The Battle of Degsastan was fought in 603 AD between the Anglo-Saxon king Aethelfrith of Northumbria and the Scots under Aedan of Dalriada. Aethelfrith carried the day, but we know almost nothing else about the battle, not even where "Degsastan" was supposed to be.
Aethelfrith and went on to establish Northumbria as the union of Bernicia and Deira, while the Scots refrained from attacking the English for many years thereafter.
