In Haraldr's absence, Magnús and a relation of his, Eóghan Mac Dubhghaill, King in the Isles, unsuccessfully attempted to conquer Mann.

Although his forces gained strength as they sailed southwards, the Norwegian king received only lukewarm support from many of his Norse-Gaelic vassals—in fact, Magnús was one of the few who came out whole-heartedly for Hákon.

Magnús' subsequent submission to the Scottish king, and the homage rendered for his lands, symbolises the failure of Hákon's campaign, and marks the complete collapse of Norwegian influence in the Isles.

His killer is identified by a contemporary source as a knight named Ívarr who may have been an ally of Rǫgnvaldr Óláfsson's second cousin once removed, Haraldr Guðrøðarson (fl.

[14] In 1248, Eóghan and his second cousin, Dubhghall mac Ruaidhrí (died 1268), travelled to Hákon in Norway and requested the title of king in the Hebrides.

[19] The chronicle states that the invaders made landfall at Ronaldsway, and entered into negotiations with the Manx people; although, when it was learned that Eóghan styled himself "King of the Isles", the Manxmen took offence and broke off all dialogue.

[20] The chronicle indicates that Eóghan had his men form-up on St Michael's Isle,[17] an island that was attached to Mann by a tidal causeway.

[18] As evening drew near, the chronicle records that an accomplice of the knight Ívarr led a Manx assault on the island and routed the invading forces.

For example, Henry is known to have written letters to Alexander, Hákon, and Llywelyn ap Gruffudd (died 1282), the co-ruler of Gwynedd, ordering them not allow their men invade Mann in Magnús' absence there in 1254.

Alexander's sudden death in the Hebrides brought an abrupt end to his westward invasion, and it was not until the 1260s that a Scottish king again attempted to impose his authority into the Isles.

Negotiations proved fruitless, and the following year William I, Earl of Ross (died 1274) is recorded to have launched a vicious attack on Skye.

[35] The saga states that Hákon's fleet then sailed south to Kerrera, where Dubhghall and Magnús amongst others, were sent to lead fifty ships towards Kintyre, while a smaller group was sent to Bute.

[38] The fleet sent to Kintyre was likely tasked with obtaining the allegiance of Aonghus Mór mac Domhnaill, Lord of Islay (died c.1293) and a certain Murchadh,[39] both who are stated by the saga to have afterwards submitted to Hákon.

[46] At Gigha, the saga relates that Eóghan surrendered himself to Hákon, and informed the Norwegian king that he had decided to side with the Scots from whom he held a larger grant of lands.

[48] The saga indicates that negotiations started peacefully enough, although as time drew on, and the weather grew worse, a time-pressed Hákon broke off all dialogue.

[54] While Lennox was being plundered,[55] Hákon and his main force, stationed between the Cumbraes and the Scottish mainland,[56] were occupied with the events surrounding the Battle of Largs, between 30 September and 3 October.

[57] Although claimed by later Scottish chroniclers as a great victory, in reality the so-called battle was nothing more than "a series of disorderly skirmishes", with relatively few casualties that achieved little for either side.

At Mull, he parted with his Norse-Gaelic lords: Dubhghall was rewarded with Eóghan's former island-domain; Murchad was given Arran, and a certain Ruaidrí was given Bute, titles in name only since King Alexander quickly reasserted control.

[58][note 7] The Norwegian fleet left the Hebrides and reached Orkney by the end of October, where an ill Hákon died in mid December.

Without any protection from his Norwegian overlord,[64] or from Henry III (who was held captive at the time),[65][note 8] Magnús had no choice but to submit to the demands of the powerful King of Scots.

The two monarchs met at Dumfries, where Magnús resigned his crown, swore oaths to Alexander, rendered homage, and surrendered hostages.

Although no seals of the dynasty now survive, there exists several seventeenth- and eighteenth-century descriptions and depictions of ones believed to have belonged to Magnús' uncle Rǫgnvaldr, and brother Haraldr.

This limited evidence suggests that, in the twelfth- and thirteenth centuries, the kings of the dynasty bore a sailing ship upon their seals, which would have likely represented the clinker-built galley utilised in the Isles at the time.

[77] Analysis of the document reveals that the main scribe's last entry dates to 1257, in an account which records the dedication of the Abbey of St Mary of Rushen in the presence of Magnús and Richard, Bishop of the Isles.

[13][note 13] As the last of a long line of Norse-Gaelic rulers of Mann, his death ended the island's so-called "golden-age" of Scandinavian sea-kings.

Other conditions stipulated that the inhabitants of the islands would be subject to laws of Scotland; that they were not to be punished for their actions previous to the treaty; and that they were free to remain or leave their possessions peacefully.

[95][note 14] Guðrøðr may very well have been slain in the defeat,[98] although one source, the continuation of Historia rerum Anglicarum, states that he, his wife and his followers escaped the carnage to Wales.

[99][note 15] By the end of the thirteenth century, the islands once ruled by Magnús and his fellow members of the Crovan dynasty before him, were incorporated into the Scottish realm.

This sheriffdom included the seaboard north of Ardnamurchan (Wester Ross and Kintail), and the islands of Skye, Lewis, Uist, Barra, Eigg, and Rum.