The Danes move northward destroying many churches and monasteries including Whitby Abbey. York is taken on November 1st 866 (and becomes, as Yorvik, the Danish capital in England), and the Danes place a puppet King on the throne in Northumbria called Egbert. Nottingham (in Mercia) and Thetford follow, in 867 and 869 respectively.
Editors. "Northumbria falls to the Vikings". The Literary Encyclopedia. First published 01 May 2009
[http://www.litencyc.com/php/stopics.php?rec=true&UID=6971, accessed 03 May 2016.]