The Battle of the Winwaed was fought on November 15, 655 between King Penda of Mercia and Oswiu of Bernicia, ending in the Mercians' defeat and Penda's death.

Although said to be the most important battle between the northern and southern divisions of the Anglo-Saxons in early Britain, few details are available. For instance, the two armies met on the banks of a river named the Winwaed, but this river has never been identified. (Most likely it was a tributary of the Humber.)

The roots of the battle lay in Penda's success in dominating England in the 630s and 640s. He had defeated and killed Edwin of Northumbria at Hatfield Chase in 633 (in alliance with Cadwallon ap Cadfan) and Oswald of Northumbria at the Battle of Maserfield in 642. In the years after Maserfield, the Mercians apparently campaigned into Bernicia, besieging Bamburgh at one point, and the Northumbrian sub-kingdom of Deira supported Penda during his 655 invasion.

Penda, after gathering allies from East Anglia and Wales, marched with a force "thirty legions strong". Oswiu, who was Oswald's brother but had only succeeded him in Bernicia, the northern part of Northumbria, was besieged by them at a place called Iudeu in the north of his kingdom by Penda. It is almost certain that the Northumbrians were considerably outnumbered by the Mercians and their allies, and Penda seems to have rejected Oswiu's offers of treasure in exchange for peace (at least according to Bede; the Historia Brittonum says he distributed the treasure Oswiu offered among his British allies). According to Bede, before the battle Oswiu prayed to God and promised to make his daughter a nun and grant twelve estates for the construction of monasteries if he was victorious.

Penda army was apparently weakened by desertions. According to the Historia Brittonum, Penda's ally Cadfael ap Cynfeddw of Gwynedd (thereafter remembered as "battle_shirker") abandoned him, along with his army, and Bede says that Aethelwald of Deira withdrew from the battle to await the outcome from a place of safety. Penda was soundly defeated, and both he and the East Anglian king Aethelhere were killed. The battle was fought by the river in the midst of heavy rains, and Bede says that "many more were drowned in the flight than destroyed by the sword". Penda's body is said to have been decapitated.

After the battle, Oswiu took northern Mercia for himself, leaving the southern portion to Penda's son Peada.

External links

• Bede's account of the battle (http://www.winwaed.com/history/winwaed/bede.shtml)