenger aboard the airliner; and

• Edmond Young Jr. of Owings was 22, a civilian technician who was assisting a general with a computer problem when the airliner struck the building.

We remember them, and we honor them.

Please take a moment today to recall these five men and four women from Southern Maryland who lost their lives that day, among so many others, as well as the sacrifice and bravery of firefighters and law enforcement officers, and regular civilians.

Also, take a moment to reflect on the national unity and resolve that so touchingly developed 19 years ago in the wake of the worst terror attack on American soil.

Those who do remember that day remember what happened to America in the days following. America was united. Sure, we had differing opinions on how to respond or why these attacks happened in the first place. It’s not like you can get hundreds of millions of people to agree on everything. But the one thing most people in the country agreed on was that we are America, we are resilient and we would overcome this tragedy together.

Remember in these times of strife and unrest, that we are, and always have been, more alike than we are different. Perhaps we need that reassurance now more than ever.