Battle of Maserfield
The battle of Maserfield left Penda "the most formidable king in England." Following the battle, Deira, in the southern part of Northumbria, chose a king of its own, Oswine. Bernicia in the north was ruled by Oswald's brother Oswiu. The immediate effect of the battle was to weaken and divide Northumbria. The long term effect was that Oswiu restored Northumbrian power over the next 13 years. He finally defeated and killed Penda at the Battle of Winwaed in 655.