Several events led to the battle of the Winwaed. King Oswald of Northumbria was considered the or overlord over the other Anglo-Saxon kingdoms in England. Penda of Mercia defeated and killed Oswald of Northumbria in 642 at the battle of Maserfield. This left Penda the most powerful king in England. Penda did not claim to be the overlord, however. When his brother Oswald was killed, Oswiu of Northumbria claimed the throne of Bernicia but was not able to rule Deira. It was a year before Oswiu felt it was safe enough to recover his brother's body from the battlefield where he was killed. To appease Penda Oswiu gave his daughter in marriage to Penda's son Peada. Also Oswiu agreed to the marriage of his son Alfrith and Penda's daughter Cyneburh. Still, Penda was not satisfied. He was determined to destroy Oswiu. In 654 Penda raised a large army of some thirty 'legions'. Then, about 653, Penda began raiding into Bernicia.