Page "Osric of Deira" Paragraph 1

After Edwin was killed in battle against Cadwallon ap Cadfan of Gwynedd and Penda of Mercia, Northumbria fell into disarray, with Eanfrith taking power in the sub-kingdom of Bernicia and Osric taking power in Deira.

According to Bede, Osric was, like Eanfrith, a Christian who reverted to paganism upon coming to power.