Who was the son of Waltheof I that was killed by Thurbrand the Hold?
Thurbrand the Hold Thurbrand (Old English: "Þūrbrand" ; fl. 1010s), nicknamed "the Hold", was a Northumbrian magnate in the early 11th-century. Perhaps based in Holderness and East Yorkshire, Thurbrand was recorded as the killer of Uhtred the Bold, Earl of Northumbria. The killing appears to have been part of the war between Sweyn Forkbeard and Cnut the Great against the English king Æthelred the Unready, Uhtred being the latter's chief Northumbrian supporter. Thurbrand may also have attested a charter of 1009 and given a horse to Æthelred's son Æthelstan Ætheling. The killing is the first known act, if it did not initiate, a bloodfeud between Thurbrand's family and Uhtred going into the time of Earl Waltheof. It is possible that Holderness took its name because of Thurbrand's presence or ownership of the peninsula.
William Adelin William Ætheling (] ; 5 August 1103 – 25 November 1120), designated or titled Adelin (alternately rendered as "Adelinus", "Adelingus", "A(u)delin" or other Latinised Norman-French variants of "Ætheling"), was the son of Henry I of England by his wife Matilda of Scotland, and was thus heir apparent to the throne. His early death without issue caused a succession crisis, known in history as The Anarchy.