Cowal before it was the defended medieval homestead of the MacEwens; at first there was a palisaded enclosure, and then a promontory fort with a timber rampart. The remote areas in the north east of Cowal, which were theoretically under the dominion of Clan Lamont, were used by Scottish kings for hunting; indeed, Cowal was the last part of Britain to have wild boar. When King John Balliol was threatened by his rival, Robert de Bruys, Balliol's ally, the king of England, established Henry Percy at Carrick Castle, in the region; likewise Dunoon Castle further south. De Bruys expelled the English
Highland Boundary Fault Border suggests that rocks along both ends of the fault plane are indistinguishable from one another, with no brecciation. Aligned southwest to northeast from Lochranza on Arran, the Highland Boundary Fault bisects Bute and crosses the southeastern parts of the Cowal and Rosneath Peninsulas, as it passes up the Firth of Clyde. It comes ashore near Helensburgh, then continues through Loch Lomond. The loch islands of Inchmurrin, Creinch, Torrinch, and Inchcailloch all form part of the Highland Boundary Fault. From Loch Lomond the Highland Boundary Fault continues to Aberfoyle, then Callander, Comrie and Crieff. It then forms the northern boundary