The O'Brien dynasty (; ; genitive ''UÃ Bhriain'' ) was an Irish Clan and
noble house of
Munster
Munster ( or ) is the largest of the four provinces of Ireland, located in the south west of the island. In early Ireland, the Kingdom of Munster was one of the kingdoms of Gaelic Ireland ruled by a "king of over-kings" (). Following the Nor ...
, founded in the 10th century by
Brian Boru
Brian Boru (; modern ; 23 April 1014) was the High King of Ireland from 1002 to 1014. He ended the domination of the High King of Ireland, High Kingship of Ireland by the Uà Néill, and is likely responsible for ending Vikings, Viking invasio ...
of the
Dál gCais
The Dalcassians ( ) are a Gaels, Gaelic Irish clan, generally accepted by contemporary scholarship as being a branch of the Déisi Muman, that became very powerful in Ireland during the 10th century. Their genealogies claimed descent from Tál ...
(Dalcassians). After becoming
King of Munster
The kings of Munster () ruled the Kingdom of Munster in Ireland from its establishment during the Irish Iron Age until the High Middle Ages. According to Gaelic traditional history, laid out in works such as the ''Book of Invasions'', the earli ...
, through conquest he established himself as ''Ard Rà na hÉireann'' (
High King of Ireland
High King of Ireland ( ) was a royal title in Gaelic Ireland held by those who had, or who are claimed to have had, lordship over all of Ireland. The title was held by historical kings and was later sometimes assigned anachronously or to leg ...
). Brian's descendants thus carried the name Ó Briain, continuing to rule the
Kingdom of Munster
The Kingdom of Munster () was a kingdom of Gaelic Ireland which existed in the south-west of the island from at least the 1st century BC until 1118. According to traditional Irish history found in the ''Annals of the Four Masters'', the kingdom ...
until the 12th century where their territory had shrunk to the
Kingdom of Thomond which they would hold for just under five centuries.
In total, four Ó Briains ruled in Munster, and two held the High Kingship of Ireland (with opposition). After the partition of Munster into
Thomond and the MacCarthy
Kingdom of Desmond by
Tairrdelbach Ua Conchobair in the 12th century, the dynasty would go on to provide around thirty monarchs of Thomond until 1542.
During part of this period in the late 13th century they had a rivalry with the Norman
de Clare house, disputing the throne of Thomond. The last Ó Briain to reign in Thomond was
Murrough Ó Briain who surrendered his sovereignty to the new
Kingdom of Ireland
The Kingdom of Ireland (; , ) was a dependent territory of Kingdom of England, England and then of Kingdom of Great Britain, Great Britain from 1542 to the end of 1800. It was ruled by the monarchs of England and then List of British monarchs ...
under
Henry VIII
Henry VIII (28 June 149128 January 1547) was King of England from 22 April 1509 until his death in 1547. Henry is known for his Wives of Henry VIII, six marriages and his efforts to have his first marriage (to Catherine of Aragon) annulled. ...
of the
House of Tudor
The House of Tudor ( ) was an English and Welsh dynasty that held the throne of Kingdom of England, England from 1485 to 1603. They descended from the Tudors of Penmynydd, a Welsh noble family, and Catherine of Valois. The Tudor monarchs ruled ...
, becoming instead
Earl of Thomond and maintaining a role in governance.
Throughout the time that the Ó Briains ruled in medieval Ireland, the system of
tanistry was used to decide succession, rather than
primogeniture
Primogeniture () is the right, by law or custom, of the firstborn Legitimacy (family law), legitimate child to inheritance, inherit all or most of their parent's estate (law), estate in preference to shared inheritance among all or some childre ...
used by much of feudal
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
. The system in effect was a dynastic monarchy but
family-elected and
aristocratic
Aristocracy (; ) is a form of government that places power in the hands of a small, privileged ruling class, the aristocrats.
Across Europe, the aristocracy exercised immense economic, political, and social influence. In Western Christian co ...
