Two members of the far-right Proud Boys militia group who took part in the January 6, 2021 attack on the US Capitol with the intention of keeping Donald Trump in the White House were sentenced to lengthy prison terms on Friday.

Ethan Nordean, described by prosecutors as a leader of the extremist group, received an 18-year sentence for crimes that included seditious conspiracy, committed when thousands of Trump supporters overran the Capitol building.

Dominic Pezzola, who attacked a police officer and was filmed using the officer’s shield to smash a window, got 10 years from the federal judge Timothy Kelly in Washington DC, following his conviction in May for assault and obstructing an official proceeding.

Prosecutors had sought terms of 27 and 20 years, respectively, for Nordean and Pezzola.

The pair, described by prosecutors as “foot soldiers of the right [who] aimed to keep their leader in power”, were part of a mob seeking to disrupt the certification by a joint session of Congress of Democrat Joe Biden’s victory in the 2020 presidential election. Nine deaths have been linked to the riot, including law enforcement suicides.

Kelly reportedly told Nordean that he wished there was an “alternative history” where he did something other than lead the Proud Boys, complimenting him as a smart and articulate man. Nordean – of Auburn, Washington – said: “I would like to apologize for my lack of leadership that day,” according to Jordan Fischer of the WUSA television news outlet.

Sentencing Pezzola, Kelly said: “You were the one who smashed that window and let people begin to stream into that Capitol building and threaten the lives of our lawmakers. It’s not something I would have ever dreamed I would have seen in our country.”

Pezzola told the court he was “a changed and humbled man”, his “sorrow and regret … unimaginable”.

After Kelly left the courtroom and as US marshals led him away, Pezzola smiled, raised his hand and shouted: “Trump won,” according to a report from local news station WUSA.

His sentence was among the lengthiest handed down to those convicted of offences linked to the Capitol attack, in which 140 police officers were injured.

Pezzola, of Rochester, New York, posted to social media a profanity-laced video of himself inside the Capitol, smoking a cigar.

On Thursday, Judge Kelly sentenced the former Proud Boys organizer Joseph Biggs, a former US army captain, to 17 years behind bars, and handed a 15-year sentence to Zachary Rehl, another leader.

Like Nordean, both were convicted of seditious conspiracy, a civil war-era offense that is rarely brought. The sentences were the second- and third-longest stemming from the attack.

Two other members of the group, including its former leader Enrique Tarrio, are scheduled to be sentenced next week, with prosecutors calling for a 33-year sentence.

More than 1,100 people have been charged with federal crimes for their involvement in the riot and more than 600 have been convicted and sentenced. The most severe prison term yet given to a January 6 rioter, 18 years, was to the founder of the far-right Oath Keepers, Stewart Rhodes, in May, also for seditious conspiracy.

In their original filing to the court, prosecutors claimed Pezzola and Nordean were “trusted lieutenants” of Tarrio, his “boots on the ground” on the day of the attack.

“They unleashed a force on the Capitol that was calculated to exert their political will on elected officials by force and to undo the results of a democratic election,” they wrote. “The foot soldiers of the right aimed to keep their leader in power. They failed. They are not heroes; they are criminals.”

Trump lost the 2020 election by more than 7m votes and conclusively in the electoral college but falsely claimed the election was stolen. Currently the leading candidate for the Republican nomination in 2024, he faces 17 federal and state criminal charges arising from his attempt to cling onto power. Trump also faces 74 criminal charges on other matters.

They include allegations he incited the 6 January riot by summoning his extremist supporters to a rally at the Capitol in a tweet that read: “Be there, will be wild”.

On Thursday, Rehl, a former US marine, sobbed as his sentence was handed down. He told Kelly: “For what it’s worth, I stand here today and say that I am done with all of it. I am done with politics; I am done peddling lies for other people who don’t care about me.”

Norman Pattis, attorney for Rehl and Biggs, blamed Trump for the plight of his clients, whom he said were “given good reason by the highest official in the land” to question the legitimacy of Biden’s victory.

“What they’re guilty of is believing the president who said the election was stolen from him,” he said.