Ask an Irishman about the Battle of Clontarf in 1014, and he'll probably tell you that's the battle where Brian Boru, Ireland's heroic high king, drove the Viking invaders from Ireland. The real story is not quite so simple.

Brian Boru wasn't the legitimate high king in terms of the traditional Irish monarchy- which never had nationwide power in the first place. Brian Boru was an usurper, the upstart chief of a tribe called the Dalcassians, who had managed to seize power in a coup.

He was known as “Boru”- meaning “of the cattle tribute”- because he had succeeded in imposing a cattle tribute on the men of Leinster by force of arms, something many other Irish kings had tried and failed to do.

Eventually, the men of Leinster rebelled under their king Mael Morda, and he turned to his allies the “Gall Gaels” of Dublin, Mann and the Hebrides. These men, although of Viking origin, had intermarried with Gaels to such an extent that they were as much Gaelic as they were Norse. Many of the later Highland clans descended from them. Brian Boru marched to meet them with his own army of Gaelic warriors and Norse mercenaries.

The Battle of Clontarf, in other words, was a fight between two Irish kings and their Viking and Scottish allies- not a war of liberation in which the Irish freed themselves from the Vikings. The one element of truth in the traditional version is the battle broke the political power of the men of Dublin, with the result that the Norse were no longer serious players on the Irish political scene after this date.