, in the sense that the royal family chose the most suitable male candidate from close paternal relations—''roydammna'' (those of kingly material) rather than the crown automatically passing to the eldest son. This sometimes led to bitter quarrels and in-family warring. Since 1542, as a part of the
Peerage of Ireland
The peerage of Ireland consists of those Peerage, titles of nobility created by the English monarchs in their capacity as Lordship of Ireland, Lord or Monarchy of Ireland, King of Ireland, or later by monarchs of the United Kingdom of Great B ...
, the head of the Ó Briain house adopted primogeniture to decide succession of noble titles instead.
Naming conventions
Background
The Ó Brian emerged as chiefs of the
Dál gCais
The Dalcassians ( ) are a Gaels, Gaelic Irish clan, generally accepted by contemporary scholarship as being a branch of the Déisi Muman, that became very powerful in Ireland during the 10th century. Their genealogies claimed descent from Tál ...
tribe from the south-west of Ireland and according to historian C. Thomas Cairney, the Dál gCais had come from the tribe of
Erainn who were the second wave of
Celts
The Celts ( , see Names of the Celts#Pronunciation, pronunciation for different usages) or Celtic peoples ( ) were a collection of Indo-European languages, Indo-European peoples. "The Celts, an ancient Indo-European people, reached the apoge ...
to settle in Ireland from about 500 to 100
BC. They were a cohesive set of
septs, related by blood, all claiming descent in tradition from a common ancestor of Cas, sixth in descent from
Cormac Cas.
[O'Dugan, ''The Kings of the Race of Eibhear'', 9.] In the ''
Annals of the Four Masters
The ''Annals of the Kingdom of Ireland'' () or the ''Annals of the Four Masters'' () are chronicles of Middle Ages, medieval Irish history. The entries span from the Genesis flood narrative, Deluge, dated as 2,242 Anno Mundi, years after crea ...
'', the father of Cormac Cas was said to be
Oilioll Olum, who was according to tradition
King of Munster
The kings of Munster () ruled the Kingdom of Munster in Ireland from its establishment during the Irish Iron Age until the High Middle Ages. According to Gaelic traditional history, laid out in works such as the ''Book of Invasions'', the earli ...
and
King of Leinster in the 3rd century.
Such a connection would have meant that the tribe held kinship with the
Eoghanachta, a dynasty who had dominated Munster since the earliest times.
[Duffy, ''Medieval Ireland'', 121.] While founder mythologies were very common in antiquity and the medieval world, such a connection is generally regarded as fanciful and politically motivated in the context of the rise to prominence of the Dalcassians.
Instead, academic histories generally accept the Dalcassians as being the
Déisi Tuaisceart, after adopting a new name — first recorded under their newly adopted name under the year 934 in the ''
Annals of Inisfallen
The ''Annals of Inisfallen'' () are a chronicle of the medieval history of Ireland.
Overview
There are more than 2,500 entries spanning the years between 433 and 1450. The manuscript is thought to have been compiled in 1092, as the chronic ...
''.
The
Déisi
The ''Déisi'' were a social class in Ireland between the ancient and early medieval period. The various peoples listed under the heading ''déis'' shared a similar status in Gaelic Ireland, and had little or no actual kinship, though they were ...
, a people whose name means literally ''vassals'', were originally located where today are south
County Tipperary
County Tipperary () is a Counties of Ireland, county in Republic of Ireland, Ireland. It is in the Provinces of Ireland, province of Munster and the Southern Region, Ireland, Southern Region. The county is named after the town of Tipperary (tow ...
and counties
Waterford
Waterford ( ) is a City status in Ireland, city in County Waterford in the South-East Region, Ireland, south-east of Ireland. It is located within the Provinces of Ireland, province of Munster. The city is situated at the head of Waterford H ...
and
Limerick
Limerick ( ; ) is a city in western Ireland, in County Limerick. It is in the Provinces of Ireland, province of Munster and is in the Mid-West Region, Ireland, Mid-West which comprises part of the Southern Region, Ireland, Southern Region. W ...
