Ex-President Donald Trump aimed supporters at the US Capitol "like a loaded cannon", Democrats have said in a pre-trial brief filed by House impeachment managers.
Prosecutors from the House of Representatives submitted an 80-page memorandum on Tuesday documenting how the former US president called supporters to Washington and set them loose on the US Capitol.
They accused Trump of creating a "powder keg" of discontent among supporters who on 6 January became an "armed, angry, and dangerous" mob.
However, Trump's legal team, which submitted a 14-page document, have dismissed his impeachment as "unconstitutional" over the Capitol riots last month as he is no longer in office.
Trump is the first US president in history to be impeached twice, making this his second impeachment trial.
Watch ITV News Washington Correspondent Robert Moore's report from inside the US Capitol as protesters stormed the building
The storming of the Capitol occurred while Congress was meeting inside to certify the election victory of President Joe Biden.
Five people have died as a result of the assault on Congress, including a woman who was trying to get through the last line of defence and into the Chamber.
Nine Democrats from the House of Representatives - known as the impeachment managers - lodged a brief which counters arguments from Republicans that the proceedings should not go ahead.
Trump is charged with incitement of insurrection.
If convicted, Trump could be barred from political office, but it seems unlikely Democrats will find the 17 Republican votes they need.
Listen to our US election podcast - Robert Moore on reporting on the Capitol riots
Trump’s lawyers said: "It is denied that President Trump incited the crowd to engage in destructive behaviour.
"It is denied that the phrase, 'If you don’t fight like hell you’re not going to have a country anymore' had anything to do with the action at the Capitol, as it was clearly about the need to fight for election security in general, as evidenced by the recording of the speech," his legal team said.
But the House impeachment managers have said: "His conduct endangered the life of every single member of Congress, jeopardised the peaceful transition of power and line of succession, and compromised our national security."
They added Trump's supporters had arrived in Washington "prepared to do whatever it took to keep him in power."
"All they needed to hear was that their president needed them to 'fight like hell'. All they needed was for President Trump to strike a match," they added.
Trump's second impeachment trial is due to take place in the Senate from 9 February.