Dunollie Castle is believed to have been fortified since the 6th century and became the seat of the chief of Clan MacDougall. Duncan also built Ardchattan Priory and it was here that the MacDougall chiefs were buried until 1737. Ewan's possessions on the islands were held from the king of Norway, whilst his possessions on the mainland were held from the king of Scotland. This made it hard for him to remain loyal to both. In 1263 Haakon IV of Norway arrived with a huge fleet off the coast of Oban for an invasion of the west coast of Scotland. However, Ewan decided not to join the invasion and thanks to old blood ties Haakon left him in peace. The Battle of Largs then took place and Ewan joined the side of Scots and attacked part of the Norse fleet. The Vikings were utterly defeated and three years later Norway ceded all of the Hebrides to Scotland. The MacDougall's influence in Argyll brought them into conflict with the Clan Campbell. In 1294 John MacDougall of Argyll led the Clan MacDougall against the Clan Campbell at the Battle of Red Ford, where Sir Colin Campbell was killed but there were considerable losses on both sides. The fourth chief of Clan MacDougall married a sister of John II Comyn, Lord of Badenoch (the "Black Comyn"), whose son, John III Comyn, Lord of Badenoch (the "Red Comyn") was stabbed to death by Robert the Bruce in the church of Greyfriars in Dumfries in 1306, and this brought the MacDougalls into conflict with the Bruces. The MacDougalls who had supported William Wallace in the cause of Scottish independence now found themselves in a blood feud with the Clan Bruce, whose cause was also of Scottish Independence. Shortly after Robert the Bruce's coronation at Scone he was forced by the English to retreat into Argyll, in an attempt to reach his Clan Campbell allies. However, the Clan MacDougall surprised the Bruce and defeated him in what was known as the Battle of Dalrigh. The king escaped but left behind what was described as a magnificent example of Celtic jewellery, known as the "Brooch of Lorne" and it became one of the Clan MacDougall's great treasures. Three years later Robert the Bruce led three thousand battle hardened veterans into Argyll against the MacDougalls. John MacDougall of Lorne set an ambush for them but in the ensuing Battle of the Pass of Brander the MacDougalls were defeated and forced to flee.