Six men from the West Midlands have pleaded guilty to planning to bomb an English Defence League rally.
Omar Mohammed Khan, Mohammed Hasseen, Anzal Hussain, Mohammed Saud, Zohaib Ahmed and Jewel Uddin admitted preparing an act of terrorism. All six will be sentenced on 6 June.
Five of them took a homemade bomb to an EDL rally in Dewsbury, West Yorkshire, last June but arrived after it ended.
They were caught after their car was stopped and found to have no insurance.
Police and security services had no intelligence about the planned attack, although one of the would-be killers, Jewel Uddin, was under surveillance in relation to another terror plan.
After the hearing at Woolwich Crown Court, Assistant Chief Constable of West Midlands Police Marcus Beale said: "Their capability was clear.
"They created devices that would have certainly maimed and possibly killed people depending on how close they were.
"Their intent was very, very clear. In my view they were very dangerous."
Tommy Robinson, aka Stephen Lennon, leader of the EDL, said he welcomed the convictions.
On 30 June 2012, the EDL, an anti-Islamic group that says it supports peaceful protest, held a rally in Dewsbury, despite attempts by the Muslim community in the town to have it stopped.
Police estimated there could have been as many as 750 EDL supporters in attendance, as well as dozens of police officers and passers-by.
As the rally was taking place, the five men travelled there in two cars, one of which was carrying a homemade bomb constructed out of a modified firework and containing 359 nails and 93 ball bearings.
They also had two sawn-off shot guns, parts of other explosive devices, knives and a long printed message, dated the same day, describing their motivation and calling the Queen a "female devil".
It said: "To the EDL (English Drunkards League). O enemies of Allah! We have heard and seen you openly insulting the final Messenger of Allah... you should know that for every action there is a reaction.
"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 of Allah and his Messenger Muhammad is death."
However, the men arrived after the EDL rally had broken up because the right-wing group had insufficient speakers to carry on later into the afternoon.
The would-be attackers left the town but were stopped by a traffic police officer on the M1 motorway for having no car insurance.
Days later, when the impounded vehicle was searched, the weapons were found - sparking a manhunt across Birmingham.
Following their arrests, it emerged that Uddin was already known to the police and MI5.
He was an associate of another group of Islamist terrorists, also based in Birmingham, who were jailed last week for planning an attack to rival the 7 July and 9/11 atrocities.
Uddin was under partial counter-terrorism surveillance, and five days before the aborted EDL attack, a West Midlands surveillance officer watched him and another man go to a homewares shop near his home in the Sparkhill area of Birmingham.
Police later established that the man accompanying Uddin was fellow plotter Omar Khan - and that the pair had bought some of the knives eventually found in the car boot.
A second member of the group, Ahmed, had been separately charged with possession of jihadist magazines that included bomb-making instructions. He was on bail at the time of the failed bombing.
Responding to suggestions police could have arrested Uddin earlier, ACC Beale said: "We didn't fail to join the dots.
"We were doing what was right and proportionate at the time."
Five of the men were from Birmingham - Uddin, 27, and Khan, 28, both from Sparkhill, Ahmed, 22 from Saltley, Hasseen, 23 from Tyseley, and Hussain, 24, from Moseley - and one, Saud, 22, was from Smethwick.
All changed their pleas from not guilty on Tuesday via videolink, admitting preparing an act of terrorism between 1 May and 4 July 2012.
Mr Robinson told the BBC he believed the plot was targeted at him personally.
The EDL leader said he had intended to travel to Dewsbury to be part of the rally but had been unable to go at the last minute for family reasons.
A statement from the Birmingham Coalition of Muslim Organisations and Mosques, which says it represents most of the city's 230,000 Muslims, said: "The Muslim community in Birmingham wishes to make one thing absolutely clear: These acts are not carried out in our name."