Every generation has its “Where Were You When…?” dates. For my parents’ generation — the most poignant “where were you when” question is the assassination of President John F. Kennedy on November 21, 1963. The moment that, for each American who heard that awful news, is forever seared in their memories.

In my generation’s childhood years, the main such moments were hearing that President Ronald Reagan had been shot, and five years later learning that the space shuttle Challenger had exploded. Those were my generation’s defining dates — until Sept. 11, 2001.

That day I was in Washington, D.C. I had just moved back three weeks earlier, returning after a three-year hiatus for graduate school to the city where I had previously lived and worked for several years. My daily commute took me right past the Pentagon, just 200 yards from the spot where the hijacked American Airlines Flight 77 would tear a hideous gash into the building. 

On that morning I left the house around 6:45 a.m. for a breakfast meeting on Capitol Hill. Never would I have imagined that within three hours of driving by, the Pentagon would become the first Washington building attacked in wartime since the British burned the city almost two centuries earlier.

After my breakfast I parked my truck on Capitol Hill and took the Metro to my office at the American Enterprise Institute, a think tank six blocks from the White House. Shortly after arriving at my desk, one of my interns came over with a quizzical look and said that an airplane had just hit the World Trade Center. Curious, I opened the Washington Post website to a headline saying the same thing but offering no details. My immediate guess was that a small private plane must have accidentally collided with the building. Assuming there was nothing more to the story, I resumed work. 

A few minutes later my intern came running back and said that a second plane had hit the other World Trade Center building. Almost simultaneously, another colleague yelled that “the Pentagon has been hit, we are under attack!” It was simultaneously frightening and surreal as I tried to make sense of the discordance between the possibility that we were in our last minutes of life and the fact that our office felt as comfortable and placid as any other day. There was no smoke or fire, no clanging alarms, no gunshots, no masked men yelling — none of the things that I assumed an attack would bring. 

All that changed minutes later when a few colleagues and I went outside on the roof of our building. Across the river, a black pillar of smoke buried the Pentagon and stretched miles into the sky, magnitudes larger and more terrifying than any fire I had ever seen. I ran back down to my desk and phoned my parents in Tucson. When my mother answered I quickly blurted, “Mom, I just want you to know that I am OK.”  Bewildered, she asked, “What do you mean?” Realizing that Arizona was three hours behind the East Coast and she had just woken up, I told her to “turn on the TV, we’re under attack, I love you and will call back later!”

Now chaos and confusion set in. Someone else ran over and reported that the State Department had just been hit. Another person said that a bomb had just been set off at the Washington Monument. Yet another said that gunmen were attacking the White House. 

None of that was true, yet at the time we did not know, and given the smoke from the Pentagon descending across the rest of the city, any terrible report seemed possible. Nor did we know that in these same moments, the heroic passengers of hijacked United Flight 79 were sacrificing their lives to prevent their plane from decimating another Washington target, perhaps the White House or the Capitol.

I ran into the office of another colleague. He and several others were huddled in front of the television, watching live footage from New York. Suddenly we saw the first tower begin to crumble and fall. None of us said a word; tears rolled down several faces.     

The building manager said it was our choice whether to evacuate the building or stay in place.. Along with many others, a friend and I decided to leave. Outside, a surreal scene confronted us. The streets were packed with thousands of people, deathly quiet, walking with faces pale in collective shock. Uniformed men with assault rifles sternly motioned us down certain streets. We walked for almost three hours until reaching my truck, parked near my church on Capitol Hill. I went inside the pastor’s office where he and several others were watching the news. There we stayed for about six hours, transfixed and horrified. As evening fell the vehicle ban was lifted, so I began to drive home. Minutes later I passed by the Pentagon again, smoke billowing out amid the carnage and rubble. I knew that nothing would ever be the same.

Inboden is executive director of the Clements Center for History, Strategy, and Statecraft, and associate professor at the LBJ School of Public Affairs.