Battle of Clontarf The Battle of Clontarf ( ) took place on 23 April 1014 between the forces of Brian Boru and the forces led by the King of Leinster , Máel Mórda mac Murchada : composed mainly of his own men , Viking mercenaries from Dublin and the Orkney Islands led by his cousin Sigtrygg , as well as the one rebellious king from the province of Ulster . It ended in a rout of the Máel Mórda ' s forces , along with the death of Brian , who was killed by a few Norsemen who were fleeing the battle and stumbled upon his tent . After the battle , Ireland returned to a fractious status quo between the many small , separate kingdoms that had existed for some time . Background . Brian Boru ( " Brian mac Cennétig " ( Kennedy ) ) had ruled most of Ireland since 1002 , but the island was still highly fractious and the title of " High King " had been largely ceremonial . Brian looked to change this , and unite the island , which he set about doing over a period of years . In 997 , Brian Boru and Máel Sechnaill mac Domnaill had met in Clonfert and reached an agreement where they recognized each other ' s reign over their respective halves of the country . Brian attacked Máel Sechnaill ' s territory constantly , which forced Máel Sechnaill to resign his land to Brian . In 1012 , the king of Leinster , Máel Mórda mac Murchada , rose in revolt . His attempts were quickly thwarted when Brian arranged a series of cross - marriages , giving his daughter to Sigtrygg Silkbeard , leader of the Dublin Vikings , and himself marrying Sigtrygg ' s mother and Máel Mórda ' s sister , Gormflaith . However this alliance was destined not to last , and in 1013 Máel Mórda again went to Sigtrygg for help after being admonished by Gormflaith for accepting Brian ' s rule . This time Sigtrygg was ready to fight , and various Irish clans who were envious of Brian quickly joined him . Brian immediately imprisoned Gormflaith , and went on a series of raids around Dublin in order to tie down any Irish who would attempt to join the Viking forces . Meanwhile Gormflaith contacted Sigurd Lodvesson , the Viking earl of the Orkney Isles , to come to her aid . He not only agreed , but in turn contacted Brodir of the Isle of Man to join the fight . Sigurd and Brodir both planned on killing the other after the battle to take the seat of High King for themselves , while Sigtrygg was busy trying to form alliances with everyone involved in an attempt to at least retain his own seat in Dublin . In 1014 , Brian ' s army had mustered and set off towards Dublin . As they approached , the Irishmen of Meath , commanded by ex - high king Máel Sechnaill mac Domnaill , refused to take part in the battle . This left him with 4 , 500 men , outnumbering the 1 , 000 or so under Sigtrygg , but considerably worse equipped in comparison . They arrived outside the walls of Dublin and set up camp . That night Brian received news that the Viking forces had boarded their longships and headed out to sea , deserting Sigtrygg . This was in fact a ruse . After nightfall they turned around and landed on the beaches of Clontarf , just over a mile to the north of Dublin , in order to surprise Brian ' s army the next day . At the time Dublin was only on the south shore of the River Liffey , connected to the north bank , and Clontarf , only by a single bridge . This allowed the Vikings time to disembark and prepare in relative safety . Battle . The Viking army formed up into five divisions on the field , while Sigtrygg and 1 , 000 of his men remained in town . Sigtrygg ' s son commanded the extreme left of the line with 1 , 000 of the men from Dublin who decided to fight in the open . Máel Mórda added another 3 , 000 men from Leinster in two divisions . Although numerous , they too were poorly armed in comparison to the Vikings on either side . Sigurd ' s Orkney Vikings manned the centre with 1 , 000 men , and Brodir ' s Vikings added another 1 , 000 or more on the right , on the beaches . Brian ' s forces were arranged in a similar fashion . On the right ( the Viking left ) were 1 , 000 foreign mercenaries and Manx Vikings . Next to them , 1 , 500 clansmen of Connacht were gathered under their kings , while more than 2 , 000 Munster warriors under Brian ' s son Murchad continued the front , flanked by 1 , 400 Dal Caissans on the extreme left led by Murchad ' s 15 - year - old son , Tordhelbach , and Brian ' s brother , Cuduiligh . Off to the right and several hundred yards to the rear stood Máel Sechnaill ' s 1 , 000 men who simply watched . The battle opened with several personal taunts between men in either line , often ending with the two men marching out into the middle of the field to enter personal battle , while the forces on either side cheered . While this went on the two groups slowly edged towards each other . They engaged early in the morning . At first the battle went the Vikings ' way , with their heavier weapons prevailing over their opponents as everyone had expected . This advantage also served Brian , whose Viking mercenaries on his right slowly pushed back the forces facing them . On the left , Brodir himself led the charge and gained ground , until he met the warrior Wolf the Quarrelsome , brother of King Brian . Although Wolf was unable to break Brodir ' s armour , he knocked him to the ground and Brodir fled to hide . This left the now leaderless Viking force facing Murchad ' s forces , who considered themselves the " king ' s own " ( containing many of Brian ' s more distant relatives ) and by the afternoon Brodir ' s forces were fleeing to their ships . In the centre things were going more the Vikings ' way . Both Sigurd ' s and Máel Mórda ' s forces were hammering into the Munster forces . However Sigurd , according to legend , carried a " magical " standard into battle which drew the Irish warriors to it , eventually forcing their way in and killing the bearer . Although the standard was supposed to guarantee a victory for the bearer ' s forces , it also guaranteed the bearer ' s death . No one would pick it up due to its reputation , so Sigurd did and was quickly killed . By the end of the day , after several mutual pauses for rest , the Vikings found themselves with both flanks failing , Sigurd dead , and everyone exhausted . The beaches in front of the ships were already lost , and many men took to trying to swim to the ships further offshore , drowning in the process . The battle was now clearly going Brian ' s way , and the Dublin Vikings decided to flee to the town . At this point Máel Sechnaill decided to re - enter the battle , and cut them off from the bridge . The result was a rout , with every " invading " Viking leader being killed in the battle . Meanwhile Brodir , hiding in the woods near Dublin , noticed Brian praying in his tent . Gathering several followers they ran into the tent and killed him and his retainers . Then they retreated , with Brodir yelling , " Now let man tell man that Brodir felled Brian . " According to Viking accounts , he was eventually tracked , captured and gruesomely killed by Wolf the Quarrelsome with whom he had clashed earlier on the battlefield . Of the 6 , 500 to 7 , 000 Vikings and allied forces , an estimated 6 , 000 , including almost all the leaders , were killed . Irish losses were at least 4 , 000 , including their king and most of his sons . There were in fact some sons of Brian Boru left after the battle of Clontarf . Two of his sons , Donnogh and Teige both were heirs of Brian and after their father ' s death in 1014 , were at debate against each other which started with mild quarrelsome and ended with both brothers coming together in 1018 and killing Donell McDuff Davereann . The two sons of Brian did not inherit the throne right after their father was slain . It was Moyleseachlin ( Irish : Máel Sechnaill mac Domnaill ) - from whom Brian once took power in the heated moment before the Battle of Clontarf - who regained power once again in Ireland . Aftermath . With the Irish now leaderless , and the power of the Dublin Vikings as a political force broken , Ireland soon returned to a series of bloody factional fighting . However things had changed as a result of the battle , with Viking and Gaelic culture no longer contesting power . After a number of years this led to a lasting peace . There were also domestic battles before the 1014 battle , and after the Vikings were supposedly expelled from Ireland , no more written sources state that there were any other fighting between just the Vikings or Norsemen and the Irish . From the " Annals of Clonmacnoise , " “ Moyleseachlin , after King Brian was thus slaine , succeeded again King of Ireland and reigned 8 years , during which time he fought 25 battles both great and small against his enemies . ” His enemies were not the Norsemen , but his fellow Irishmen from other kingdoms . If the Vikings were expelled from Ireland in 1014 , or at least the looting and raiding stopped after that , then whoever the Irish were fighting had to be either another race of people coming into Ireland , just as the Vikings did , or the Irish were having yet another domestic or civil battle . The Battle of Clontarf could have been a domestic battle between kingdoms , and the Vikings were living in and helping out Dublin . The battle could have had other major incentives , but expelling the Vikings might have just given the Irish Munster king ( Boru ) extra motivation to beat the Leinster king . In the source of Clonmacnoise , McMoylenamo is not only the king of Ireland , Wales , and protector of the honor Leah Coynn , but also the “ [ king of the ] Danes of Dublin . ” After the battle in 1014 , Irish high kings actually ruled over the Danes of Ireland ' s five separate kingdoms . Sigtrygg , who had watched the battle with Gormflaith from Dublin , on the south bank of the River Liffey , and with the Irish army melting away the next day , ended up as the only " winner " of the contest , continuing his rule in Dublin until his death in 1042 . The Kingdom of Meath also benefitted from the fact that its warriors suffered few casualties , and managed to come from the battlefield in a much stronger position , with most of its neighbours , including the Dublin Vikings , all incapable of launching further advances . However the series of wars had resulted in a fragmented political landscape , which could not unite under the old High King .