Correction: The article about a Veterans Day observance said that both President Obama and Maj. Gen. Michael S. Linnington put their hands on their hearts as a military band performed “The Star-Spangled Banner.” The president did so, but Linnington saluted the American flag. This version has been corrected.

A single soldier walked alone, 21 steps, back and forth, back and forth. His watch: the Tomb of the Unknowns. The only noise came from the clack of his polished shoes and the click of visitors’ cameras.

Silence here is usually the ceremony.

But on Sunday, at the 11th hour on the 11th day of the 11th month, the solitude of the soldier and the tomb gave way to a swarm of grateful Americans. Members of the military past and present and their friends and family members had come together to pay their respects in a Veterans Day observance led by President Obama.

Sunday’s event had special significance: For the first time in a decade, the nation was no longer at war in Iraq. And it was only the second observation in a world without any living U.S. soldiers who fought during World War I.

In the amphitheater in front of the Tomb of the Unknowns, members of the U.S. Navy chorus sang hymns thanking God and praising their country, their sound soaring through the sky. Soldiers arrived in formation after their steady, rhythmic march through Arlington National Cemetery.

The guests buzzed about how brilliant the morning was, sunny and 10 degrees warmer than the year before, with autumn leaves just beginning to rest between headstones of the fallen.

As the ceremony’s 11 a.m. start approached, the leader of the 3rd U.S. Infantry Regiment shouted “Ready!” and his troops began to march. They were joined by ceremonial guards from the Marines, the Navy and the Coast Guard, along with the Air Force’s Honor Guard.

Front, back, left, right — the unknown soldier was surrounded.

To the left, a 35-member Army band had also marched to the tomb, instruments in tow.

Then, in the distance, the sound of a cannon blast. Then 20 more.

Then, a voice boomed over a loudspeaker: “The president has arrived.’’

Obama entered stage right, alongside Maj. Gen. Michael S. Linnington, commanding general of the Joint Force Headquarters’ National Capital Region. President Obama put his hand on his heart and Gen. Linnington saluted the American flag as a military band played a brassy national anthem. Taps was sounded.

On these hallowed grounds just a few minutes after the 11th hour, Obama — known for his skilled oratory — made no reference to his reelection five days earlier.

He said nothing. A sergeant marched 21 steps to greet him. Together, they lifted a large wreath and laid it on the tomb honoring a single unidentified soldier — and all those who’ve served in U.S. wars.

The president simply bowed his head, asked the audience to do the same and led this mass of the patriotic in 30 seconds of silence.

Later, speakers at the amphitheater congratulated Obama on his hard-fought election victory, and the president found his voice.

He talked about the need to continue support for the GI Bill and spoke of his administration’s successes in training returning troops for new jobs and increasing the Veterans Affairs budget.

Of all his responsibilities as president, he said, nothing was more humbling than meeting those who serve the country. “The real heroes,” he called them.

“Tour after tour, year after year,” Obama said, “you and your families have done all that this country can ask.”