The year of the Battle of Clontarf, 1014, is not in any doubt, as our annals are unanimous on this point, but the trad-itional belief that it took place on Good Friday, 23 April, is sometimes nowadays thought to be a later notion: was it concocted to liken the death of the Christian king, Brian Boru, saving his nation by triumphing over a supposed heathen enemy, to Christ’s salvation of mankind by His death at Calvary? The fact is that the Good Friday date is not given in the earlier and more reliable annal accounts of the battle, the Annals of Inisfallen and the Annals of Ulster.
The famous account of Brian’s life Cogadh Gáedhel re Gallaibh (‘The war of the Irish against the Foreigners’), which latest research indicates may have been written within living memory of the battle in the 1070s or 1080s, states that ‘it was on the Friday before Easter that the battle was fought, viz. the ninth of the Kalends of May [i.e. 23 April]’. Unfortunately, for this part of the story we only have one version of the text—in a manuscript from the seventeenth century in the hand of Micheál Ó Cléirigh, one of the Four Masters—and so it might still be argued that this is a later invention.
On the other hand, the Irish monk Marianus Scottus wrote a chron-icle while in Germany in the decades before his death in 1082, and he unambiguously testifies that Brian was killed on 23 April while preparing for Easter, having ‘hands and mind focused on God (Brian, rex Hiberniae, parasceue Paschae, feria vi, ix Kal. Maii, manibus et mente ad Deum intentus, occiditur)’. Similarly, Icelandic sources written in the thirteenth century but drawing on earlier material brought from Ireland have it that Brian did not take part in the battle because he refused to fight on Good Friday.