Authorities said the plot by the men, who appeared motivated by Islamic extremism, failed only because they arrived too late and the rally by the English Defense League had already dispersed.
Judge Nicholas Hilliard of London's Central Criminal Court sentenced three of the men, Omar Khan, 31, Jewel Uddin, 27, and Zohaib Ahmed, 22, to a minimum of 19 and a half years for preparing acts of terrorism. The other three -- Mohammed Saud, 23, Anzal Hussain, 25, and Mohammed Hasseen, 23 -- received sentences of 18 years and nine months.
In all six cases, the judge reserved the right to later add an additional five years to the sentences.
The six were apprehended as the result of a chance encounter with traffic police checking on their expired car insurance as they returned to Birmingham from the northern town of Dewsbury, where the rally had been held. Inside the car, police found homemade nail bombs, a half-finished pipe bomb as well as shotguns, machetes and knives.
The car also contained extremist Islamic literature.
In summing up, Hilliard told the defendants: “You anticipated that some victims may have died. That must follow from the nature of the dreadful collection of material with which you were armed.” He added that the random nature of the attack meant those at risk would have included bystanders, including police officers monitoring the rally and innocent passers-by.
He described the anti-Western literature police found inside the car, which called for attacks on the British queen and prime minister and claiming their aggression was in retaliation for anti-Muslim insults from the English Defense League, named in the leaflets as the "English Drunkards' League."
"You should know that for every action there is a reaction," the documents said. "Today is a day of retaliation [especially] for your blasphemy of Allah and his messenger Muhammad. … We love death more than you love life. The penalty for blasphemy ... is death."
After the hearing, according to the BBC, EDL leader Tommy Robinson called out, "God save the queen," and the convicted men responded with a shout of "God is great" in Arabic.
The men all pleaded guilty last April to planning an attack on the rally and during the trial their defense lawyers claimed it was an "amateurish" attack not intended to cause fatalities.
West Midlands police said all six men were British citizens, although not all were British-born. They did not say where the immigrants were from.
Assistant Chief Constable Marcus Beale, speaking on air after the sentencing, said, "These six men planned a horrendous attack in Dewsbury, they probably would have killed people, they definitely would have caused lots and lots of injuries. … I'm delighted that they are properly housed within our jails, which is where they deserve to be."