Oswulf’s family ruled Bamburgh from 954 until 1041, though their independence may have been compromised after 1041 when Siward the Stout killed Eadwulf and gained hegemony over the north.
In 1065, Morcar succeeded Tostig as ealdorman of Northumbria and nominal overlord of Oswulf, ruling the portion north of the River Tyne.
Because Copsi was seen as an invader and a tax-gatherer for William, he was deeply unpopular among the Northumbrians north and south of the Tyne, and Oswulf had no trouble in gathering recruits.
However, in the autumn of 1067, Oswulf, who appears to have been carrying out his duties as earl, intercepted an outlaw and was run through by the man’s spear.
He was succeeded as earl by his cousin, Gospatric, who allegedly paid King William for the latter's recognition of his earldom.