When a pro-Trump mob laid siege to the US Capitol on January 6, 2021, several people died and scores were injured, including some 140 police officers. Windows were smashed. Desks were overturned. Faeces were smeared on the Capitol’s walls.

But the attack wasn’t just a depraved and violent episode; it also required the evacuation of the Capitol, disrupting the confirmation of president-elect Joe Biden’s victory. It was an insurrection, part of a much broader and sustained assault on democracy, months in the making, which represents the most serious domestic threat to America since the Civil War.

In other words: it was an attempted coup. When the bipartisan House committee investigating the January 6 attack takes its proceedings to prime-time TV, it needs to hammer home this essential truth.

Democracy, not partisan politics, is what is at stake. An airing of what the committee has learnt will not interest or sway always-Trumpers who have displayed little interest in democracy anyhow. But a focused narrative that establishes how far-reaching the coup attempt was, and who led it, will remind Justice Department prosecutors of the work they still have to do — and challenge voters to stand up for democratic values.

There is already ample evidence of the sheer lawlessness of January 6. In March, federal District Judge David Carter said that former president Donald Trump likely and knowingly committed fraud when he and one of his lawyers, John Eastman, plotted to block Congress’s certification of the 2020 presidential election so Trump could remain in office. Carter called the effort a “coup in search of a legal theory”, and he approved releasing Eastman and Trump’s communications to the January 6 committee.

Eastman advised Trump to pressure then Vice-President Mike Pence not to certify the election on January 6, even though Eastman knew the manoeuvre was unlawful. Trump absorbed that advice so fully that when Pence refused to partake in a coup, the former president publicly berated him on Twitter. When the Capitol was stormed on January 6, the mob chanted for Pence to be hung.

On Tuesday, Carter ordered the release of more of Eastman’s communications with Trump and pro-Trump groups. This batch showed that Eastman was involved in meetings in early December — a month after the presidential election and a month before the siege — that Carter found particularly disturbing.

“Eastman’s actions in these few weeks indicate that his and President Trump’s pressure campaign to stop the electoral count did not end with Vice-President Pence — it targeted every tier of federal and state elected officials,” Carter noted. “Convincing state legislatures to certify competing electors was essential to stop the count and ensure President Trump’s re-election.”

Court documents also show that Trump and Eastman’s manoeuvres, fully baked in early December, were dubbed “the January 6 strategy” by the conspirators. One of them, unnamed in the documents, advised that they keep their scheme secret.

Eastman and other Trump advisers involved in the coup operated out of a set of rooms and suites a block away from the White House at the Willard Intercontinental Hotel that they nicknamed “the command centre”. Rudy Giuliani, Steve Bannon, Bernard Kerik and Boris Epshteyn were also members of the Willard’s brains trust.

Long before the January 6 siege, Giuliani was advising Trump directly and leading dozens of state-by-state legal challenges to the 2020 election results. Judges, Republican and Democratic alike, roundly tossed out the challenges — sometimes highlighting how ridiculous and ill-founded the lawsuits were.

There were also boots on the ground. Two militant pro-Trump groups, the Proud Boys and the Oath Keepers, staged protests about the 2020 election after Biden’s victory and showed up in force in Washington on January 6. Federal authorities have charged members of both groups with :seditious conspiracy“, a seldom-used Civil War-era law prosecutors deploy against individuals for undermining the legitimacy of the state. The January 6 hearings may offer a window into how directly Trump’s team worked with those groups.

More than 800 people have already been charged with crimes stemming from their actions on January 6, and 300 have pleaded guilty. About 200 have been sentenced, from a little as probation to five years in prison. But no one in the upper echelons of the White House has been charged with any crime other than ignoring subpoenas from the January 6 committee.

The most prominent member of this group, of course, is Trump himself.

He pursued the big lie that the 2020 election was a fraud even though his own advisers — including former Attorney-General William Barr — told him otherwise. He had practice, too. In the months before the 2016 presidential election, which he worried he might lose to Hillary Clinton, Trump rattled on that a loss would mean the whole thing was rigged.

Throughout his presidency, he revelled in calling for his supporters to engage in violence as a demonstration of their loyalty to him. He was disinclined to condemn political and racial violence when it surfaced. His longstanding embrace of violence and lawlessness came together in full force before January 6 and erupted at the Capitol.

The mob rallied in front of Trump on January 6, and he told them he loved them. They shouted back that they loved him, too — and then went on to storm the Capitol. Trump wasn’t a bystander that day, or in the days before and after. He was a ringleader. Advisers brought him ideas on how to effect a coup, and he signed off on them. Even if Trump didn’t directly lead some of the most disturbing events surrounding January 6, he inspired them.

The January 6 committee reportedly plans to have a theme for each of its hearings. That’s a good approach, and will help viewers to focus. But there’s one main theme that ties it all together: coup.

The threat to democracy that became so vivid on January 6 has not gone away. To that end, the January 6 committee's hearings are indispensable. Ideally, they will show what can happen when any political actor, but especially the president, thinks he or she is above the law. They will increase pressure on federal prosecutors to take stronger action. And the hearings might also challenge naysayers and the apathetic to realise that, sometimes, preserving democracy requires taking sides.

• Timothy L. O'Brien is a senior columnist for Bloomberg Opinion covering US business and politics. A former editor and reporter for The New York Times, he is author of TrumpNation: The Art of Being the Donald