The Omagh bombing was today described as a "massacre of the innocents" as a landmark civil action opened at the High Court in Belfast.
Twenty-nine people died, including a mother pregnant with twins, and hundreds more were injured when the Real IRA bombed the Tyrone town in Au gust 1998.
Some of those who lost loved ones and some of those who were injured launched the multi-million pound civil action following the failure of the authorities to bring anyone to justice for the bombing.
The court was told that terrorists will have to live in fear of losing all their assets if the case is successful.
The case, the first of its kind anywhere, is being brought by relatives of six people killed in the 1998 atrocity who are suing for physical and psychological damage.
Writs were served on five men, Michael McKevitt, Seamus Daly, Seamus McKenna, Liam Campbell and Colm Murphy, in July 2002. The families believe all five men were involved in the blast.
In his opening submission to the court, Lord Brennan QC, representing the families, said the Omagh bomb had been "the most infamous atrocity" in the history of Northern Ireland. He described it as "a massacre of in nocents" and said that, for the first time, victims of terrorism are suing the alleged perpetrators.
"If successful and damages are pursued, then the result will be that every terrorist will have to live in fear that their essential belongings - house, car - will be taken from them," Lord Brennan told the court.
He claimed in court that all five defendants were convicted terrorists who knew or knew of each other.
He said McKevitt, who is currently serving 20 years in Portlaoise Prison, was leader of the Real IRA at the time of the bombing. Campbell, it was claimed, was a senior Real IRA officer with responsibility for operations.
The court was told that Colm Murphy was allegedly a member of the Continuity IRA, while Seamus Daly and Seamus McKenna were said to be Real IRA foot soldiers.
Barristers acting for four of the defendants objected to Lord Brennan’s accusations. Only Liam Campbell does not have legal representation — a strategy which Lord Brennan said was "deliberate and considered".
"It is our case that the defendants have tried to stop us getting to trial," said Lord Brennan.
He argued that the Real IRA was a terrorist organisation "dedicated to armed conflict".
An argument that, by placing the 500lb car bomb on a busy street, those responsible were liable for the deaths and injuries sustained as a result of the explosion, received nods from victims’ families, including Victor Barker, who were packed into the courtroom.
Members of nine bomb victim families were named among the original 22 plaintiffs. However, a number have pulled out over the years.
Lord Brennan argued the reasons behind this were "understandable".
The court was packed to capacity with reporters from all over the world flown in for the case.
Three videolink screens were placed at the front of the court linking pro ceedings with Portlaoise Prison.
Filing cabinets filled with bulging lever-arch folders of evidence lined each side of the room.
Speaking before the case, Michael Gallagher, whose 21-year-old son Aiden ,died in the Omagh bombing, said the families were seeking "justice, not re venge".
Outside the court, Mr Gallagher said he hoped the civil action would bring some control back into their shattered lives.
He said: "It is enormously difficult for all the families to deal with, but we feel we have no choice. To coin a euphemism, we haven’t gone away, you know, and we won’t be going anywhere."
Today’s unprecedented legal action will be closely monitored by victims of terrorist violence across the world and Mr Gallagher said he thought it would bring hope to those watching.
In December last year, south Armagh man Sean Hoey was cleared of 29 counts of murder relating to the Omagh bomb.
During his lengthy trial, families were able to watch proceedings via video link. This time no arrangements have been made, meaning the families will have to make a 150-mile round trip to Belfast every day.
A high-powered legal team - headed by top London solicitor Jason McCue - has been hired with senior counsel Lord Brenan QC representing the Omagh families.