From Patrick Downes, who lost a leg when a pair of homemade bombs ripped through the crowds at the race's finish line, to Biden, speakers recalled how people on the scene, from police officers to spectators, reacted immediately to help the wounded amid a chaotic scene.
Former Boston Mayor Thomas Menino, who managed the response to the April 15, 2013, attack in the final year of his two decades in office, recalled the struggles of the families of Martin Richard, 8, Krystle Campbell, 29, and Chinese national Lu Lingzi, 23, who died in the blasts.
"You have struggled to get through the good days and the bad," said Menino, who had been hospitalized at the time of the blasts but responded to the scene against his doctor's orders. "I know because so many of you have told me about this year of firsts. First birthday without your beloved son, first holiday without your daughter, first July 4 where the fireworks scared you."
Downes, who had been standing near the finish line with his wife when the bombs went off, causing each to lose a leg, told the crowd of about 2,5000 people that he had been impressed by the city's outpouring of support for the wounded.
"We would never wish the devastation and pain we have experienced on any of you," Downes said. "However, we do wish that all of you, at some point in your lives, feel as loved as we have every day of this past year."
'NEVER ... YIELDED TO FEAR'
Federal prosecutors contend that a pair of ethnic Chechen brothers placed the pressure-cooker bombs at the race's crowded finish line and three days later shot dead a police officer in an unsuccessful attempt to steal his gun.
Biden, who had also spoke at a memorial service for the slain officer in the early aftermath of the attacks, sounded a note of defiance in his remarks, saying events like those at the marathon or the 2001 destruction of New York's World Trade Center and attack on the Pentagon demonstrate the resolve of average Americans.
"We refuse to bend, refuse to change, refuse to yield to fear," Biden said. "That is what makes us so proud of this city and this state, what makes me be so proud to be an American. It's that we have never, ever yielded to fear. Never."
At Tuesday's formal ceremony, which also featured performances by the Boston Pops and a youth choir, Roxbury Presbyterian Church Rev. Liz Walker summoned the memory of all four of the slain.
"Today we remember Krystle Campbell, her energy and zest, her adventure and passion, a generosity of spirit, a light that will never fade," Walker said. "We remember Lingzi Lu, heart and sparking eyes, music and guilelessness, a welcome smile that beams forever. ... We remember Martin Richard, tough and competitive, kind and caring, a Dorchester kid through and through. And we will remember Sean Collier, dedicated, with honor, trusted and respected."
Before the ceremony, Mayor Martin Walsh and Roman Catholic Cardinal Sean O'Malley, accompanied by the families of the three killed in the bombing, began the day on a quiet note, visiting wreathes lain at the spots on Boylston Street where the bombs went off.
They embraced and spoke softly as bagpipes played.
After the memorial, Boston will observe a moment of silence at 2:49 p.m. EDT (1849 GMT), the time the first bomb went off.
This year's Boston Marathon, set for April 21, will take place under heightened security, with the 36,000 runners and tens of thousands of expected spectators facing new restrictions, including bans on carrying backpacks into the race corridor.
Authorities say the ethnic Chechen brothers, Dzhokhar and Tamerlan Tsarnaev, carried their bombs to the finish line in backpacks.
Three days after the attack, the FBI released pictures of the suspected bombers and asked for the public's help in finding them. That prompted the Tsarnaev brothers to attempt a hasty flight from Boston, which began with them shooting Massachusetts Institute of Technology police officer Sean Collier, prosecutors said, in an unsuccessful attempt to steal his gun.
The resulting police chase ended in a gun battle in the Boston suburb of Watertown. Tamerlan, 26, was killed; Dzhokhar, now 20, escaped before being captured on April 19.
The surviving brother is awaiting trial on charges that carry the possibility of execution if he is convicted.