But there was hard fighting to follow. In the spring of 1069 a second and more serious rising broke out in Northumbria. The insurgents took Durham, slew Earl Robert, and sent to ask the aid of the Kings of Scotland and Denmark. They were headed by Waltheof, Earl of Northampton and Huntingdon, the son of that Siward who had vanquished Macbeth. Both the monarchs who had been asked for aid consented to join the rebels. Malcolm Canmore of Scotland had married Margaret, the sister of the Etheling Eadgar, and thought himself bound to aid his brother-in-law. Swegen of Denmark, on the other hand, had hopes of the English crown, to which, as Cnut's successor, he thought he might lay some claim. Waltheof and his army ere long took York, and killed or captured the whole Norman garrison. But after this success the allies drifted apart; Swegen did not care to make Eadgar King of England, and Eadgar's party were angry with the Danes for ravaging and plundering on their own account. When William came up against York with a great host, the Danes took to their ships and left the English unaided. William was too strong for the Northumbrians; he routed them, retook York, and then set to work to punish the country for its twice repeated rebellion. He harried the whole of the fertile Yorkshire plain, from the Humber to the Tees, with fire and sword. The entire population was slain, starved, or driven away. Many fled to Scotland and settled there; others took to the woods and lived like savages. Several years passed before any one ventured forth again to till the wasted lands, and when the great _Domesday Book_ was compiled--nearly twenty years after--it recorded that Yorkshire was still an almost unpeopled wilderness. While William was venting his wrath on the unfortunate Northumbrians, the Danish king, instead of aiding the insurgents, sailed up the Nen to Peterborough, and sacked its great abbey, the pride of the Fenland; this act completely ruined the already failing cause of the English, who would not trust the Danes any longer. [Sidenote: =Final subjugation of the west--Hereward the Wake.=]