Battle of Clontarf, oil on canvas. Painting by Hugh Frazer, 1826
The legendary Battle of Clontarf at Dublin (Ath Cliath) in 1014 – instigated in part by the king of that realm, Sigtrygg Silkbeard Olafsson (c. 970-1042) – is known for fracturing Viking rule in Ireland but a litany of noblemen and kings on both sides were slain there – including Ireland’s elder high king Brian Boru. The background of why and how Sigtrygg amassed the Viking army against the Irish is generally overlooked because it involved Brian’s former wife Gormlaith (Gormflaith), the daughter of the king of Leister who first married Amlaíb mac Sitric (Olaf Cuaran) – a Norse-Gael king of Northumbria and Dublin. Gormlaith, whose name appears in the thirteenth-century Icelandic Njal’s saga as “Kormlada,” happened to be Sigtrygg’s mother.
According to James Henthorn Todd – a nineteenth-century Irish historian who translated the twelfth-century Cogadh Gáedel re Gallaib (The invasions of Ireland by the Danes and other Norsemen) – Sigtrygg (“Sitric” in Irish) was defeated by Brian in 999 at the Battle of Glenn Mama, and after submitting became “necessary for the accomplishment of Brian’s ambitious plans. An alliance was accordingly made with him. It was probably on this occasion that Brian gave his daughter to Sitric in marriage, and possibly formed his own connexion with Sitric’s mother, Gormflaith…” According to the Cogadh, Sigtrygg remained king of Dublin after Clontarf because he and his wife (Brian’s daughter) watched from the safety of a nearby tower as scores of noblemen and kings, and thousands of warriors, slaughtered each other that day from sunrise to sunset.
The End of Peace
For a decade relative peace between Sigtrygg and Brian existed until violence broke out in Meath, and Sigtrygg sanctioned an attack in 1013 on coastal Cork in Munster – the center of Brian’s power. As a result, that autumn Brian and Mael Sechnaill – another high king who defeated Sigtrygg’s father at the Battle of Tara (980) and also helped Brian at Glenn Mama – sieged Dublin until the winter. Following the siege, Sigtrygg went to the Earl of Orkney, Sigurd Hlodvirsson, and the famed warrior of the Isle of Man, Brodir (Bróðir) – offering them kingships if they helped him. According to Njal’s saga, Gormlaith “egged on her son Sigtrygg very much to kill King Brian, and she now sent him to Earl Sigurd to beg for help.” The saga also describes Gormlaith as…
…the fairest of all women, and best gifted in everything that was not in her own power, but it was the talk of men that she did all things ill over which she had any power. Brian was the name of the king who first had her to wife, but they were then parted. He was the best-natured of all kings. …Kormlada was not the mother of King Brian’s children, and so grim was she against King Brian after their parting, that she would gladly have him dead.
Breaking Through the Shieldburg
There are few kind words in the Cogadh describing the Viking army: “Danars of all the west of Europe, having no reverence… or mercy for God or for man, for church or for sanctuary… villanous, ferocious, plundering, hard-hearted, foreign… Danmarkians, selling and hiring themselves for gold and silver…” The Cogadh also notes the Vikings wore mail, which compensated for their lesser numbers. “And there was not one villain or robber… who had not polished, strong, triple-plated, glittering armour of refined iron… encasing their sides and bodies from head to foot.” The unknown author of the Cogadh, which eulogized Brian, described the battle in mystic terms:
And there arose a wild, impetuous, precipitate, furious, dark, frightful, voracious, merciless… vulture, screaming and fluttering over their heads. And there arose also… the maniacs of the valleys, and the witches, and the goblins, and the ancient birds, and the destroying demons of the air and of the firmament, and the feeble demoniac phantom host; and they were screaming and comparing the valour and combat of both parties. …I could compare it only to the variegated, boundless, wonderful firmament, that had cast a heavy sparkling shower of flaming stars over the surface of the earth; or to the startling fire-darting roar of the clouds and the heavenly orbs, confounded and crashed by all the winds, in contention, against each other. Or to the summit of heaven, or to the rapid, awfully great sea, and the fierce, contentious roaring of the four transparent, pure, harsh, directly opposing winds, in the act of breaking loose from the order of their respective positions.
