Anglo-Saxon Chronicle. 21 Mar 867. Late in the year, however, they returned to their allegiance, and they were now fighting against the common enemy; having collected a vast force, with which they fought the army [Battle of York] at York [Map]; and breaking open the town, some of them entered in. Then was there an immense slaughter of the Northumbrians, some within and some without; and both the kings [Osberht King of Northumbria and Ælla King of Northumbria] were slain on the spot. The survivors made peace with the army.