Brian Boru & The Vikings

The Battle of Clontarf – 1014

The Viking Invasion

We all know Brian Boru drove back the Viking invasion in 1014, right? RIGHT? Well done to those who shook their heads. This is a pseudo-history brought forward by Brian Boru’s grandson to boost his family’s name and prestige. The truth is that Vikings were here long before Brian was even born.

Vikings first landed in Ireland somewhere around the year 794 when they started their raids on the island. As time went on, they wondered why they bothered sailing back and forth every year and decided to set up shop. The benefits in trading with the locals, rather than robbing from them, proved profitable and they set up ports in Dublin, Wexford, Waterford, Cork and Limerick. They slowly integrated into Irish lifestyle, inter-married and became allies and enemies to the local kings. There was never a Viking invasion into Ireland. They were assimilated into the country and Irish life continued as normal – which consisted of a lot of wars. It was well over a hundred years before Brian Boru was born.

Who was Brian?

Brian was part of the Dál Cais family. The branch of a branch of a branch of the Kings of Munster. His father, Cennétig (meaning Brian’s name was Brian Mac Cennétig), was at odds with the kings of Munster – mainly the Uí Néill family. And when the Uí Néill’s ascended to the throne of the High King in the 900s they launched war on the Dál Cais, killing two of Cennétig’s sons.

Cennétig died soon after this and his many remaining sons took the mantle. Mathgamin was the most successful of these before Brian, as he managed to take the throne of Munster for the Dál Cais. His victory was short lived, however, as he was captured by an old enemy, Donnubán, and handed over to one of his rivals, Máel Muad, who executed him and took the throne of Munster.

Enter Brian. Mathgamin’s younger brother wasted no time in avenging him. He marched on Limerick and killed Ímar, a Viking leader who had helped scheme the death of Mathgamin. He destroyed Donnubán in battle and then called out Máel Muad to fight him in the hills of the Ballyhoura Mountains in North Cork. Máel Muad accepted the challenge and was destroyed wholly by Brian’s army. The Dál Cais were king of Munster once again and Brian almost immediately started looking at other titles.

I’ve done it! But I need… more.

By this time, Máel Sechnaill of the Clann Cholmáin, was the High King of Ireland. He had taken notice of Brian’s quick ascension to power and was none too pleased when Brian started crossing his borders. Máel marched on the Dál Cais territory and tore up the sacred tree, called a Bile, that Brian’s family used. Brian would have received a Slat na Rige or Rod of Kingship from the sacred tree as this was always given to the new king. The fact that this was the only deed of note recorded of Máel in this attack shows the power and respect shown to arcane and ritual. The tree was simply replanted and Brian crossed the same borders belonging to Máel the following year.

Brian was so successful that by the year 997 he had taken the kingdoms of both Leinster and Munster. Máel Sechnaill had no choice but to form an allegiance with Brian, whereby they split Ireland between them. Brian in the South and Máel in the North. Brian, of course, was only biding his time.


Brian owned all the Viking ports in Ireland at this stage, giving him a huge strategic advantage as the Danes were extremely good in the water. However, before he was to make his move on Máel Sechnaill, he had to quash an uprising by Sitruic Silkenbeard in Dublin. Brian took the city in one of the most important battles of his career and Sitruic fled to Ulster, where he found no protection. He had to come back and submit to Brian and give him hostages. Brian reinstated him as King of Dublin, gave him one of his daughters to marry, and so Sitruic became a vassal. This was three years after the allegiance with Máel Sechnaill was formed and, with this victory in 1000 AD, Brian was ready to leave that allegiance by the wayside and make a bid for the High Kingship.

He did this almost immediately and Máel Sechnaill wasn’t able to raise an army from the kings of his province to fight Brian. So it happened that Máel Sechnaill became a vassal of Brian and remained king of Tara but no longer King of Ireland. Brian now held the title of High King of Ireland. But there was still one province that wasn’t in his power. He turned his attention to Ulster.


Ulster proved to be Brian’s toughest conquest. He went unsuccessful in gaining hostages from the North for quite a long time. In fact, it was 10 years after he gained the high kingship that he finally obtained hostages from Flaithbertach, the strongest opposition in Ulster. It is not known exactly how he did this but it was likely through diplomacy because there is no mention of a battle having taken place. Brian had displayed un-paralleled strength in 1006 when he marched his army around Ireland in a clockwise direction. He brought with him the men of Munster, Connacht, Leinster, Meath and the Norse Foreigners. Such a thing had never been done before and all the annals mention it as something the like of which had never been seen before. He then took this army into Ulster in 1011 and finally became the first and only man to have all the kings of Ireland submit and recognise him as the true High King of All Ireland.

Flaithbertach, and later Cenél Conaill (both of Ulster), didn’t stay quiet for long and started raiding the Kingdoms in the North again. Cenél Conaill launched himself at Connacht and beat their armies, making off with plunder. They did not fear retribution because Brian had to deal with a much bigger problem. This was 1013, the year the Leinster Province went into revolt. The king of Leinster, Brian’s vassal, Máel Mórda was uncle to Sitruic Silkenbeard and he was not happy being subject to Brian. He started stirring trouble and soon had a revolt going. Gormlaith, a previous wife of Brian, was also the sister of Máel Mórda and the aunt of Sitruic Silkenbeard. She is believed to have been a conspirator and helped in stirring up the trouble.

The Battle of Clontarf, 1014

Máel Mórda and Sitruic revolted and Brian laid seige to Dublin in the Winter of 1013. He had to cancel the seige when he ran out of provisions and resolved to return the next year. During this time, Sitruic sent for mercenaries from the islands and was reinforced by Norse steel in 1014. The stage was set for the Battle of Clontarf.

Ultimately, this was Brian’s last fight. The battle that followed was a total victory for his forces but, unfortunately for him, he was found alone on the outskirts of the battle. The story goes that a fleeing Norseman from the battlefield came upon Brian’s tent. Brian was very old – it’s believed he lived to be in his 80s, an amazing age to reach in the times. The Norseman, finding him like this, made swift with his axe and with one clean cut, chopped Brian Boru’s head off.

It is important to point out that the Norse steel were mercenaries called in for their fighting expertise. They were in no way an invading force. Vikings fought on both sides of the battle of Clontarf and continued to live in Ireland, exactly as they had been doing before.

The accounts of the Battle of Clontarf are well documented and if you’re interested in how Brian Boru won the day but lost his life, I recommend Baz Battles’ account of the battle.

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