Athelfrith was the son of Athelric of Bernicia and grandson of Ida of Bernicia. In 593 Athelfrith became King of Bernicia. According to Frank Stenton "The continuous history of Northumbria, and indeed of England, begins with the reign of Athelfrith..." Among the northern Angles, Aethelfrith was the first great leader. He gained more territory from the Britons than any other English leader.