[2] The redistribution of English estates after the Norman Conquest in 1066 is relatively well-known, but the equally far-reaching grants made to Danish nobles by Cnut the Great less so.

Ansgar's grandfather, Tovi the Proud, was a Danish thegn who came to England with Cnut, and received extensive lands in Oxfordshire,[3] and Middlesex.

As the son of Cnut's Anglo-Saxon predecessor, Æthelred the Unready (966 to 1016), he was backed by Earl Godwin, father of Harold Godwinson, and head of the 'English' faction.

[7] Edward could not afford to isolate so powerful a family, especially one that shared his dislike of the Godwins;[a] his titles were transferred to Ansgar, who was also appointed 'Staller'.

[13] After Edward's death, he faced numerous rivals, the most significant being Harald of Norway, Harold's cousin Sweyn of Denmark, and William, Duke of Normandy.

In June, he left his place of exile in Flanders, and raided Harold's estates in southern England, from the Isle of Wight to Sandwich.

Despite an overwhelming victory at Stamford Bridge on 25 September, William's landing at Pevensey on the 28th forced Harold to return south, where he gathered another army.

[19] He refused; Guy, Bishop of Amiens, who later attended William's coronation, claimed Ansgar negotiated only as a delaying tactic to improve his defences, although this is unconfirmed.

[20] His defence of Southwark in mid-October prevented William entering the city, and forced him to march west, where he secured a crossing at Wallingford.

Ansgar repulsed another attack on London Bridge in early December, before Edgar's principal backer, Edwin, Earl of Mercia, switched sides.