Premise: Dunyvaig Castle, (Scottish Gaelic: "Dùn Naomhaig" , Anglicised "Fort of the galleys", also known as "Dunnyveg") is located on the south side of Islay, in Argyll, Scotland, on the shore of Lagavulin Bay, 4 km from Port Ellen. The castle was once a naval base of the Lord of the Isles, chiefs of Clan Donald. It was held by the chiefs of the Clan MacDonald of Dunnyveg.
Hypothesis: Clan MacDonald has no chiefs.