Gradually Dál Riata came to be split between a small number of kin groups, of which the Cenél Loairn controlled Mull and what is now Lorn; the realm of the Cenél Loairn (including Mull) acquired the name Lorn in reference to them. The Cenél Loairn established their main stronghold - Dun Ollaigh - a few miles north of Dun Ormidale. Irish annals record several attacks on Dun Ollaigh, including at least one by the king of Dál Riata, but the circumstances are not clear. Dun Ollaigh remained a stronghold throughout the existence of Dál Riata, but was abandoned shortly afterwards. Norway In the 9th century, Viking invasions led to the destruction of Dál Riata, and its replacement by the Kingdom of the Isles, which became part of the crown of Norway following Norwegian unification. The Kingdom of the Isles was much more extensive than Dál Riata, encompassing also the Outer Hebrides and Skye. To Norway, the island kingdom became known as Suðreyjar (Old Norse, traditionally anglicised as Sodor), meaning southern isles. The former lands of Dal Riata acquired the geographic description Argyle (now Argyll): the Gaelic coast. In the late 11th century, Magnus Barefoot, the Norwegian king, launched a military campaign which, in 1098, led the king of Scotland to quitclaim to Magnus all claim of sovereign authority over the territory of the Kingdom of the Isles. In the mid 12th century, Somerled seized control of the realm from his brother-in-law, the King of the Isles. When he died in 1164 as king, half of the kingdom was retained by his descendants. Lorn appears to have been fallen into possession of his son, Dubgall, eponymous ancestor of the MacDougalls. In the 13th century, the MacDougalls established the twin castles of Aros (in Mull) and Ardtornish (on the mainland, opposite), which together controlled the Sound of Mull. Later in the century, they built Dunstaffnage Castle, a few miles to the north of Dun Ollaigh, as a more comfortable headquarters. At the end of the century, Dun Ollaigh itself was re-fortified, though only as an earthwork. Throughout the early 13th century, the Scottish King, Alexander II, had made aggressive attempts to expand his realm into Suðreyjar, despite Edgar's earlier quitclaim. This naturally led to a period of high hostility between Norway and Scotland, that continued under Alexander III, Alexander II's successor. Haakon died shortly after the indecisive Battle of Largs. In 1266,