On the 23rd of April 1014 the Battle of Clontarf took place near Dublin, Ireland.
It consisted of an “army led by Brian Boru, High King of Ireland, against a Norse–Irish alliance comprising the forces of Sigtrygg Silkbeard, King of Dublin; Máel Mórda mac Murchada, King of Leinster; and a Viking army from abroad led by Sigurd of Orkney and Brodir of Mann. It lasted from sunrise to sunset, and ended in a rout of the Viking and Leinster armies.” Wikipedia
Perhaps anything between 7,000 and 9,000 men were killed in the slaughter that day.
The National Museum of Ireland has this excellent exhibition online of the Battle and artefacts uncovered: Clontarf 1014: Brian Boru and the Battle for Dublin
And the Battle would have profound consequences for Orkney with the death in battle of Earl Sigurd II ‘the Stout’
Earl Sigurd married the daughter of Malcolm, King of Scots, and their son was Earl Thorfinn. Earl Sigurd had three other sons, called Sumarlidi, Brusi and Einar Wry-Mouth. Five years after the Battle of Svoldur, Earl Sigurd went to Ireland in support of King Sigtryyg Silk-Beard, leaving his elder sons in charge of the Earldom. Thorfinn he sent over to Scotland to be fostered by the King, the boy’s maternal grandfather. Earl Sigurd arrived in Ireland, joined up with King Sigtrygg and set out to fight King Brian of Ireland. The battle took place on Good Friday. No one would carry the raven banner, so the Earl had to do it himself and he was killed. – Jarl’s Saga
In her excellent book ‘The Northern Earldoms’, Barbara Crawford refers to the forced conversion to Christianity of Sigurd ‘the Stout’ by King Olaf Tryggvesson of Norway, within his own earldom, and his death at the Battle of Clondarf as ‘crucial turning points in the history of the Orkney Earldom’. It marked the end of an era for the Orkney earldom.
The Raven Banner
The Raven banner carried by Sigurd into the battle had been woven by his mother , Eithne. She had endowed it with magic qualities. It would bring victory to the warrior on whose behalf it was carried , but it would also bring death to the man who would be carrying it. Three of Sigurd’s men were killed carrying the banner at Clontarf and as a result he tore it from its staff and wrapped it around himself into battle. He was then killed.
After Sigurd’s death, raiding was no longer the predominant lifestyle of the Orkney earls. From 1014 onwards his son, Thorfinn Sigurdsson becomes established as the most powerful ruler in Orkney and Caithness.