Athelfrith ( 616), in 593 became King of Bernicia. In 604 he conquered Deira and became the first King of Northumbria. Aethelfrith was the first great leader among the Angles north of the River Humber. Bede called him an ambitious and powerful king who cruelly ravaged the Britons more than any other English leader. He was killed in battle against the East Angles.