Oswald of Northumbria was a king who ruled over the Anglo-Saxon kingdom of Northumbria in the early 7th century. He is best known for his efforts to spread Christianity in his kingdom and for his role in uniting various tribes under his leadership. Oswald became king after defeating his rival, Cadwallon, in the Battle of Heavenfield in 634 AD. Oswald was a devout Christian and invited missionaries, including Aidan of Lindisfarne, to help convert his people. His reign is often seen as a time of peace and prosperity, and he is remembered as a saint in both the Catholic Church and the Anglican Communion.