Danish attacks on Norman England

The first was an invasion in 1069–1070 conducted in alliance with various English rebels which succeeded in taking first York and then Ely before the Danes finally accepted a bribe to leave the country.

[1] For many years he was distracted from English concerns by a series of wars in Denmark, where he disputed the throne with first Magnus the Good and then Harald Hardrada; he could not rule his Danish kingdom in peace until 1064.

[5][6] In 1067, after William's coronation but before he had gained effective control of the whole country, English leaders appealed to Sweyn to intervene, and though he made no move he was certainly considered a dangerous threat by the Norman regime.

[11] The army it carried had been recruited not just in Denmark but reportedly in Norway, Frisia, Saxony, Poland and even Lithuania,[12][13] and was commanded not by Sweyn himself but by his sons Harald and Cnut and his brother Asbjørn.

[14] The Danes finally made for the Humber and, effecting a successful landing there, were joined by various English leaders, including Waltheof, Gospatric and Edgar Ætheling, a claimant to the throne.

The Anglo-Saxon Chronicle says that these nobles were accompanied by "all the people of the country", which suggests a general uprising in Yorkshire, and that the combined force advanced on York "riding and marching in high spirits".

[17] After Christmas he proceeded to lay the northern counties waste in a brutal campaign known as the Harrying of the North,[18] while the Danes came to an agreement with him that in return for a large payment and permission to feed themselves by ravaging the eastern coast they would leave in the following spring.

The Anglo-Saxon Chronicle says that "Englishmen from all the fenlands came to meet them, thinking that they were sure to conquer the whole land"; among these was Hereward, a thegn from Lincolnshire, who proceeded to lead a band of men in sacking Peterborough Abbey.

[29][32] The Anglo-Saxon Chronicle claims that "the king gave orders for the coastal districts to be laid waste, so that if his enemies landed they would find nothing which could be quickly seized", but little evidence for this can be found in Domesday Book, and the damage may have been fairly minor.

[34] However, on the other side of the North Sea Cnut's attention was increasingly turning to other problems, such as dealing with his rebellious brother Olaf and with aggression from the Holy Roman Empire.

[29] Arguably, this crisis had important results in motivating William to strengthen his ties with his more prominent subjects by exacting from them an oath of allegiance at Old Sarum, and to better understand his resources by initiating the Domesday Survey,[36][37][38] though the causal link is not accepted by all historians.