Family Sigtrygg was of
Norse and Irish ancestry. and the sister of his successor, King
Máel Mórda of Leinster. Sigtrygg's paternal half-brother was
Glúniairn, or "Iron-knee", who ruled as King of Dublin from 980-989. An incident involving the
ransom of one of Sigtrygg's sons, late in his reign, in which "seven score British horse" were mentioned in the list of demands, The
Irish annals record little information about Sigtrygg, his family or Dublin during these first five years of his reign.
Benjamin Hudson claims this was because of the arrival of the future
King of Norway,
Olaf Tryggvason, who took up residence in Dublin for a few years after marrying Sigtrygg's sister Gytha. Hudson argues that Tryggvason's return to
Norway in 994 coincided with the temporary expulsion of Sigtrygg from Dublin by his rival
Ivar of Waterford. Ivar may have already ruled there from 989 until forced-out by Sigtrygg in 993; much depends on interpretation. Nevertheless, Sigtrygg was back within a year. In 995, he and his nephew, Muirchertach Ua Congalaich, attacked the church at
Donaghpatrick in
County Meath. while the
Annals of Inisfallen date Brian's capture of the city to 1 January 1000. In any case, in 1000, Brian plundered the city, burned the Norse fortress, and expelled Sigtrygg. Both tribes refused to help him. Sigtrygg never forgot the Ulaid's refusal of aid when he fled from Dublin and, in 1002, he had his revenge when his soldiers served in Brian's campaign against the Ulaid and ravaged their lands. They served under Brian against the Ulaid again in 1005, and against the Northern Uí Néill in 1006 and 1007. Only fragments survive of the verses in the
Sigtryggsdrápa, a
drápa composed by the skald
Gunnlaug Illugason while visiting Sigtrygg's court. Around 1012, relations between Brian and Leinster had become so strained that revolt broke out among the Leinstermen. Sigtrygg arrived in
Orkney for Sigurd's Yule feast, where he sat in a high seat between the two brothers-in-law, Earl Sigurd of Orkney and Earl Gilli of the Southern Isles. Despite Sigurd's initial hesitance, and against the advice of his men, he eventually agreed to arrive in Dublin by
Palm Sunday with all his men, on the condition that if Brian was slain, Sigurd would marry Gormflaith and become King of Ireland. where he promised Bróðir too that, if successful, he would be allowed to marry Gormflaith and become King of Ireland; the terms of this agreement were kept-secret. Óspak was dissatisfied with the arrangement, and refused to "fight against so good a king". According to Irish sources, Sigtrygg did not take part in the battle, but held his garrison in reserve in Dublin. The
Cogadh Gaedhil re Gallaibh records that Sigtrygg was able to observe the progress of the battle and the movement of the battle standards from the ramparts of his fortress. As the modern Irish medievalist historian
Donnchadh Ó Corráin notes, Sigtrygg "wisely kept within the city and lived to tell the tale". ''Njal's Saga'' records that Sigtrygg was on the wing opposite Óspak of Man for the whole battle, and that Óspak eventually put the king to flight.
Reign after Clontarf Immediately after Clontarf, Sigtrygg's fortunes appear to have declined, even though he emerged with his kingdom intact. Máel Sechnaill, now again recognised as high king, was undoubtedly the battle's main beneficiary. These captives would either have been ransomed or sold off into Dublin's lucrative slave trade. When Sigtrygg raided south in 1021, he was defeated at
Delgany in
County Wicklow In 1022, the Dublin fleet sailed north against the Ulaid, only to be destroyed in a naval battle against
Niall mac Eochaid, after which the Norse crews and ships were taken prisoner. The great Irish princes began to compete for the High Kingship, and the political situation in Ireland became chaotic as there was no clear choice for supremacy. Sigtrygg formed a new alliance with the men of
Brega. In 1027, Sigtrygg's son
Olaf joined Donnchad of Brega in a raid on Staholmock, County Meath. Sigtrygg rallied to the fight again at Lickblaw (near
Castlepollard,
Westmeath) where Donnchad and Roen were slain. Sigtrygg was forced to pay a ransom of 1,200 cows, 140 British horses, 60 ounces of gold and of silver, "the sword of Carlus", the Irish
hostages of Leinster and
Leath Cuinn, "four hostages to Ua Riagain as a security for peace, and the full value of the life of the third hostage". The incident illustrates the importance of ransoming noble captives, as a means of political manipulation, increasing one's own revenues and exhausting the resources of one's foes. A Dublin colony was established in
Gwynedd, and for the following years Sigtrygg was at the height of his power. In 1035, he plundered the celebrated stone church of
Ardbraccan in Meath, burned 200 men inside, and carried another 200 off into captivity. Ragnall was the grandson of the Ivar, Sigtrygg's earliest rival, who had contested for Dublin decades before.
Echmarcach mac Ragnaill,
King of the Isles forced Sigtrygg to abdicate in 1036. Sigtrygg died in exile, at an unknown place, in 1042. ==Issue and legacy==