 Celestine MacDonald was the second son of Alexander of Islay, Earl of Ross, 3rd Lord of the Isles and 8th chief of Clan Donald.Celestine MacDonald of Lochalsh, with the support of the MacDonalds of Glengarry unsuccessfully claimed the right to succeed his father as Chief of Clan Donald and Lord of the Isles.Instead the right remained with his older brother John of Islay, Earl of Ross, 4th Lord of the Isles, 9th chief of Clan Donald.