Obama: Decade Since 9/11 a Story of American Resilience

President Barack Obama speaks at 'A Concert for Hope' at the Kennedy Center in Washington. (AP)

President Obama, recalling the uncertainty and grief that struck a nation suddenly thrust into war, said Sunday that the decade since the Sept. 11 attacks has underscored America's resilience in the face of trial.

Speaking at a memorial concert in Washington, the president closed a day of services to honor the nearly 3,000 who died with a call to "rededicate ourselves to the ideals that define our nation." Looking back, Obama said those ideals and the character of the country withstood a historic test.

"It will be said that we kept the faith, that we took a painful blow, and we emerged stronger than before," Obama said at the Kennedy Center.

The president, as he did during several visits to Sept. 11 memorials throughout the day, paid tribute Sunday night to the soldiers, diplomats and intelligence officers who have served overseas since the attacks. He said the past decade has shown America "does not give in to fear." Yet, saying America's strength will be measured by its commitment to ending those conflicts that emerged from the attacks, he cited "our desire to move from a decade of war to a future of peace."

The memorial service and concert in the capital capped a national day of remembrance, as Americans everywhere honored the memories of those who died and rekindled the sense of unity that cut through the sorrow that day.

At Ground Zero in lower Manhattan, at the Pentagon and in a field in rural Pennsylvania, families observed moments of silence to commemorate when and where Al Qaeda inflicted a day of terror on America. They told stories of those who died. They waved flags and read from Scripture. They did their best to honor the first responders who saved lives -- and in some cases gave their own -- and the members of the U.S. military still fighting.

"The true legacy of 9/11 is that our spirit is mightier," Vice President Biden said outside the Pentagon, the flag draped over the wall behind him. He said the attacks galvanized a "9/11 generation of warriors" to fight back.

Obama spent his day traveling to the three sites, visiting first the World Trade Center memorial and then the site in Shanksville, Pa., where Flight 93 crashed after its passengers wrested the controls from hijackers bent on attacking a third U.S. landmark. During the stop, the president spoke at length with family members of victims and helped place a wreath at the Wall of Names honoring the dead. Later at the Pentagon, he and first lady Michelle paid their respects at the memorial marking the place where 184 people died. The president kept a low-key presence, shaking hands and posing for pictures with family members of victims, eliciting smiles from onlookers at the end of an emotional day.

The ceremony at Ground Zero ended Sunday afternoon with the playing of taps -- after relatives read aloud the names of those who died.

The heart-wrenching ceremony was punctuated by musical performances -- from Paul Simon, Yo-Yo Ma and others -- and by remarks from family members. Peter Negron devoted a few minutes to honoring the memory of his father, Pete, who died in the World Trade Center attacks. "I wish my dad had been there to teach me how to drive, ask a girl out on a date, and see me graduate from high school," he said. "I miss you so much, dad."

Nicholas Gorki remembered his father, "who I never met because I was in my mother's belly. I love you, Father. You gave me the gift of life, and I wish you could be here to enjoy it with me."

In a scene similar to that which unfolds at the Vietnam War memorial in Washington, D.C., every day, relatives walked up to the newly opened memorial at Ground Zero and placed pictures and flowers by the victims' names.

New York Mayor Michael Bloomberg started the service with a moment of silence citywide at 8:46 a.m. ET, when Flight 11 struck the North Tower a decade ago.

"Ten years have passed since a perfect blue-sky morning turned into the blackest of nights," Bloomberg said Sunday morning. "Since then, we've lived in sunshine and in shadow."

After a reading by Obama from Psalm 46, more than 300 people stepped to the podium throughout the day to read out the names of loved ones.

Former President George W. Bush also read from a letter Abraham Lincoln wrote to a Civil War widow 150 years ago.

At the Pentagon, the American flag was unfurled over the side of the building at dawn. Dignitaries observed a moment of silence at 9:37 a.m. ET, the time when that building was hit. Each of the Pentagon victims has been memorialized with a bench and accompanying reflecting pool.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, said the attacks proved that while America's enemies could kill its citizens, they "could not kill our citizenship." He praised the 2 million men and women who have deployed since the attacks.

"All of them have remained dedicated to making sure a day like that never happens again," Mullen said.

In what Biden described as a "stark and vivid reminder this war continues," a Taliban truck bomb struck a U.S. base in Afghanistan on the eve of the anniversary, wounding nearly 80 American soldiers and killing two Afghan civilians. Amid the chaos, coalition forces were conducting a memorial service in Afghanistan Sunday morning.

At the dedication of the Flight 93 National Memorial near the town of Shanksville on Saturday, former Presidents George W. Bush and Bill Clinton and Biden joined the families of the 40 passengers and crew aboard the jet who fought back against their hijackers.

"The moment America's democracy was under attack our citizens defied their captors by holding a vote," Bush said.

The passengers and crew gave "the entire country an incalculable gift: They saved the Capitol from attack," an untold amount of lives and denied Al Qaeda the symbolic victory of "smashing the center of American government," Clinton said.

On Saturday, the president stopped at Arlington National Cemetery to visit graves of troops killed in Iraq and Afghanistan, the two long wars he inherited and is beginning to wind down.

The Associated Press contributed to this report.