The western islands become Scottish
The Treaty of Perth, signed on 2 July 1266 (though traditionally associated with late February), formally transferred the Hebrides and the Isle of Man from Norwegian to Scottish sovereignty. It was the end of four centuries of Norse control over Scotland's western seaboard.
The trigger was the failed Norwegian expedition of 1263. King Haakon IV of Norway had sailed a vast fleet to the Firth of Clyde to reassert Norse authority over the islands. A storm scattered his ships at Largs in Ayrshire, and although the ensuing skirmish was inconclusive, the campaign was a failure. Haakon retreated to Orkney, where he died at the Bishop's Palace in Kirkwall. His successor, Magnus VI, had no appetite for another western adventure.
The treaty was negotiated over three years. Norway ceded the Hebrides and the Isle of Man to Scotland in exchange for an initial payment of 4,000 merks and an annual rent of 100 merks. Scotland agreed to respect the Norse laws and customs of the islanders. The deal was pragmatic — Norway could not defend the western islands, and Scotland could not tolerate a foreign power controlling its coastline.
The Norse legacy in the western islands runs deep. Place names across Skye, Lewis, Harris, and Mull reveal their Scandinavian origins — "ness" (headland), "dale" (valley), "vik" (bay). The Gaelic culture that dominates the Hebrides today absorbed Norse influences over centuries of coexistence. Orkney and Shetland, significantly, remained Norwegian — they would not become Scottish until 1472.