Battle of Maserfield: Penda of Mercia defeats and kills Oswald of Northumbria.
The Battle of Maserfield (Welsh: Cad Maes Cogwy) was fought on 5 August 641 or 642 (642 according to Ward) between the Anglo-Saxon kings Oswald of Northumbria and Penda of Mercia, ending in Oswald's defeat, death, and dismemberment. The location was also known as Cogwy in Welsh, with Welshmen from Pengwern participating in the battle (according to the probably ninth-century Canu Heledd), probably as allies of the Mercians. Bede reports the commonly accepted date given above; the Welsh Annales Cambriae is generally considered incorrect in giving the year of the battle as 644. The site of the battle is traditionally identified with Oswestry; arguments have been made for and against the accuracy of this identification.