Battle of Hatfield Chase

The Battle of Hatfield Chase was fought on 12 October 633 between Edwin of Northumbria and an alliance led by Cadwallon ap Cadfan of Gwynedd and Penda of Mercia. Edwin was killed and his army defeated, bringing the powerful Northumbrian regime he had assembled to an abrupt end.

The victory allowed Cadwallon’s forces to campaign across Northumbria while Bernicia and Deira again came under separate rulers. The resulting political and military crisis continued until Oswald defeated Cadwallon at the Battle of Heavenfield in 634.

It should be assigned in place of its broader Mercian Expansion under Penda parent when the battle and its immediate consequences are central.