Brian Boru – Ancestor Of The O’Brien Clan

Brian Boru was born in the first half of the 10th century and died in battle in 1014 in the Battle of Clontarf.

As one of the greatest kings of Ireland, he gave his name to the O’Brien clan and many other variations of the name.

This article takes you through his rise from a lesser kingship in Munster to be the most powerful High King in the land.

Descendants Of Brian Boru

Here are many of the family names that descend from Brian Boru. Are you amongst them?

  • Bryan, Bryant, Bryen, Brian, Brien, Briend, Briens, Brine, Brion
  • O’Bhriain, O’Briain, O’Brian, O’Briant, O’Breen, O’Bryen, O’Bryon, O’Bryan, O’Bryant 
  • MacBrien, MacBryen, McBrian, McBrien, McBryen
  • Ni Bhriain

Our article on how common O’Brien is as an Irish surname shows that it is in the top five names in Ireland.

Kings and High Kings In Ireland

I mentioned that Brian Boru was both a king and a High King of Ireland in his lifetime.

It’s important to understand what this means in an Irish context. It’s very different to the English tradition.

The many kings in Ireland

There were over a one hundred and fifty kings in Ireland in the 10th century. The lesser kings were the chiefs of clans that ruled a local area and tribe.

Thomond would be an example of a kingdom that spanned the two counties of Clare and Limerick. You’ll read later of how Brian became king of Thomond.

A “great king” had the loyalty of several lesser kings.

Kings of the provinces

Above this level were the high kings of the five provinces. The area of Thomond falls within the province of Munster.

When Brian was king of Thomond, he went to battle against the king of Munster.

High Kings

And what about one High King to rule them all? There were no agreed laws in the land that recognized one High King.

That didn’t stop powerful kings from aspiring to be overlords of all the others.

The O’Neills were the most powerful kings on the island from at least the years 500 to 1002.

Many O’Neill kings are broadly considered as High Kings through those centuries until Brian Boru battled to a greater claim to the title.

But let’s not get ahead of the story. Let’s start with Brian’s father and the Dalcassians.

Who Were The Dalcassians?

The Dalcassians (the Dál gCais) were a powerful Gaelic tribe in Munster in the 10th century.

When Cennétig mac Lorcáin became king of the Dál gCais, their base was largely in County Clare by the Shannon River. You can see the county highlighted in pale blue below.

Cennétig led his people in raids further afield. By the time of his death in 950, his domain had expanded to make him King of Thomond.

Cennétig had twelve sons, the youngest of whom was Brian Boru. When Cennetig died, an older son Mathgamain took over the kingship of Thomond.

Brian and Mathgamain were half brothers with different mothers. Brian’s mother was Bé Binn, a daughter of a king in Connacht.

Mathgamain and Brian

It was Mathgamain who captured the Rock of Cashel, the stronghold of the traditional High Kings of Munster. His younger brother Brian campaigned at his side.

Brian’s mother and some of his brothers had been killed in Viking raids out of Limerick (to the south of Clare). He set out for revenge and led raids against Viking forts.

Eventually, Mathgamain joined these efforts. The brothers were successful over the Vikings in the Battle of Sulcoit in 970. After the rout, they plundered and burned Limerick.

Mathgamain was eventually killed by Irish enemies in 976. The forces he defeated to take the Rock of Cashel fought back to retake the stronghold. This rival clan was led by Máel Muad who took the title of King of Munster.

Brian Boru As King Of Munster

Brian took over from his brother as King of Thomond and led his armies to defeat Máel Muad in 978 in the Battle of Belach Lechta.

With Máel Muad dead, Brian was now High King of Munster (although not of the traditional lineage). He went on to rout the last remnants of the Viking army out of the region while allowing Norse traders to remain.

Now that Brian ruled Munster, he turned his attention to the province of Connacht to the north and of Leinster and Meath to the east.

Both provinces were ruled by Máel Sechnaill. he had defeated the King of Dublin in 980, which solidified his power as one of the great O’Neill kings.

Brian and Máel battled each other for supremacy in Leinster for fifteen years.

The Role Of The Shannon

The great river Shannon is the largest river in Ireland. Brian’s father and brother had used ships for raids as well as land forces.

Brian followed their lead to use both the Shannon and the sea in his attacks on Meath and Connacht.

One of his strategies was to use a fleet to attack in location as a diversion. His army would march from another direction to form a pincer movement.

Brian Boru As King Of Leinster

If you’re familiar with Irish geography, you’ll know that Meath is now a county within the province of Leinster.

But back then, Meath was the fifth province of Ireland, with Leinster to the south of it.

Under the pressure of Brian’s armies, Máel Sechnaill met with the King of Munster in 997. The two kings formed a truce.

Máel Sechnaill kept the northern half of the country and ceded authority over the southern half to Brian. This means that Brian had control over Leinster.

However, the Irish clans of Leinster weren’t happy with this arrangement. Their preferred king, Máel Morda, allied with the Viking factions in Dublin to rebel against Brian’s overlordship.

Now, the forces of Meath and Munster came together and went to war against the armies of Leinster and the Dublin Norse. They fought in a tough and bloody battle in the year 999 at Glenmama in County Kildare.

The Leinster armies were routed. Brian marched east to capture Dublin, the port stronghold of the Norse.

