Svein’s band of eighty warriors was large enough to make him a major power in Orkney, but he seems to have had no political ambitions beyond maintaining his autonomy. When the dispute between the earls broke out, Svein sided with Erlend so that he could legitimately plunder Orkney and Shetland, capturing ships belonging to Harald and Rognvald and stealing their rents and taxes. Once Erlend was dead, he and his victims were quite easily reconciled. Svein, after all, had his uses and, as there was little they could do about him anyway, it was best to be pragmatic. Sometimes the earls loaned him ships for his raids for a cut of the plunder and, if there was someone they wanted killing, Svein was usually happy to oblige, being well-aware that such favours could always be called in. Around 1170, Earl Harald urged Svein to give up raiding, telling him that ‘most troublemakers are fated to end up dead unless they stop of their own free will’. All too aware that his high status could only be maintained by a continuous stream of plunder, Svein continued, meeting a predictably violent end in 1171 when he joined Asculf Ragnaldsson, the exiled Ostman king of Dublin, in his doomed attempt to recapture the city from the Anglo-Normans.
Earl Harald’s sole rule saw the gradual decline of the Earldom of Orkney. In 1194, Harald supported an unsuccessful rebellion against King Sverre of Norway and was once again forced to recognise the overlordship of the Norwegian crown. As punishment for the rebellion, Sverre took Shetland under direct royal authority. The earldom’s possessions on the Scottish mainland, Caithness and Sutherland, also came under growing pressure from the kings of Scotland. Scottish influence in Orkney had grown almost imperceptibly as a result of intermarriage between the Norse and Scottish aristocracies. Harald himself was the product of one such marriage: his mother was the daughter of Earl Håkon Paulsson and his father was Matad the mormaer of Atholl, through whom he had inherited Scottish royal blood. Because of his family connections, Harald’s claim to a share of the earldom had been supported by King David I. David’s successors, likewise, used family disputes in the earldom to increase their influence there. In 1201, King William the Lion of Scotland used a dispute over the rights of the bishopric of Caithness as a pretext to invade the province in overwhelming force. Harald kept the provinces but was forced to surrender a quarter of their revenues to King William. This prepared the ground for the definitive Scottish takeover of Caithness and Sutherland after Harald’s son and successor Jon Haraldsson was murdered in Thurso in 1231. Jon’s death brought the direct line of Norse earls to an end (his family was lost at sea on their way to Norway after his murder). In 1236, Håkon IV (r. 1217 – 63) appointed Magnus mac Gille Brigte, the mormaer of Caithness, as earl. Magnus was descended from the Norse earls through his mother but was culturally a Scottish Gael. For the remainder of its history the earldom would be ruled by Scottish families, although it remained Norse in culture, language and sovereignty.
The situation further south in Man and the Hebrides in the years immediately following Magnus Barefoot’s death is far from clear because the main source, the Cronica Regum Mannie et Insularum (‘Chronicles of the Kings of Man and the Isles’) is chronologically unreliable. It is likely, however, that the island was under Irish control until 1114 when Olaf Godredsson (r. c. 1114 – 53) returned from his exile in England and, with Henry I’s support, restored Norse rule in Man and the Isles. Olaf strengthened his position with marriage alliances with neighbouring rulers, all of whom had an interest in containing the power of the Scots kings. Olaf’s first wife was Ingibjorg, a daughter of Earl Håkon Paulsson of Orkney, and he married one of his daughters by this marriage, Ragnhild, to Somerled, the Norse-Gaelic king of Argyll. Olaf’s second marriage was to Affraic, daughter of Fergus, the king of Galloway, and his wife, an unnamed illegitimate daughter of Henry I of England. Olaf’s wide-ranging alliances gave his kingdom security. The Manx chronicle describes him as ‘a man of peace… in such close alliance with the kings of Ireland and Scotland that no one dared disturb the Kingdom of the Isles in his lifetime.’
In 1152, Olaf sent his son Godred to pay homage to King Inge in Norway. In Godred’s absence the three sons of Olaf’s brother Harald, who had been exiled in Dublin, gathered a fleet and invaded the Isle of Man to demand that their uncle give them half of the kingdom. Olaf agreed to meet the brothers at Ramsey to discuss their demands. However, the meeting was a trap and Olaf was taken by surprise and beheaded. The Haraldssons had little popular support and they did not rule the island for long. Godred returned the next year, raised a large army in the Hebrides, and captured the brothers, blinding two of them and killing the third. According to the Manx chronicle, once he had crushed all opposition, Godred began to rule like a tyrant. His popularity may also have suffered as a result of a failed attempt to seize Dublin and other unsuccessful interventions in Irish politics. In 1155, a powerful Norse-Gaelic chieftain from the Hebrides, Thorfinn macOttar, went to Somerled and asked him to make his young son Dugald king over the Isles in place of Godred. Somerled obligingly handed his son over to Thorfinn, who duly paraded the boy through the isles, subjecting them to his rule and taking hostages. Godred acted quickly when the news of Thorfinn’s coup reached him, raising a fleet and sailing to the Hebrides to regain control, even though it was mid-winter. Somerled raised a fleet of eighty ships and fell upon Godred’s fleet on the night of Epiphany (5 – 6 January) 1156. The location of the battle is not known but it has been plausibly identified as being off the west coast of Islay. The fighting was hard but the outcome was indecisive. When day dawned the two leaders negotiated an agreement by which Godred ceded all of the Hebrides to Somerled, except for Skye, Harris and Lewis. This was not enough for Somerled. Two years later he landed at Ramsey in the Isle of Man with a fleet of fifty-three ships and forced Godred to flee into exile to Norway. Although he had ostensibly gone to war against Godred on behalf of his son, it seems that Somerled took the whole of the Kingdom of Man and the Isles under his personal rule and began to style himself Rex Insularum – ‘King of the Isles’. Somerled’s victory began the final stage of the assimilation of the Norse of the Hebrides into the indigenous Gaelic population.
Several major Highland clans, including Clan MacDougall, Clan Donald, Clan MacRory and Clan MacAlister, consider Somerled to be their direct patrilinear ancestor and later clan histories have cast him in the role of champion of the Gaels against both the Norse and the feudalising Scottish monarchy. In reality Somerled was a typical chieftain of his time and place, defending his own lands and opportunistically raiding the lands of his neighbours irrespective of whether they were Gaels or Norse: his name is derived from Old Norse Sumarliði, meaning ‘summer warrior’, a common alternative name for ‘Viking’. Irish annals and later clan histories preserve several, mutually contradictory, traditions about Somerled’s ancestry but modern genetic studies have shown fairly conclusively that his patrilinear ancestors were ultimately Norse. Five chiefs of different branches of Clan Donald, who can all trace their descent back to Somerled, shared a distinctive genetic marker, identified as a sub-group of haplogroup (i.e. a distinctive sequence of genes) M-17, on the Y chromosome, which is inherited only through the male line. This marker is common in Norway but rare in indigenous British and Irish populations. The same marker was found to be shared by 40 per cent of men with the surname MacAlister, 30 per cent of MacDougalls, and 18 per cent of MacRorys: Somerled may have a lot of descendents. Although Somerled had Norse ancestry, his family had travelled the road to full integration with the local Gaels some generations before he was born as his father and grandfather had Gaelic names. Somerled was much more a Gael than a Norseman in language, culture and identity.