When Earl Sigurd was killed at the Battle of Clontarf, he left four sons: Einar, Brusi, Sumarlidi, and Thorfinn. Thorfinn was only a child, whereas his three brothers were grown men, so the Earldom was divided between the three older brothers. Thorfinn, the only child by his fathers union with the daughter of Malcolm II of Scotland, was appointed to be titular ruler of the Mormaerdom of Caithness by his grandfather.Orkneyinga Saga, c. 13; St Olaf's Saga, c. 96.