According to the Cogadh, when Brian learned his son Murchadh had drowned while pursuing the enemy into the sea, he cried out, “Oh God! thou boy… retreat becomes us not, and I myself know that I shall not leave this place alive… my body and my soul to God and to Saint Patrick…” In Njal’s saga, it was around this time that “Brodir saw that King Brian’s men were chasing the fleers… he rushed out of the wood, and broke through the shieldburg, and hewed at the king.”
After killing the king, he cried out, “‘Now let man tell man that Brodir felled Brian.’” When Wolf the Quarrelsome, Brian’s brother, heard this, he and some warriors “threw a ring round Brodir and his men, and threw branches of trees upon them, and so Brodir was taken” and met a torturous death. Brodir’s ally for hire, Sigurd, was also slain by Murchadh before drowning. As for Sigtrygg, historian Kerry Cathers notes that “The Cogadh claims that Sitruic remained in Dublin’s walls and watched while his son commanded” the Vikings, but that such an assertion “is likely untrue, though an argument could be made that he remained closer to Dublin in case Brian was successful. Other sources (including Njal’s saga) place him in the thick of battle, taking up the centre position rather than Sigurd…” The Cogadh’s version reads:
And it appeared to the people of Ath Cliath, who were watching them from their battlements, that not more numerous would be the sheaves floating over a great company reaping a field of oats… than the hair flying with the wind from them, cut away by heavy gleaming axes, and by bright flaming swords. Whereupon [Sigtrygg] the son of Amhlaibh, who was on the battlements of his watch tower… said, “Well do the foreigners reap the field… many is the sheaf they let go from them.” “It will be at the end of the day that will be seen,” said Brian’s daughter, namely, the wife of [the son of] Amhlaibh.
In the end, on the side that lost remained the king that married Brian’s daughter. Sigtrygg’s reign as ruler of Dublin lasted nearly five decades until he retired peacefully in 1036 when he no longer wished to rule. Over time, Sigtrygg Silkbeard’s name in Ireland was generally forgotten, but Brian Boru’s lived on.
 James Henthorn Todd, ed., Cogadh Gaedhel re Gallaibh: The War of the Gaedhil with the Gaill, or, The invasions of Ireland by the Danes and other Norsemen (London: Longman, Greens, Reader, and Dyer, 1867), intro cxlviii (148), 191.
 John Ryan, “The Battle of Clontarf.” The Journal of the Royal Society of Antiquaries of Ireland 8, no. 1 (1938), 6. “They burnt Cork, from which the probable conclusion is that Cork was then in Irish, not Norse, hands, though it must be said that the Norse were traditionally unscrupulous in preying upon one another.”
 Dasent, The Story of Burnt Njal (London, New York: Norrœna Society, 1907), 295-296. “She said there were two vikings lying off the west of Man; and that they had thirty ships, and, she went on, ‘they are men of such hardihood that nothing can withstand them. The one’s name is Ospak, and the other’s Brodir. Thou shalt fare to find them, and spare nothing to get them into thy quarrel, whatever price they ask.’” (298)
 Todd, Cogadh Gaedhel re Gallaibh, 153, 175, 179.
 Ibid. 201. “Erinn fell by the death of Brian; and the predictions came to pass, and the prophecies were fulfilled to Erinn, according to the saints and the righteous ones…” (205)
 Dasent, The Story of Burnt Njal, 305-6.
 Kerry Cathers, “Ireland Contested: The Battle of Clontarf, 1014.” Medieval Warfare 4, no. 6 (2014), 46.
 Todd, Cogadh, 191.
About the author
Benjamin J. Swenson has been living and working in Korea since 2008. His doctoral dissertation at Pompeu Fabra University (UPF) in Barcelona, Spain, covered Euro-American military and legal history, and the advent of guerrilla warfare and counterinsurgency doctrine in the nineteenth century. He is currently an Assistant Professor in the Department for Human Creativity at Hoseo University in Asan – where he lives with his wife and son. His hobbies include chess, painting, hiking, and bonsai.