WATCH: Senators mark Jan. 6 attack anniversary

To mark the first anniversary of the U.S. Capitol attack, Senate Majority Leader Chuck Schumer told the chamber Thursday, “The warnings of history are clear: when democracies are in danger, it often starts with a mob.”

Watch senators address the chamber in the player above.

“And for mob violence to win the day, it doesn’t need everyone to join in. It just needs a critical mass of people to stay out of the way – to ignore it, to underestimate it, to excuse it, and even condone it.”

Schumer led an array of senators making floor remarks to colleagues in floor speeches recalling the insurgency and the threat the Capitol attackers put on American democracy that day.

The president of the United States called out predecessor Donald Trump not by name but by reputation Thursday, marking one year since the Capitol Hill riots with a remarkably simple exhortation to his fellow Americans: to tell and spread and embrace the truth about the 2020 election.

READ MORE: How Americans describe Jan. 6, one year later

At a podium in Statuary Hall in the heart of the Capitol, Joe Biden acknowledged behind him the archway statue of Clio, the muse of history, whose stenographic pose depicts her documenting the proceedings of the House of Representatives, which met in the hall in the half-century before the Civil War.

Clio also bore witness to what happened a year ago, Biden said – “the real history, the real facts, the real truth” – as a violent, angry mob stormed through the building, attacking police officers and menacing lawmakers, fueled not by a belief in democracy but by a misguided attempt to subvert it.

The riot – Biden himself called it an “armed insurrection” – erupted after thousands of Trump supporters, fresh from the angry rhetoric of a speech from the man himself in the shadow of the Washington Monument, flooded the Capitol grounds on the very day Congress was to certify the election results.

Factions of them pushed past a meagre and overmatched security perimeter and stormed the building, Trump flags and Confederate symbols on full display as they attacked Capitol Police officers, smashed windows and hammered on barricaded doors, some with terrified staffers cowering on the other side.

Outside, hordes of angry protesters, some wielding flagpoles still adorned with American flags as clubs and spears, turned their rage to the police officers trying to turn them back. Inside, chants of “Hang Mike Pence” could be heard as rioters, believing the vice-president to have betrayed their leader, sought out the man whose responsibility that day was to certify Biden’s victory. A makeshift gallows awaited outside.

With lawmakers, including Pence, having been spirited away to safety just moments earlier, many of the rioters – some equipped with handcuffs and ziptie restraints – found their way to the very chambers where on Thursday, members of Congress publicly remembered the day and paid tribute to the law enforcement officers who protected them.

WATCH: Jan. 6 insurrection ‘came very close,’ to being much worse, Rep. Jeffries says

Five people died either in or as a direct result of last year’s hours-long melee on Capitol Hill, including Capitol Police officer Brian Sicknick, who succumbed to his injuries the following day after being struck in the head with a fire extinguisher and hit in the face with pepper spray.

Protester and Air Force veteran Ashli Babbitt was shot and killed by police as she and several others tried to smash their way through the doors leading to the speaker’s lobby. Three other Trump supporters – Kevin Gleeson, Rosanne Boyland and Benjamin Philips – also lost their lives.

Trump, for his part, had been planning a news conference from the confines of his country-club compound in Florida, but cancelled at the last minute, opting instead to air his grievances during one of his trademark rallies next week in Arizona.

His reluctance to publicly urge rioters to retreat from the Capitol and go home, despite the now-public pleas to do so from some of his closest advisers and confidantes, has become the central focus of a special Senate committee that is examining the events of that day and what led up to it.