Oswald claimed the crowns of both Bernicia and Deira. By doing this he reunited Northumbria to a single kingdom. Oswald was the first king of Northumbria to come to the throne already a Christian. As one of his first acts Oswald set up what would become the holy island of . He asked for a bishop to come to Northumbria to convert his people to the Christian faith. They sent Bishop Aidan. Aidan built a monastery and created a Christian colony on the island of Lindisfarne off the coast of Bamburgh. Oswald, at least at first, had to translate for Aidan who did not speak English fluently. Oswald was considered a "" by Bede, the fourth such overlord over the other Anglo-Saxon kings. In 635, Oswald married Cyneburh, the daughter of King Cynegils of Wessex. Oswald also became the godfather of Cynegils when he was baptized . Oswald created several similar alliances in an effort to contain Penda of Mercia. About 638 he won a battle against Owen Map Bili, the king of Strathclyde near Edinburgh. In 640 Oswald tried to recover Lindsey from Penda. The two armies met again in 642 at the Battle of Maserfield (probably in Shropshire). Oswald was killed in the battle. For a year after the battle his head and hands were fastened to stakes. His brother Oswiu finally recovered Oswald's relics. Oswiu succeeded Oswald as king of Northumbria.