;
[Fitzpatrick, ''Royal Inauguration in Gaelic Ireland C. 1100-1600'', 36.] the O'Rahilly's historical model counts them as ethnically
Érainn
The Iverni (, ') were a people of early Ireland first mentioned in Ptolemy's 2nd century ''Geography'' as living in the extreme south-west of the island. He also locates a "city" called Ivernis (, ') in their territory, and observes that this se ...
.
The sept split into the
Déisi Muman who continued to hold territory in Waterford and Tipperary, while the west Déisi controlled areas either side of the
River Shannon.
During the 8th century, the latter was further divided into the Déisi Deiscirt and the Déisi Tuaisceart who would become the Dalcassians.
[Koch, ''Celtic Culture'', 554.] Prehistoric ancestors of the Déisi Tuisceart and Dál gCais may have been a once prominent Érainn people called the
Mairtine
The Mairtine (Martini, Marthene, Muirtine, Maidirdine, Mhairtine) were an important people of late prehistoric Munster, Ireland who by early historical times appear to have completely vanished from the Irish political landscape. They are notable f ...
.
It was during this century that the tribe annexed to Munster the area today known as
Clare and made it their home. Taken from the weakened
UÃ Fiachrach Aidhne it had previously been part of
Connacht
Connacht or Connaught ( ; or ), is the smallest of the four provinces of Ireland, situated in the west of Ireland. Until the ninth century it consisted of several independent major Gaelic kingdoms (Uà Fiachrach, Uà Briúin, Uà Maine, C ...
but was renamed
Thomond (''Tuamhain'', meaning North Munster). After gaining influence over other tribes in the area such as the
Corcu Mruad and
Corcu Baiscinn, the Dalcassians were able to crown
Cennétig mac Lorcáin as
King of Thomond
The kings of Thomond () ruled from the establishment of Thomond during the High Middle Ages, until the Early modern period. Thomond represented the legacy of Brian Bóruma and the High Kings of Ireland of his line who could not hold onto all of ...
, he died in 951.
His son
Mathgamain mac Cennétig was to expand their territory further according to the ''
Annals of Ulster
The ''Annals of Ulster'' () are annals of History of Ireland, medieval Ireland. The entries span the years from 431 AD to 1540 AD. The entries up to 1489 AD were compiled in the late 15th century by the scribe Ruaidhrà Ó Luin� ...
''; capturing the
Rock of Cashel
The Rock of Cashel ( ), also known as Cashel of the Kings and St. Patrick's Rock, is a historical site located dramatically above a plain at Cashel, County Tipperary, Cashel, County Tipperary, Republic of Ireland, Ireland.
History
According t ...
capital of the Eoghanachta, the Dalcassians became
Kings of Cashel and Munster over their previous overlords for the first time in history.
Mathgamain along with his younger brother
Brian Boru
Brian Boru (; modern ; 23 April 1014) was the High King of Ireland from 1002 to 1014. He ended the domination of the High King of Ireland, High Kingship of Ireland by the Uà Néill, and is likely responsible for ending Vikings, Viking invasio ...
began military campaigns such as the
Battle of Sulcoit, against the
Norse Vikings of the settlement
Limerick
Limerick ( ; ) is a city in western Ireland, in County Limerick. It is in the Provinces of Ireland, province of Munster and is in the Mid-West Region, Ireland, Mid-West which comprises part of the Southern Region, Ireland, Southern Region. W ...
, ruled by
Ivar. The Dalcassians were successful, plundering spoils of jewels, gold and silver, saddles, finding "soft, youthful, bright girls, booming silk-clad women and active well-formed boys".
[Frances Cusack, ''Ireland'', 294.] The males fit for war were executed at Saingel, while the rest were taken as slaves.
Through much of his reign Mathgamain was competing with his Eoghanachta rival
Máel Muad mac Brain.
