The attack on 6 January 2021 intended to disrupt the peaceful transfer of power from Donald Trump to Joe Biden after the 2020 presidential election.

Joseph Biggs' sentence is the second longest among the numerous Capitol riot cases so far - only surpassed by the 18-year prison sentence handed to Oath Keepers founder Stewart Rhodes.

Federal prosecutors had initially recommended a 33-year prison sentence for Biggs since he played a prominent role in leading dozens of Proud Boys members and associates in their march to the Capitol.

Alongside other Proud Boys, Biggs joined the mob that breached police lines, causing legislators to flee and interrupting Congress' joint session to certify Mr Biden's electoral victory.

During his sentencing, Biggs expressed remorse and acknowledged his wrongdoing.

"I know that I messed up that day," he told the judge just before being sentenced, "but I'm not a terrorist".

The judge who sentenced Biggs will also be responsible for sentencing four other convicted Proud Boys.

They were found guilty by a jury in May after a four-month trial that exposed the far-right extremists' endorsement of baseless claims made by Mr Trump that the election was stolen from him.

Enrique Tarrio, the former national chairman and top leader of the Proud Boys, is set to be sentenced next week.

He was notably absent in Washington on 6 January as he had been arrested two days prior for allegedly defacing a Black Lives Matter banner during a previous rally.

Tarrio adhered to a judge's order to leave the city following his arrest and entrusted Biggs and Proud Boys chapter president Ethan Nordean to lead the group in his absence.

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Biggs, who hails from Ormond Beach, Florida, had identified himself as a Proud Boys organiser.

Prior to this, he had served in the US army for eight years before receiving a medical discharge in 2013.

He then worked as a correspondent for Infowars, a website operated by conspiracy theorist Alex Jones.

In addition to Biggs, Tarrio, Nordean, and Proud Boys chapter leader Zachary Rehl were convicted of seditious conspiracy charges, a rarely pursued offence in the US dating back to the country's Civil War era.

Another Proud Boys member, Dominic Pezzola, was acquitted of seditious conspiracy but faced other serious charges.

Prosecutors recommended sentences of 33 years for Tarrio, 30 years for Rehl, 27 years for Nordean, and 20 years for Pezzola.

Sentencing for Rehl is scheduled for later today, while Pezzola and Nordean are set to be sentenced on Friday.

Defence lawyers argued their clients were unjustly held accountable for the violent actions of other Trump supporters present at the Capitol.

More than 1,100 people have been charged with federal crimes related to the Capitol riots, with around 600 having already been convicted and sentenced.

Apart from Rhodes, six members of the anti-government Oath Keepers were also convicted of seditious conspiracy after a separate trial last year.