Page "Causantín mac Cináeda" Paragraph 5

Viking activity in Britain increased in 865 when the Great Heathen Army, probably a part of the forces which had been active in Francia, landed in East Anglia.

The following year, having obtained tribute from the East Anglian King Edmund, the Great Army moved north, seizing York, chief city of the Northumbrians.

The Great Army defeated an attack on York by the two rivals for the Northumbrian throne, Osberht and Ælla, who had put aside their differences in the face of a common enemy.

Both would-be kings were killed in the failed assault, probably on 21 March 867.

Following this, the leaders of the Great Army are said to have installed one Ecgberht as king of the Northumbrians.

Their next target was Mercia where King Burgred, aided by his brother-in-law King Æthelred of Wessex, drove them off.