Arthurs is one of six children, and the fourth of Paddy and Amelia Arthurs. He works on the family farm learning how to drive diggers. He works as an agricultural contractor for the farm. He has one young daughter.
Arthurs joins the East Tyrone Brigade of the Provisional IRA in 1982 in the wake of Martin Hurson‘s death on the 1981 Irish Hunger Strike. Hurson is also from Galbally like Arthurs, and Arthurs and his friends look up to Hurson. At the time he joins so do other young men from the same area, like Tony Gormley, Eugene Kelly, Seamus Donnelly and Martin McCaughey.
Over a year and a half year period in the mid-1980s the East Tyrone Brigade attacks and bombs Royal Ulster Constabulary (RUC) barracks and stations in Ballygawley, Tynan, The Birches, Coalisland, Dungannon, Carrickmore and Castlederg. They bomb hotels and other businesses in Kildress, Ballyronan, Dungannon and Cookstown.
Arthurs takes part in two of the IRA’s biggest attacks of the 1980s. At the attack on the Ballygawley barracks in December 1985 and the attack on the RUC Birches barracks in August 1986, Arthurs is a key member of the team who drives a digger past a security fence, stops it outside the barracks, lights a fuse, runs to safety and wrecks the barracks with a 200-pound bomb in the JCB Digger.
Arthurs is killed along with seven other IRA Volunteers who are ambushed by the Special Air Service (SAS) during the Loughgall Ambush on May 8, 1987. Before the SAS fires he lights the 40-second fuse on the bomb and it destroys most of the station, injuring a number of British decoys inside. The Loughgall ambush is supposed to be a carbon copy attack of the bombing of The Birches barracks, with the IRA expecting no resistance. One of the photos of the aftermath of the ambush shows that Arthurs died with the Zippo lighter he used to light the fuse still in his hand.
Amelia Arthurs, Declan’s mother, says of the ambush in an interview to journalist Peter Taylor, “He was mowed down. He could have been taken prisoner. They knew that the ‘boys’ were coming and they lay in wait. The SAS never gave them a chance. Declan died for his country and I’m very proud of him. He was caught up in a war and he died.”
Arthurs is buried in St. John’s Cemetery, Galbally, beside IRA Volunteer Seamus Donnelly who also died in the Loughgall ambush.