Battle of Hatfield Chase
The Battle of Hatfield Chase (Old English: Hæðfeld; Old Welsh: Meigen) was fought on 12 October 633 It pitted the Northumbrians against an alliance of Gwynedd and Mercia. The Northumbrians were led by Edwin and the Gwynedd-Mercian alliance was led by Cadwallon ap Cadfan and Penda. The site of the battle was a marshy area about 8 miles (13 km) northeast of Doncaster on the south bank of the River Don, though this location has been disputed. It was a decisive victory for Gwynedd and the Mercians: Edwin was killed and his army defeated, leading to the temporary collapse of Northumbria.