Donald Trump was described as the “inciter-in-chief” who “had left everyone in this Capitol for dead” as the impeachment trial against him began in earnest.

During eight hours of testimony, Democrat politicians, acting as “impeachment managers”, berated Mr Trump for having whipped up an atmosphere of such febrile aggression that a demonstration of support for him on 6 January was bound to degenerate into a violent confrontation.

But this day did not simply feature speeches, but also shocking images, not previously seen, of what happened when a mob attacked the Capitol building.

Please use Chrome browser for a more accessible video player

You Might Like

Some of the video evidence demonstrated the violence that swirled on that day – people throwing metal poles at police officers and rampaging through the heart of American politics.

And some of it was about the fear. We saw footage of Vice President Mike Pence, along with his family, being ushered away from a hiding place, with protestors just a hundred feet away.

There was Chuck Schumer, who leads the Democrat group in the Senate, being led by his security detail down one corridor, and then having to run back again as they saw the mob.

We see Mitt Romney, a Republican senator, running down a corridor in fear, Nancy Pelosi’s staff barricading themselves into an office, and congressmen and women being led down a back staircase, wearing gas masks.

There is the image of a mock gallows that has been erected just outside the Capitol, and shouted threats to kill Mr Pence and Mrs Pelosi. And security camera footage showing how people had smashed passed police barriers and broken windows to force their way into the building.

They are images that carry a particular resonance. Not just because they show a mob intimidating people, but that the people being intimidated include the very people now sitting in judgement on the former president.

“But for the grace of God, they would have got us – all of us,” said another impeachment manager, David Cicilline, a Democrat Congressman.

On their own, none of this means that Donald Trump is guilty of inciting an insurrection, as is alleged.

But this spectre is the mainstay of the narrative that is being constructed against him – that Mr Trump wantonly whipped up an atmosphere that was so furious and volatile that it would inevitably lead to the violence visited upon the Capitol on 6 January.

The message to Republican Senators appeared clear – that they are being asked to sit in judgment not on a politician from their own party, but on a person whose actions imperilled their own lives.

Subscribe to the Daily podcast on Apple Podcasts, Google Podcasts, Spotify, Spreaker

In fact, we now have a clear idea of how the Democrats have built their case against Mr Trump. They know that his lawyers will lean on the former president’s constitutional right to free speech as part of his defence, so they have tried to pre-empt that by investing time in trying to demonstrate that his actions were incendiary and reckless.

Famously, the First Amendment does not protect a person who “shouts ‘fire’ in a crowded theatre”.

But this case, claimed the lead impeachment manager, Jamie Raskin, was more dangerous.

“This case is much worse than someone who falsely shouts fire in a crowded theatre,” he said.

“It’s more like a case where the town fire chief, who’s paid to put out fires, sends a mob not to yell ‘fire’ in a crowded theatre, but to actually set the theatre on fire and who then, when the fire alarms go off, and the calls start flooding into the fire department, asking for help, does nothing but sit back, encourage the mob to continue its rampage and watch the fire spread on TV with glee and delight.”

They will press hard for Republicans to set aside partisan loyalty, to think of what is, according to their interpretation, the best way for the United States to heal.

Please use Chrome browser for a more accessible video player

In the minds of the Democrats, that is to convict Mr Trump and probably to then vote to bar him from again running for public office. But it will be hard to convince enough Republicans to follow that lead.

Six of them did break party ranks to vote to support this trial going ahead, but it would take at least 17 Republican senators to vote for conviction at the end of this trial and that remains unlikely.

The trial is likely to run through the weekend before finishing next week. Mr Trump is watching events from his home in Florida, and has yet to make any public comment.