The Cross at Heavenfield
On returning from exile to claim his kingdom, Oswald faced the British king Cadwallon, whose forces were the stronger. According to the tradition reported by the sources, before the engagement Oswald had a wooden cross set up, holding it in place himself while earth was packed into the hole to secure it, and then summoned his army to kneel and pray to the one true God for deliverance. The site of the battle, fought around 634, is remembered as Heavenfield. Oswald's victory there both secured his throne and was understood as a vindication of the faith he professed.
Having won his kingdom, Oswald did not turn to the Roman clergy established at Canterbury but instead sent to Iona for missionaries to preach to his subjects. The monk Aidan was sent in response, and Oswald granted him the island of Lindisfarne, off the Northumbrian coast, where Aidan founded a monastery ordered on the pattern of the Celtic communities. The sources relate that the king accompanied Aidan on his missionary journeys and, knowing the Gaelic tongue from his years in exile, translated the bishop's preaching for the people.