 Sigtrygg II Silkbeard Olafsson ( also Sihtric , Sitric and <unk> in Irish texts ; or <unk> and <unk> in Scandinavian texts ) was a Hiberno @-@ Norse king of Dublin ( possibly AD 989 – 994 ; restored or began 995 – 1000 ; restored 1000 and abdicated 1036 ) of the Uí Ímair dynasty . He was caught up in the abortive Leinster revolt of 999 – 1000 , after which he was forced to submit to the King of Munster , Brian Boru . His family also conducted a double marriage alliance with Boru , although he later realigned himself with the main leaders of the Leinster revolt of 1012 – 1014 . He has a prominent role in the 12th @-@ century Irish Cogadh Gaedhil re Gallaibh and the 13th century Icelandic Njal 's Saga , as the main Norse leader at the Battle of Clontarf in 1014 . 
