First recorded invading newly ceded Mercian territories with their allies in 913, the Northampton Danes were initially very successful. However, on their return they were defeated by local Mercian forces near Luton, losing many horses and weapons. In December 914, their strength was further depleted when a number of Northampton Danes submitted to Edward at Bedford. With the loss of Derby and East Anglia and the advance of King Edward, their ruler, Jarl Thurferth, and the men of Northampton and Cambridge submitted to the West Saxons in 917. Thurferth remained the client ruler, and attested four charters of King Æthelstan dated between 930 and 934.
