Senior Pentagon leadership, including Joint Chiefs of Staff Chairman Gen. Mark A. Milley, joined a pre-dawn ceremony today commemorating the September 11, 2001, attacks, which included the unfurling of Old Glory at the side of the five-sided Defense Department headquarters.

Many standing in the rain outdoor ceremony were military personnel assigned to the Pentagon, survivors of the Pentagon attack, family and loved ones of those killed, and representatives from the local police and fire departments that responded to the attack.

The giant American flag was hung on the building from the roof by workers with the Pentagon’s Building Management Office, led by David Brown, who earned the Medal of Valor for his contributions to the recovery from the attack that morning. 

Pentagon Family Life Chaplain Maj. Mark McCorkle delivered the invocation:

Let's pray Almighty today we acknowledge you as the Creator and Sustainer of the world. We humbly come before you with gratitude and honor and allowing all of us to be here representing the freedom of the United States of America. 

The price of freedom cost many lives that served on this hollow ground. It is with that love for country. We also stand today with family and friends who have lost one of our own. Let this place and this day be a reminder of the resolute and resolve we all have to honor our highest who gave their lives 22 years ago for the finest country in the world, the United States of America. In your Holy Name, we pray, Amen.

Pentagon Police Sgt. Anthony Brecht sang the National Anthem at the ceremony. NCIS Special Agent Michael McLean, a City of Alexandria Pipes and Drums member, closed the 10-minute ceremony with "Amazing Grace."

The Pentagon was struck by a Boeing 757, American Airlines flight 77, piloted by al-Qaeda terrorist Hani Hanjour. The flight took off from Dulles International Airport at 8:20 a.m., heading for Los Angeles. It instead struck the building at 9:37 a.m. 

The airliner struck the E Ring at the first deck level between Corridors 4 and 5, and then the plane continued to slide through the building until it settled between the C and B rings. The fires continued to burn for more than a week.

Hanjour and his cohorts hijacked AA 77 somewhere over the border of West Virginia and Ohio. 

Sixty-four passengers and 125 military and civilian personnel were killed in the crash.

One of the rescuers at the Pentagon was Hospital Corpsman Chief Petty Officer Darrell Hamilton, who had just reported to the Pentagon on August 4, 2001, from USS Enterprise. Hamilton was at a Quantico, Virginia, golf course when he heard the impact of the 757 into the Pentagon’s west side. 

Hamilton learned what had happened and reported to Maryland's Bethesda Naval Hospital, where he expected to assist with injuries. However, most of the injured were sent to local Arlington, Virginia, facilities. 

The next day, Hamilton reported to the Pentagon to join the search and rescue, and then recovery missions.

I had been around deaths before from the USS Enterprise and throughout my time in the Navy as a corpsman in hospitals and dealing with patients. This situation was a little bit different due to the fact that these were charred remains—you couldn't even call them bodies. It was something you had to get your frame of mind situated to work with. There was no flesh. Nothing to identify the bodies. It was kind of rough dealing with that. It was a whole different perspective—a whole different outlook on things.    

I was involved in plane crashes on the USS Enterprise flight deck and had seen some grotesque things, but nothing as close to what I saw at the Pentagon on the 12th of September. That is a very sobering experience.

In addition to AA 77, al-Qaeda terrorists hijacked three other flights. 

American Airlines Flight 11 took off for Los Angeles from Boston's Logan Airport at 7:59 a.m. and crashed into the North Tower of New York City's World Trade Center. 

United Airlines Flight 175 also took off from Logan at 8:14 a.m. for Los Angeles and crashed into the World Trade Center's South Tower.

United Airlines Flight 93 took off from Newark International Airport at 8:42 a.m. for San Francisco and crashed into a field near Shanksville, Pennsylvania. Flight 93 is celebrated for the mutiny the passengers raised against the hijackers. The flight was delayed for roughly 40 minutes, and by the time the terrorists took over the airliner, the passengers learned about the other airliner attacks. 

The mutiny took place at or around 9:57 a.m. during the struggle for control of the 757; the plane crashed into the field. 

At the Pentagon, word of the UA 93 led to an evacuation of the building as first responders and other personnel were engaging the fire and search and rescue for survivors from AA 77.

The UA 93 mutiny took down the airliner as it was 20 minutes from Washington, leading to evacuations at the White House and Capitol Hill.