The corpus of evidence for Anglo-Saxon history contains only one narrative of an extended real-life feud. In its most detailed form it appears in a short tract known to historians as De obsessione Dunelmi. The story begins with events that may have taken place in 1006. Uhtred of the House of Bamburgh, the ruling family of the English region north of the River Tees, won a great victory against a Scottish army which had besieged Durham. After mounting the heads of the slain Scots on stakes around Durham's walls, he was summoned south to meet King Æthelred II and rewarded with an earldom that encompassed not just his family's northern heartlands but also what had, until the expulsion and killing of Erik Bloodaxe in 954, been the Scandinavian kingdom of York. Driven, perhaps, by the need to secure local allies in order to rule this region, Uhtred dismissed his first wife – Ecgfritha, daughter of the bishop of Durham – and instead married the daughter of a prominent Yorkshire nobleman named Styr. Styr, however, had a condition for the match: Uhtred was to kill his enemy, Thurbrand the Hold. But Thurbrand struck first. As England succumbed to Scandinavian conquest in the mid-1010s, Uhtred (as De obsessione tells it) remained staunchly loyal to King Æthelred, whose daughter had by this point become his third wife. However, in 1016, once Æthelred had died and Cnut had seized the throne, he had little option but to submit. Having secured safe-conduct from Cnut he travelled to the king's hall and entered his presence, whereupon, apparently as a result of Thurbrand's unspecified treachery, the king's soldiers sprang from their hiding place in a curtained-off section of the hall and slaughtered Uhtred and the forty men who accompanied him.

The next act in the drama is disappointingly vague: after a brief interlude Uhtred's earldom, now shorn of Yorkshire, passed to his son Ealdred, who killed Thurbrand in circumstances which are left obscure. Following this De obsessione provides more detail. There was a prolonged period of hostility in which Earl Ealdred and Carl, Thurband's son, made efforts to ambush and kill one another.