The Battle of Hatfield Chase was fought on 12th October 633, near Doncaster. It resulted in a decisive victory for an alliance of Gwynedd and Mercia led by Cadwallon ap Cadfan and Penda against Northumbria led by Edwin.
The period following the collapse of Roman rule in Britain left the Celtic Britons to fend for themselves. There appears to have been an on-going struggle for territory as kingdoms wrestled and allied themselves with other kingdoms, to define their borders. In the area we now know as Wales, apart from the internal conflict between the indigenous kingdoms, they had to deal with incursions from the Irish and the emerging threat of the Anglo-Saxon expansion from what is now England. In particular, the areas of Powys, Gwent and Gwynedd were constantly threatened by the Anglo Saxon kingdoms of Mercia, Northumbria and Wessex. The Battle of Hatfield Chase is typical of the inter-kingdom rivalry of the time.
A timeline of significant events in the build-up to and the aftermath of The Battle of Hatfield Chase;
c.623 - Edwin is baptised at the Royal Court of Gwynedd.
625 - King Cadfan of Gwynedd dies and his son Cadwallon ap Cadfan succeeds him.
c.626 - A rivalry between Edwin and Cadwallon, which has grown since childhood, reaches a climax. Edwin invades and conquers large parts of Gwynedd, including Anglesey. The defeated Cadwallon is besieged on Puffin Island (off Anglesey), from where he eventually flees to Brittany.
c.630 - The Battle of the Long Mountain (nr Welshpool) King Penda of Mercia allies with Cadwallon who had returned from exile in Brittany and they re-took Gwynedd. Cadwallon then marches to Northumbria and ransacks the kingdom.
633 - Battle of Hatfield Chase - Cadwallon in alliance with Penda, defeated and killed Edwin, which led to the temporary collapse of Northumbria and its division back into its constituent kingdoms of Bernicia and Deira. Cadwallon then slew both King Eanfrith of Bernicia and Osric of Deira rather than negotiate peace terms with them. Oswald succeeded in Bernicia and Acha in Deira.
634 - Battle of Heavenfield (Hexham, Yorkshire, close to Hadrians Wall) Cadwallon marches a huge army north, up the old Roman road, Dere Street into Northumbria to take on Oswald. However, Cadwallon and his army were exhausted after their long journey and Oswald's men, alert and ready for the fight, seized the initiative and despite being outnumbered, killed Cadwallan and defeated his army.