 In 867 a force led by Cennétig mac Gaíthéne, king of Loígis, burned the fortress at Clondalkin and killed 100 of Amlaíb's followers.The monastery was later restored and, with help from other surrounding monasteries, influenced the Viking settlers in their conversion to Christianity.The district remained under Norse control until the Viking defeat by Brian Boru at the famous Battle of Clontarf in 1014.