Diarmait Ua Briain (1060 –1118) was an 11th-century Irish king who ruled

Munster Munster ( gle, an Mhumhain or ) is one of the provinces of Ireland, in the south of Ireland. In early Ireland, the Kingdom of Munster was one of the kingdoms of Gaelic Ireland ruled by a "king of over-kings" ( ga, rí ruirech). Following t ...

from 1114 to 1118. One of three sons of

Toirdelbach Ua Briain Toirdhealbhach Ua Briain (old spelling: Toirdelbach Ua Briain), anglicised ''Turlough O'Brien'' (100914 July 1086), was King of Munster and effectively High King of Ireland. A grandson of Brian Bóruma, Toirdelbach was the son of Tadc mac Briai ...

, he was banished from Munster by his brother

Muirchertach Ua Briain Muircheartach Ua Briain (old spelling: Muirchertach Ua Briain) (also known as Murtaugh O'Brien) (c. 1050 – c. 10 March 1119), son of Toirdelbach Ua Briain and great-grandson of Brian Boru, was King of Munster and later self-declared High King ...

shortly after the death of their father in 1086. He lived in exile for several years while his brother ruled as

King of Munster The kings of Munster ( ga, Rí Mumhan), ruled from the establishment of Munster 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 earliest ...

. He is believed to have been the commander of the Irish fleet that supported

Rhys ap Tewdwr Rhys ap Tewdwr (c. 1040 – 1093) was a king of Deheubarth in Wales and member of the Dinefwr dynasty, a branch descended from Rhodri the Great. He was born in the area which is now Carmarthenshire and died at the battle of Brecon in April ...

at the

Battle of Mynydd Carn The Battle of Mynydd Carn took place in 1081, as part of a dynastic struggle for control of the Welsh kingdoms of Gwynedd and Deheubarth. The result of the battle had a radical effect on the history of Wales. The battle is recorded in the near ...

. In 1093, he reconciled with Muirchertach after recognizing his claim and was installed as ''dux'' of

Waterford "Waterford remains the untaken city" , mapsize = 220px , pushpin_map = Ireland#Europe , pushpin_map_caption = Location within Ireland##Location within Europe , pushpin_relief = 1 , coordinates ...

. He eventually succeeded his brother as acting King of Munster when his brother became seriously ill in 1114. After taking the throne, he banished Muircheartach and soon was involved in a four-year struggle for control of Munster. In 1116, he attacked Muirchertach and Brian Ua Briain ''"in violation of a mutual oath on the relics of Ireland"'' besieging

Limerick Limerick ( ; ga, Luimneach ) is a western city in Ireland situated within County Limerick. It is in the province of Munster and is located in the Mid-West which comprises part of the Southern Region. With a population of 94,192 at the 2016 ...

. This resulted in Muirchertach making peace with Diarmait but he was eventually captured by Muircheartach. He later died in

Cork Cork or CORK may refer to: Materials * Cork (material), an impermeable buoyant plant product ** Cork (plug), a cylindrical or conical object used to seal a container *** Wine cork Places Ireland * Cork (city) ** Metropolitan Cork, also known a ...

in 1118 and in the same year, Toirdelbach Ua Conchobair invaded Munster and partitioned the land between the sons of Diarmait Ua Briain and Tadg Mac Carthaig, Conchobar Ua Briain of

Thomond Thomond (Classical Irish: ; Modern Irish: ), also known as the kingdom of Limerick, was a kingdom of Gaelic Ireland, associated geographically with present-day County Clare and County Limerick, as well as parts of County Tipperary around Nen ...

and Toirdelbach Mac Carthaig of Desmond respectively.

Family

He married Mór Ua Conchobair, daughter of

Ruaidrí Ua Conchobair Ruaidrí mac Tairrdelbach Ua Conchobair (Modern Irish: Ruairí Ó Conchúir; anglicized as Rory O'Conor) ( – 2 December 1198) was King of Connacht from 1156 to 1186, and High King of Ireland from 1166 to 1198. He was the last High King of I ...

anglicised Roderic O'Connor), called Ruaidrí na Saide Buide King of Connacht (died 1118) and had two sons: *Tadc (Tadhg) (died 1154) * Toirdhealbhach (died 1167) He had two other sons by unknown wives or mistresses: * Cochobhar na Cathrach (died 1142) *Donnchad,

Bishop of Killaloe The Bishop of Killaloe ( ) is an episcopal title which takes its name after the town of Killaloe in County Clare, Ireland. In the Roman Catholic Church it remains a separate title, but in the Church of Ireland it has been united with other bi ...

(died 1164) Source: John O'Hart,"Irish Pedigrees or the Origin and Stem of the Irish Nation", Volume 1, 1892, page 157, https://archive.org/stream/irishpedigreesor_01ohar#page/157

References

{{DEFAULTSORT:Ua Briain, Diarmait 1060 births 1118 deaths Kings of Munster 12th-century Irish monarchs Diarmait 11th-century Irish people