 In the same year, Amlaíb plundered the great monastic settlement of Armagh.This raid was possibly launched in retaliation for the death of his son Carlus, who had lost his life the previous year fighting for the kings of Leinster and Brega against Áed Findliath (the protector of Armagh) in the Battle of Cella Ua nDaigri (Killineer, County Louth).We are not told when precisely the alliance between Amlaíb and Áed Findliath (established around 860) fell apart; possibly it happened when Áed became High King in 862.