From Dugall, the brother of Reginald, are descended the Clan MacDugall. Reginald was liberal to the church and founded the monastery of Saddell. His son, Donald "de Isla," succeeded him, and under his guidance the clan attained great eminence. He died in 1269 and was succeeded by his son Angus who supported Haco, but did not suffer from the latter's defeat at Largs in 1263. Angus Og supported Bruce and increased the family possessions considerably. His son, John, assumed the title of Lord of the Isles in 1354. His son Donald of Harlow followed as 2nd Lord of the Isles.
He married the only daughter of the Countess of Ross, and claimed the Earldom of Ross, but later renounced this claim and became a vassal of the crown. He died in 1423, and his son Alexander succeeded and became Earl of Ross on the death of his mother. The title was acknowledged by the Crown in 1430. For a period he was Justiciar of Scotland. He died in 1448 and was succeeded by his son John, 4th and last Lord of the Isles, who rebelled against the Crown and declared his independence. After a long stormy life, during which the Earldom of Ross was annexed to the crown, And the Lordship of the Isles forfeited, John died without legitimate issue in 1498.
Text taken from Robert Bain's "The Clans and Tartans of Scotland"