 They also forged an alliance with the King of Osraige Cerball mac Dúnlainge, who was one of the most powerful and ambitious men in the country.In 856 a major conflict arose between the Norsemen and Máel Sechnaill, who was then allied to mercenaries of mixed Gaelic and Scandinavian background known as the Gallgoídil.In that year two important ecclesiastical settlements in Brega — Slane and Lusk — were sacked.