Œthelwald in 655 assists Penda during his…

Œthelwald in 655 assists Penda during his invasion of Northumbria.

However, when the armies of Oswiu and Penda meet at Cock Beck, near what later will be Leeds, on November 15 at the Battle of the Winwaed, Œthelwald withdraws his forces, as does Cadafael Cadomedd of Gwynedd.

Penda is defeated and killed, perhaps in part because of this desertion, and afterward Œthelwald seems to have lost Deira to Alchfrith, who is installed there by the victorious Oswiu.

Œthelwald's fate is unknown, as nothing is formally recorded of him after the battle.

Local tradition, however, held that he became a hermit in Kirkdale, North Yorkshire.

The battle has a substantial effect on the relative positions of Northumbria and Mercia.

Mercia's position of dominance, established after the battle of Maserfield, is destroyed, and Northumbrian dominance is restored; …