The 10th anniversary of the September 11, 2001 terrorist attack brought all manner of people to the streets of New York City Sunday to mark the opening of National September 11 Memorial & Museum at the World Trade Center, where the amplified reflections of people who lost loved ones echoed beneath an overcast grey sky.

But particularly conspicuous were the men and women in uniform. Some of them lost friends and comrades on that day, while for others it was a formative experience that encouraged them to serve their country.

A Day For America To Unite

Ben Pearce, a 20-year-old midshipman second class at Fort Schuyler in the Bronx, was in fifth grade when his English teacher announced the attacks. The freshly pressed uniform he wore on Sunday was a direct product of September 11, he said.

I decided that if there's people that want to make reckless decisions and kill innocent people then it is my duty as an American to serve, Pearce said. He also sounded a hopeful note about the people gathered to commemorate the tragedy.

Americans are bad at finding good in situations where evil prevails, Pearce said. Today is a day when every American -- Christians, Jews and Muslims -- can come together.

Joseph Apuzzo, a retired deputy chief for Emergency Medical Services, called 9/11 the worst day of my life and said it snapped into sudden focus the risks he took on when he chose to serve.

They talk about post-traumatic stress, there's also post-traumatic growth, Apuzzo said. These things cause you to become more introspective. It sharpens the lens on your life. When it all stops, when the pin drops, you take a second and realize it could be your last day, any day you go in.

New York City Fire Fighter Loses Best Friend

Others traveled from farther afield to pay tribute. Eard Trimmingham, now a deputy sheriff in Richmond County, Georgia, was a fireman in New York 10 years ago. He was fortunate enough to have the day off but said that his best friend, a Port Authority police officer, was killed. Trimmingham said he was comforted by the progress made in raising new skyscrapers out of the wreckage of ground zero, adding that living through the attacks and continuing to work as a New York City firefighter until he resigned in 2005 strengthened his convictions about the work he had chosen.

It is what I do, Trimmingham said. I think this has been my calling since I was a child.