By 1158, Guðrøðr was forced from power by his brother-in-law, Somairle mac Gilla Brigte, who was married to Óláfr's daughter Ragnhildr.

[3] According to the thirteenth- to fourteenth-century Chronicle of Mann, Óláfr was married to Affraic, daughter of Fergus, Lord of Galloway.

[8] In 1153, the thirteenth- to fourteenth-century Chronicle of Mann reports that Óláfr was assassinated by three nephews whilst Guðrøðr was absent in Norway.

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 his father's three killers, putting one to death whilst blinding the other two, and successfully secured the kingship for himself.

[14] 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.