Brian and Sitric Silkenbeard

However, the wily king sought a political compromise. He restored Sitric, the former Norse king of Dublin, to his position.

King Sitric Silkenbeard was the son and grandson of two Viking kings of Dublin.

And Brian went a little further than that by striking political marriages. Brian married Sitric’s mother, Gormlaith, and he gave his daughter, Sláine, in marriage to Sitric.

Brian Becomes High King Of Ireland

Although Brian had struck a truce with the King of Meath, he still had bigger ambitions.

Brian marched his armies of Munster, Leinster, and Dublin into battle against Máel Sechnaill and his ally the king of Connacht.

This part of history isn’t recorded in detail. However, the annals say that Mael Sechnaill surrendered to Brian in 1002.

By taking the province of Meath, Brian now claimed the title of High King of Ireland.

However, the kings in Ulster hadn’t yet submitted to his authority.

Despite commanding the forces of the other provinces, it took Brian another ten years to defeat the regional kings of Ulster and gain control of the final province.

Alliance With The Church

Aside from the regional kings, a lot of power in Ireland was in the hands of the Roman Catholic Church through several important monasteries.

The abbots of these monasteries were also members of local clans. They represented a potential threat to Brian’s authority.

So, Brian showed his political prowess once more.

He singled out one of the most powerful churches, the monastery at Armagh. Brian donated a large sum of gold to the Abbott and declared Armagh to be the religious capital of the country.

Why? Well, Brian was better off with the backing of at least one church power base than all of them being against him.

Twelve Years Of Rule By A High King

Brian became High King of Ireland in 1002 and was slain in 1014.

What did those intervening years look like? Later scholars wrote of him as a great king.

It’s hard to disentangle legend from historic reality. But Brian is credited for bringing some stability to the people while building bridges and colleges of learning.

At this stage, he was in his sixties and still engaged in frequent skirmishes and battles with rebellious kings in Leinster and Ulster.

The family connections I already mentioned turned out to be part of his demise.

Family And Rebellion

Máel Morda of Leinster had publicly accepted Brian’s authority but continued to resent his overlordship.

Máel Morda was the brother of Brian’s third wife, Gormlaith. But Gormlaith had been married before to Olaf, a Viking king of Dublin.

I’ve already mentioned Sitric, the son of Gormlaith and Olaf. Brian had restored Sitric to his position of king of Dublin, but Sitric was also feeling rebellious.

Máel Morda and Sitric formed an alliance and assembled Irish and Viking forces in Dublin.

Brian led a force from Munster in 1013 to blockade the city of Dublin. But they ran out of supplies and returned south at Christmas.

The Battle of Clontarf

Máel Morda may have hoped for support from kings in Ulster and Connacht. But although many kings of those provinces didn’t give troops to Brian, they didn’t support Mael Morda either.

Instead, the armies of the former Leinster king were made up of Norsemen, Dubliners, and Leinster men.

Brian’s armies of Munster and Connacht were joined by his old rival and ally Mael Sechnaill mac Domnaill, the king of Meath. He should have outnumbered the Leinster contingent significantly.

However, he fell out once again with Mael Sechnaill, who withdrew his forces.

And then, the Norsemen sailed in from their settlements in Orkney and the Isle of Man. They were in alliance with Sitric of Dublin and were led by Sigurd the Stout of Orkney and Brodir of Man.

Battle commences

The Battle of Clontarf commenced on Good Friday in 1014.

Clontarf was just north of what was then the city of Dublin. The sea is its western border.

The accounts from the time agree that a tough battle raged for a full day. It’s thought that over seven thousand men died on the battlefield.

Battle ends

Toward the end of the day, Brian’s forces were prevailing.

Some of the opposing forces retreated to a wood. I mentioned that Clontarf is on the sea. The tide rises at about 6 pm, and it carried the Viking ships away from shore. It also cut off the men in the wood.

They were trapped by the sea and were set upon by the army led by Murchad, Brian’s son. Those who didn’t drown were killed by sword or spear.

Now, the forces of Norse and Leinster men were routed.

Death Of Brian Boru

Most accounts teach that that Brian was stabbed in the back whilst praying in his tent at Clontarf. There are a few that say he died in battle.

The accounts agree that his killer was Brodir, the Viking from the Isle of Man. But Brodir didn’t get away unharmed. He in turn was killed as he tried to flee the battle.

What of the others?

Máel Morda was killed in battle.

Brian’s son Murchad killed the other Norse leader, Sigurd the Stout.

But Murchad was also killed at the battle, as was his fifteen-year-old son. And of course, many of the opposing kings were also felled.

King Sitric Silkenbeard

Perhaps the wiliest of all these characters was Sitric Silkenbeard, King of Dublin. He didn’t join his fellow Norsemen at the Battle of Clontarf. Instead, he stayed behind to guard the city of Dublin.

Sitric and his wife Sláine watched the battle unfold from the city walls. Sitric reigned long enough to abdicate in 1036. He died some years later in exile.

During that time, he founded Christ Church Cathedral – still standing as a beautiful building in the city.

Where Is Brian Boru Buried?

Brian Boru was taken to be waked at Swords, a place to the north of Dublin city.

From there, a contingent traveled with his body to Armagh in Ulster. It’s said that Brian Boru is buried in the north wall of St Patrick’s Cathedral of Armagh.