‘Blue-black’, ‘Black stream’
A river in Britain which was, according to Nennius, the site of Arthur’s second, third, fourth, and fifth battles against the Saxons. When the new king, aged just fifteen and having newly ascended the throne, defeated the Saxon leader Colgrin and a mixed force of Saxons, Scots and Picts. Colgrin took refuge after the fourth battle in York, and Arthur then laid siege to him there.
As in all of the twelve battles, Arthur was victorious. Nennius places the river in Linnuis, which may be the province of Lindsey in Lincolnshire, though no river by this name is known there.
There are scattered rivers with similar names in Scotland, including a Dunglas in Lothian, which may be meant by Linnuis, but it is unlikley that Arthur would have fought the Saxons so far north. He may have been fighting Picts. Geoffrey of Monmouth includes the fight – condensing Nennius’s four battles into one – and seems to identify it with the River Duglas in Lancashire. The Saxons fled to the nearby city of York after their defeat.