the southern English: the Chronicle later repeated this claim, referring to Ceawlin as a bretwalda, or "Britain-ruler". Ceawlin was deposed, perhaps by his nephew, Ceol, and died a year later. Six years later, in about 594, Ceol was succeeded by a brother, Ceolwulf, who was succeeded in his turn in about 617 by Cynegils. The genealogies do not agree on Cynegils' pedigree: his father is variously given as Ceola, Ceolwulf, Ceol, Cuthwine, Cutha or Cuthwulf. The tradition embodied in the Anglo-Saxon Chronicle, and in the genealogies of the West Saxon dynasty, is open to considerable doubt. This is largely because the founder of the dynasty and a number of his alleged descendants had Brittonic Celtic, rather than Anglo-Saxon Germanic, names. The name Cerdic is derived from the British name *Caraticos.Koch, J.T., (2006) Celtic Culture: A Historical Encyclopedia, ABC-CLIO, , pp. 394–395. This may indicate that Cerdic was a native Briton, and that his dynasty became anglicised over time.Yorke 1995, pp. 190–191 Other members of the dynasty possessing Celtic names include Ceawlin and Cædwalla. Cædwalla, who died as late as 689, was the last West Saxon king to possess a Celtic name. Christian Wessex and the rise of Mercia It is in Cynegils' reign that the first event in West Saxon history that can be dated with reasonable certainty occurs: the baptism of Cynegils by Birinus, which happened at the end of the 630s, perhaps in 640. Birinus was then established as bishop of the West Saxons, with his seat at Dorchester-on-Thames. This was the first conversion to Christianity by a West Saxon king, but it was not accompanied by the immediate conversion of all the West Saxons: Cynegils' successor (and probably his son), Cenwealh, who came to the throne in about 642, was a pagan at his accession. However, he too was baptised only a few years later and Wessex became firmly established as a Christian kingdom. Cynegils's godfather was King Oswald of Northumbria and his conversion may have been connected with an alliance against King Penda of Mercia, who had previously attacked Wessex. These attacks marked the beginning of sustained pressure from the expanding kingdom of Mercia. In time this would deprive Wessex of its territories north of the Thames and the (Bristol) Avon, encouraging the kingdom's reorientation southwards. Cenwealh married Penda's daughter, and when he repudiated her, Penda again invaded and drove him into exile for some time,