Even by the standards of the Trump White House, a meeting on Dec. 18, 2020, that was highlighted Tuesday by the Jan. 6 committee was extreme.In taped interviews, witnesses described a meeting in which President Donald J. Trump’s outside advisers proposed an executive order to have the military seize voting machines in crucial states Mr. Trump had lost.Stefani Reynolds for The New York TimesThe meeting lasted for more than six hours, past midnight, and devolved into shouting that could be heard outside the room. Participants hurled insults and nearly came to blows. Some people left in tears.Even by the standards of the Trump White House, where people screamed at one another and President Donald J. Trump screamed at them, the Dec. 18, 2020, meeting became known as an “unhinged” event — and an inflection point in Mr. Trump’s desperate efforts to remain in power after he had lost the election.Details of the meeting have been reported before, including by The New York Times and Axios, but at a public hearing on Tuesday of the Jan. 6 committee, participants in the mayhem offered a series of jolting new details of the meeting between Mr. Trump and rival factions of advisers.“It got to the point where the screaming was completely, completely out there,” Eric Herschmann, a White House lawyer, told the committee in videotaped testimony. “I mean, you got people walking in — it was late at night, it had been a long day. And what they were proposing, I thought was nuts.”The proposal, to have the president direct the secretary of defense to seize voting machines to examine for fraud and also to appoint a special counsel to potentially charge people with crimes, had been hatched by three outside advisers: Sidney Powell, a former lawyer for Mr. Trump’s campaign who promoted conspiracy theories about a Venezuelan plot to rig the voting machines; Michael T. Flynn, the national security adviser Mr. Trump fired in his first weeks in office; and Patrick Byrne, the former chief executive of Overstock.com.On the other side were Pat A. Cipollone, the White House counsel; Mr. Herschmann; and Derek Lyons, the White House staff secretary.The arguing began soon after Ms. Powell and her two companions were let into the White House by a junior aide and wandered to the Oval Office without an appointment.They were there alone with Mr. Trump for about 15 minutes before other officials were alerted to their presence. Mr. Cipollone recounted receiving an urgent call from a staff member to get to the Oval Office.“I opened the door and I walked in. I saw General Flynn,” he said in a videotaped interview the committee played at the hearing on Tuesday. “I saw Sidney Powell sitting there. I was not happy to see the people who were in the Oval Office.”Asked to explain why, Mr. Cipollone said, “First of all, the Overstock person, I’ve never met, I never knew who this guy was.” The first thing he did, Mr. Cipollone said, was say to Mr. Byrne, “Who are you?” “And he told me,” Mr. Cipollone said. “I don’t think any of these people were providing the president with good advice.”Mr. Lyons and Mr. Herschmann joined the group. “It was not a casual meeting,” Mr. Lyons told the committee in videotaped testimony. “At times, there were people shouting at each other, hurling insults at each other. It wasn’t just sort of people sitting around on a couch like chitchatting.”Sidney Powell’s videotaped testimony, in which she said White House advisers had “contempt and disdain for the president,” was shown during Tuesday’s hearing.Doug Mills/The New York TimesMs. Powell, in her videotaped interview, described Mr. Trump as “very interested in hearing” what she and her two cohorts had to say, things that “apparently nobody else had bothered to inform him of.”Mr. Herschmann said he was flabbergasted by what he was hearing.“And I was asking, like, are you claiming the Democrats were working with Hugo Chavez, Venezuelans and whomever else? And at one point, General Flynn took out a diagram that supposedly showed IP addresses all over the world and who was communicating with whom via the machines. And some comment about, like, Nest thermostats being hooked up to the internet.”When the White House officials pointed out to Ms. Powell that she had lost dozens of lawsuits challenging the results of the 2020 election, she replied, “Well, the judges are corrupt.”“I’m like, everyone?” Mr. Herschmann testified. “Every single case that you’ve done in the country that you guys lost? Every one of them is corrupt? Even the ones we appointed?”Ms. Powell testified that Mr. Trump’s White House advisers “showed nothing but contempt and disdain for the president.”The plan, the White House advisers learned, was for Ms. Powell to become the special counsel. This did not go over well.“I don’t think Sidney Powell would say that I thought it was a good idea to appoint her special counsel,” Mr. Cipollone testified. “I didn’t think she should be appointed anything.”Mr. Cipollone also testified that he was alarmed by the insistence of Ms. Powell and the others that there had been election fraud when there was no evidence. “When other people kept suggesting that there was, the answer is, what is it? At some point, you have to put up or shut up. That was my view.”Mr. Herschmann described a particularly intense moment. “Flynn screamed at me that I was a quitter and everything, kept on standing up and standing around and screaming at me. At a certain point, I had it with him, so I yelled back, ‘Either come over or sit your f-ing ass back down.’”Cassidy Hutchinson, a top aide to Mark Meadows, the White House chief of staff, could hear the shouting from outside the Oval Office. She texted a deputy chief of staff, Anthony M. Ornato, that the West Wing was “UNHINGED.”After the meeting had started, Rudolph W. Giuliani, Mr. Trump’s personal lawyer, was called in by the White House advisers to argue against Ms. Powell. Eventually the meeting migrated to the Roosevelt Room and the Cabinet Room, where Mr. Giuliani found himself alone at one point, something he told the committee he found “kind of cool.”Finally, the group ended up in the White House residence.Ms. Powell believed that she had been appointed special counsel, something that Mr. Trump declared he wanted, including that she should have a security clearance, which other aides opposed. She testified that others said that even if that happened, they would ignore her. She said she would have “fired” them on the spot for such insubordination.Mr. Trump, she said, told her something to the effect of: “You see what I deal with? I deal with this all the time.”Eventually Mr. Trump backed down and rejected the outside advisers’ proposal. But early the next morning, Dec. 19, he posted to Twitter urging his supporters to arrive at the Capitol on Jan. 6, the day that a joint session of Congress was set to certify the Electoral College results.“Be there, will be wild!” he wrote. More