During the 590s, Æthelfrith became the most powerful ruler in Northumbria. Following the battle of Degsastan in 603, he became sufficiently powerful to absorb Deira within his rule. In his second marriage Æthelfrith married Edwin's sister Acha. Hereric married Breguswith and had two daughters, Hereswith and her younger sister Hild (born around 613). Hereric was exiled and forced to seek protection in the British kingdom of Elmet, then ruled by Ceretic. During Hereric's exile, Edwin lived at the court of Cearl of Mercia, where he married Cearl's daughter and had two sons. Here he fell under the broader protection of the southern English kingdoms whose overlord was Aethelberht of Kent (ruled from about 560 to 616). During the latter part of Æthelberht's rule, power gravitated towards Rædwald of East Anglia, who had signalled his intention to succeed to the dominion of Æthelberht by receiving baptism in Kent from the Roman mission of Augustine of Canterbury.