The mainstream UDA has been shaken to the core by the murder of one of its most senior commanders, writes Suzanne Breen.
"This shouldn't be happening," said a senior UDA figure in Belfast as the paramilitary group made plans last night for the funeral of one of its leading brigadiers.
Just hours before his death, John "Grug" Gregg was talking tough.
He had told a Belfast newspaper that Johnny Adair's Shankill Road C company had a fortnight to settle its feud with the mainstream organisation or face the consequences.
Gregg and the four other members of the Ulster Defence Association's ruling body, the inner council, had reason to be confident. When the British government returned Adair to prison last month for allegedly breaking the terms of his early release, the mainstream UDA believed C company would be emasculated without its leader.
Some mainstream UDA members, celebrating the apparent end of the feud by holidaying in Dubai, are alleged to have sent Adair a postcard.
Retrospectively, senior UDA members admit Gregg's security was lax. It is believed Adair supporters, who were also travelling back on the same ferry from the Rangers match in Scotland, telephoned C company to report his movements.
"John Gregg's travel arrangements were inadequate," one figure admitted. "He should never have been picked up from the boat in a vehicle without cover [armed protection\]."
The source said retaliation was inevitable.
"Action has to be taken. An organisation like the UDA will not stand by while its brigadiers are murdered. We will not let C company make fools of us. These people will be hunted down and eradicated like the vermin they are. They would be stupid to celebrate this murder.
"We are mourning now but there will be plenty more funerals and then we will have something to celebrate."
Another source said not to expect speedy retaliation. "The UDA will not go at this gung-ho. We will sit down and carefully consider what to do, but it will be done, however long it takes."
Gregg had already been targeted twice by Adair supporters. A booby-trap bomb was placed under his car and a pipe-bomb left outside his home in Rathcoole. Adair is said to have hated Gregg more than any of the five inner council members who expelled him and his associate, John White, from the UDA last autumn.
Saturday's double murder brings the death toll since those expulsions to four. Adair supporters shot dead Jonathan Stewart (22) in December and the UDA leadership killed Roy Green (32) last month.
The feud has no political roots. Apart from personality clashes, it centres on allegations of drug-dealing and racketeering by both sides. It also involves Adair's close relationship with the rival Loyalist Volunteer Force.
UDA sources said a non-aggression pact was reached with C company last week but was called off hours before the double murder after Adair intervened from jail.
A loud, forceful figure, Gregg played the bass drum in the Cloughfern Young Conquerors loyalist band and was once involved in trouble with nationalists at the Apprentice Boys' parade in Derry.
He was one of the UDA's representatives in its meetings with Gen John de Chastelain's decommissioning body.
He became a hero among loyalists after he tried to kill Gerry Adams in 1984.
He served nine years in prison. Interviewed in the Maze in 1990, he was asked if he had any regrets about the murder attempt. "Only that I didn't succeed," he replied.
While Adair's murderous campaign against the nationalist community is well known, Gregg should not be portrayed as some sort of peace-maker.
His south-east Antrim brigade, one of the UDA's most active, was responsible for a vicious pipe-bomb campaign against Catholic families in Larne and for several horrific murders.
Last year the brigade shot dead Catholic postman Daniel McColgan as he walked to work in Rathcoole. In 2001, it killed Protestant schoolboy Gavin Brett, mistaken for a Catholic, in Newtownabbey.
It also beat to death another Protestant, Trevor Lowry, in Glengormley after he too was mistaken for a Catholic.
The previous year, Gregg's men shot dead Catholic labourer Gary Moore in Monkstown. Security sources said the south-east Antrim commander was motivated by "pure sectarian hatred".
They said he had been responsible for "violence and intimidation against hundreds of Catholics" in his area.
Gregg's terror was even practised on his own members. He was reported to have ordered two gun attacks on the home of one UDA member who had spoken out against his involvement in drug dealing.