the year. Upon Guðrøðr's reestablishment in the Isles, the realm was again divided between him and Somairle's descendants, in a partitioning that stemmed from Somairle's coup in 1156. The Battle of Renfrew may have been Malcolm's greatest victory. It is certainly the last major event of his reign on record. Background At an uncertain point in the mid twelfth century, perhaps in about 1140, Somairle mac Gilla Brigte married Ragnhildr, daughter of Óláfr Guðrøðarson, King of the Isles. This union had severe repercussions on the later history of the Kingdom of the Isles, as it gave Somairle's descendants—Clann Somairle—a claim to the kingship by way of Ragnhildr's royal descent. The year 1153 marked a watershed in the history of the Isles. Not only did David I, King of Scotland die late in May, but the thirteenth- to fourteenth-century Chronicle of Mann reports that Óláfr was assassinated in June, whilst his son, Guðrøðr, was absent in Norway. Within months of his father's assassination, Guðrøðr executed his vengeance. According to the chronicle, he journeyed from Norway to Orkney, enstrengthened by Norwegian military support, and was unanimously acclaimed as king by the leading Islesmen. He is then stated to have continued on to Mann, where he overcame three kin-slaying cousins, and successfully secured the kingship for himself. In 1155 or 1156, the Chronicle of Mann reveals that Somairle conducted a coup against Guðrøðr, specifying that Somairle's son, Dubgall, was produced as a replacement to Guðrøðr's rule. Late in 1156, on the night of 5/6 January, Somairle and Guðrøðr finally clashed in a bloody but inconclusive sea-battle. According to the chronicle, when the clash finally concluded the feuding brothers-in-law divided the Kingdom of the Isles between themselves. Two years later, the chronicle reveals that Somairle invaded Mann and drove Guðrøðr from the kingship into exile. With Guðrøðr gone, it appears that either Dubgall or Somairle became King of the Isles. Although the young Dubgall may well have been the nominal monarch, the chronicle makes it clear that it was Somairle who possessed the real power. Certainly, Irish sources regard Somairle as a king by the end of his career. Battle The Battle of Renfrew is attested by sources such as: the fourteenth-century Annals of Tigernach, the fifteenth- to sixteenth-century Annals of Ulster, the twelfth-century Carmen de Morte Sumerledi, the thirteenth-century Chronica of Roger de Hoveden, the twelfth- to thirteenth-century Chronicle of Holyrood, the thirteenth-