Mathgamain was only defeated in the end by a piece of treachery; he believed he was attending a friendly meeting, but was betrayed at
Donnubán mac Cathail's house, handed over to his enemies and executed in 976. The crown of Munster was briefly back in the hands of the Eoghanachta for two years until Brian Boru had thoroughly avenged his brother, with the defeat and slaying of Máel Muad in the
Battle of Belach Lechta.
Rise of Brian Boru
The following year Brian came to blows with the Norsemen of Limerick at
Scattery Island where a monastery was located. Whilst all parties were
Christians
A Christian () is a person who follows or adheres to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. Christians form the largest religious community in the world. The words '' Christ'' and ''C ...
, when their king Ivar and his sons took refuge in the monastery, Brian desecrated it and killed them in the
sanctuary
A sanctuary, in its original meaning, is a sacred space, sacred place, such as a shrine, protected by ecclesiastical immunity. By the use of such places as a haven, by extension the term has come to be used for any place of safety. This seconda ...
; the Vikings of Limerick had earlier killed Brian's mother.
Following this the Dalcassians came into conflict with those responsible for the death of Mathgamain, the Eoghanachta represented by Donovan and Molloy. A message was sent to Molloy, where Boru's son Murrough would challenge him in single combat; eventually the Battle of Belach Lechta took place where Molloy along with 1200 of his soldiers were slain. Donovan was destroyed together with Aralt, his brother-in-law and Ivar's remaining son, newly elected king of the Danes and Foreigners of Munster, in Donovan's fortress of Cathair Cuan, which Brian razed. With this Brian Boru was now the
King of Munster
The kings of Munster () ruled the Kingdom of Munster in Ireland from its establishment during the Irish Iron Age until the High Middle Ages. According to Gaelic traditional history, laid out in works such as the ''Book of Invasions'', the earli ...
.
Brian's rise did not go unnoticed, however;
Máel Sechnaill II from the
Clann Cholmáin sept of the
Uà Néill
The Uà Néill (; meaning "descendants of Niall") are Irish dynasties that claim descent from Niall NoÃgÃallach (Niall of the Nine Hostages), a historical King of Tara who is believed to have died around c. 405. They are generally divided ...
, as reigning
king of Mide and
High King of Ireland
High King of Ireland ( ) was a royal title in Gaelic Ireland held by those who had, or who are claimed to have had, lordship over all of Ireland. The title was held by historical kings and was later sometimes assigned anachronously or to leg ...
marched an army down to Munster to send a warning to the Dalcassians. His army cut down the tree of ''Magh Adhair'', which was sacred to the Dalcassians as it was used as their site of royal inaugurations. This sparked a conflict between Máel Sechnaill and Brian, the object of both men to be recognised as High King.
A treaty would eventually be reached between Máel Sechnaill and Brian which split the areas of influence in Ireland between them. Brian gained control over a large portion of the island's south including Dublin. The peace didn't last long as Brian used the newly acquired forces of Dublin and Leinster to spearhead an attack against Máel Sechnaill which ended in their defeat and forced Brian to reconsider pressing any further North.
The war dragged on but Brian would eventually force Máel Sechnaill to accept his authority when northern branch of the Uà Néill clan refused to support him. Despite his fall in position Máel Sechnaill would become one of Brian's most important allies. Eventually the northern Uà Néill branch would accept Brian's rule as well, unusually for the time this was done peacefully, their submission to Brian was negotiated by the clergy rather than forced in battle.
With the most powerful Kings in Ireland now accepting Brian as the High King it was a much easier task for Brian to force the remaining Kings to submit to his rule and though it may have been tenuous he eventually was acknowledged as High King by all the rulers in Ireland.
