Ceadda or Chad, the patron saint of Lichfield, carried Christianity to the Mercians.

Diuma preached to the Middle English of Leicester with much success, Peada, their ealdorman, son of Penda, having himself already embraced the new faith.

Penda had slain Oswald in a great battle at Maserfeld in 641; but the martyr only brought increased glory to the Christians: and Oswiu, who succeeded him, after an interval of anarchy, as king of Deira (for Bernicia now chose a king of its own), was also a zealous adherent of the Celtic missionaries.

Thus the heterodox Church made rapid strides throughout the whole of the north.
Meanwhile, in the south the Latin missionaries, urged to activity, perhaps, by the Pictish successes, had been making fresh progress.

In the very year when Oswald was chosen king by the Northumbrians, Birinus, a priest from northern Italy, went by command of the pope to the West Saxons: and after twelve months he was able to baptise their king, Cynegils, at his capital of Dorchester, on the Thames, his sponsor being Oswald of Northumbria.