The Battle of Hatfield Chase was fought in Anglo-Saxon England between the Northumbrians under Edwin and the allied Welsh of Gwynedd under Cadwallon ap Cadfan and Mercians under Penda. It took place on October 12¹, 632 (or 633) and was a decisive victory for the Welsh and Mercians: Edwin was killed and his army was destroyed.

Edwin had conquered Gwynedd a few years before the battle and driven Cadwallon into exile. When the latter returned to Britain, he forged an alliance with Penda, who was then undertaking a siege of Exeter in Dumnonia, and together they recaptured Gwynedd from the Northumbrians. They then invaded Northumbria itself, and the two sides met at Hatfield Chase, north of Doncaster.

The battle was a disaster for Northumbria. With both Edwin and his son Osfrith killed, and his other son Eadfrith captured by Penda (and later executed), the kingdom disintegrated. Eanfrith, a son of the former king Aethelfrith, returned from exile to seize power in one of the Northumbrian sub-kingdoms, Bernicia, while Edwin's cousin Osric took over the other sub-kingdom, Deira. Cadwallon continued to wage a war of ruthless slaughter against the Northumbrians, and was not stopped until the Battle of Heavenfield a year later.

Note

1. Bede gives the date as October 12 in his Ecclesiastical History of the English People (Book II, Chapter XX), but the Anglo-Saxon Chronicle gives the date as October 14.