In 654 Anna was slain by Penda of Mercia, and was succeeded by his brother 2Ethelhere, who was killed in 655 at the Winwaed, fighting for the Mercian king against Oswio of Northumbria.
After Oswio's victory over Penda in 654-655 he annexed the northern part of Mercia to his kingdom and acquired a supremacy over the rest of England similar to that held by his predecessors.
In 642, however, Oswald was slain by Penda in a battle at a place called Maserfeld, which has not been identified with certainty.
Shortly afterwards both brothers were slain by Penda of Mercia in his invasion of East Anglia, and Anna became king.
The church that they founded struck root, as that of Paulinus and Edwin had failed to do, and was not wrecked even by Oswalds deatn in battle at the hands of Penda the Mercian, the one strong champion of heathenism that England produced.
In 642 Penda slew Oswald at a place called Maerfeld.
During the reign of Oswald Penda clearly reigned under the suzerainty of that king.
After Oswald's defeat and death at the hands of Penda in 642 Bernicia fell to his brother Oswio, while Oswine son of Osric became king in Deira, though probably subject to Oswio.