[Bryne, ''Irish Kings and High Kings'',]
O'Brien dynasty
Brian's descendants, the Ua Briain provided a further three
High Kings of Ireland and exercised supremacy in
Munster
Munster ( or ) is the largest of the four provinces of Ireland, located in the south west of the island. In early Ireland, the Kingdom of Munster was one of the kingdoms of Gaelic Ireland ruled by a "king of over-kings" (). Following the Nor ...
until
Tairrdelbach Ua Conchobair, taking advantage of war between brothers
Diarmait and former High-King
Muircheartach, invaded
Munster
Munster ( or ) is the largest of the four provinces of Ireland, located in the south west of the island. In early Ireland, the Kingdom of Munster was one of the kingdoms of Gaelic Ireland ruled by a "king of over-kings" (). Following the Nor ...
and split it in two in the
Treaty of Glanmire (1118) granting
Thomond to the sons of
Diarmait Ua Briain and
Desmond to the leading sept of the dispossessed
Eoganacht, the
Mac Cárthaigh dynasty. After the death of
Domnall Mór Ua Briain, a claimant to the Kingship of Munster, they further retreated beyond the
Shannon into the area of modern
County Clare
County Clare () is a Counties of Ireland, county in the Provinces of Ireland, province of Munster in the Southern Region, Ireland, Southern part of Republic of Ireland, Ireland, bordered on the west by the Atlantic Ocean. Clare County Council ...
in the wake of the
Norman Invasion. In 1276
King Edward II granted all of Thomond to
Thomas de Clare, taking advantage of the feuding between Clann Taidhg and Clann Briain (whom de Clare supported). The de Clares failed in conquering Thomond, and were decisively defeated in the
Battle of Dysert O'Dea in 1318, thus the
Kingdom of Thomond remained outside of foreign control for a further 200 years.
[The Normans in Thomond, Joe Power http://www.clarelibrary.ie/eolas/coclare/history/norman.htm ]
In 1543
Murchadh Carrach Ó Briain agreed to
surrender his
Gaelic Royalty to
King Henry VIII
Henry VIII (28 June 149128 January 1547) was King of England from 22 April 1509 until his death in 1547. Henry is known for his six marriages and his efforts to have his first marriage (to Catherine of Aragon) annulled. His disagreement w ...
and accepted the titles
Earl of Thomond and
Baron Inchiquin. At his death in 1551 the Earldom passed to his nephew
Donough by special remainder, and the title
Baron Inchiquin passed to his male heirs through his son
Dermot. The Earldom went extinct at the death of
Henry O'Brien, 8th Earl of Thomond; the next heir would have been a descendant of
Daniel O'Brien, 3rd Viscount Clare who had been
attainded in 1691, so the title became
forfeit. However,
Charles O'Brien, 6th Viscount Clare, a
Jacobite exile used the title Earl of Thomond, as did his son, who died childless in 1774. At the death of
James O'Brien, 3rd Marquess of Thomond, the title
Baron Inchiquin passed to a distant cousin and descendant of
Murrough,
Sir Lucius O'Brien, 5th Baronet, and was passed down to his descendants.
Family tree
Key:
*

=
King of Dál gCais
*

=
King of Thomond
The kings of Thomond () ruled from the establishment of Thomond during the High Middle Ages, until the Early modern period. Thomond represented the legacy of Brian Bóruma and the High Kings of Ireland of his line who could not hold onto all of ...
*

=
Baron Inchiquin
*

=
Viscount Clare
*

=
Earl of Thomond,
Earl of Inchiquin
*

=
Marquess of Thomond
Notes
See also
*
Irish nobility
*
Irish royal families
*
List of people named O'Brien
*
Irish clans
Irish clans are traditional kinship groups sharing a common surname and heritage and existing in a lineage-based society, originating prior to the 17th century. A clan (or in Irish, plural ) included the chief and his Patrilineality, patrilineal ...
References
Footnotes
Bibliography
*
*
*
*
*
*
*
*
*
*
External links
The O'Brien Clan
{{DEFAULTSORT:Obrien Dynasty
Septs of the Dál gCais
Aibell
O'Brien
Gaels