Brogan Stewart was sentenced to 11 years in prison, Christopher Ringrose for 10 years and Marco Pitzettu for eight years by a judge at Sheffield Crown Court on Friday.
Stewart, 25, Ringrose, 34, and Pitzettu, 25, stockpiled body armour and more than 200 weapons including crossbows, swords, machetes, axes, hunting knives and had 3D-printed parts of a gun.
An almost completed FGC-9 Mk II printed assault rifle found in Ringrose's loft was missing the barrel and firing pin, but the men were sourcing the components to complete the weapon, which prosecutors said could then "have been used to devastating consequences".
The court heard the trio had a shared interest in bushcraft and YouTube videos of "preppers" - who prepare for the possibility of a world-changing disaster by stockpiling supplies, food and ammunition.
But prosecutors said they were preparing for a race war and had used the online communities to recruit an inner circle, which moved on to neo-Nazi chat groups before setting up their own private group, as they prepared to take action.
It was infiltrated by an undercover officer on 5 January last year.
Stewart messaged the officer on the encrypted Telegram app, telling him he was disillusioned with other far-right groups that just "sit around and talk," adding: "I want to get my own group together because action speaks louder than words."
Self-appointed leader Stewart, of Tingley, Wakefield, West Yorkshire, appointed Ringrose, of Cannock, Staffordshire, and Pitzettu, of Mickleover, Derbyshire, as "armourers" and they discussed getting a uniform as well as potential targets, including mosques and synagogues.
In a group call on 5 February last year, they said the plan was to "cruise around" looking for "human targets" near an Islamic education centre, "do whatever we do, then back at mine for tea and medals and a debrief".
Before the "operation" went ahead, he wanted the members, who had never met in person, to "hang out, bring ourselves closer together and just cement that brotherhood" on 18 February.
But the event did not go ahead, and the group were arrested on 20 February after counter-terrorism police raided properties in Yorkshire, Derbyshire and Staffordshire.
All three men were found guilty of preparing acts of terrorism and possessing information useful for terrorism in May.
At trial, a jury ignored defence arguments that the defendants were fantasists with no intention of carrying out their threats.
Ringrose was also convicted of manufacturing the lower receiver for a 3D firearm, a prohibited weapon, while Pitzettu pleaded guilty to possessing a stun gun.
Jurors heard how the defendants formed an online group called Einsatz 14 in January 2024, with "like-minded extremists" who wanted to "go to war for their chosen cause".
Stewart told the group: "Hitler did more for his people than any politician. And for Britain to have a p*** and zionist in charge of the country is absolutely outrageous."
Prosecutors said this last comment was a reference to the then Prime Minister Rishi Sunak.
Sentencing them, judge Mrs Justice Cutts said she thought they all continued to believe in their extreme right-wing ideology.
All would be dangerous after their release from prison, she said, noting the group's ideology was "laid bare" in a 374-page dossier of internet activity presented to jurors.
The document was "filled with hate towards black and other non-white races, especially Muslim people and immigrants, with ideas of white supremacy and racial purity together with a belief that there must soon be a race war".
It featured the "glorification and admiration of the policies and actions of Hitler and the German Nazi Party, including antisemitism, and of mass killers who had targeted black or Muslim communities".
The judge said she did not believe a terrorist attack was "imminent", but "was likely in the not too distant future".
Detective Chief Superintendent James Dunkerley, head of Counter Terrorism Policing North East, said the group came together because of their "extreme racist views".
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"They've idolised the Nazi party, they've glorified mass murders, and they share a hatred of groups such as the Jewish community and the Muslim community," he said.
"I genuinely believe had we not taken action, this group could've carried out a violent attack and the consequences of that attack could've been fatal."