Annals of Ulster calling him “the tower of the honour
and dignity of the Western World.” All future kings of
Thomond were descended from his brother Diarmait, his
son son Mathgamain being ancestors of the MacMahons
of Corco Baiscind.
S
EÁN
D
UFFY
References and Further Reading
Candon, Anthony. “Muirchertach Ua Briain, Politics, and Naval
Activity in the Irish Sea, 1075 to 1119.” In
Keimelia:
Papers
in Memory of Tom Delaney
, edited by Gearóid Mac Niocaill
and P. F. Wallace, pp. 397–415. Galway, 1988.
Duffy, Seán. “Irishmen and Islesmen in the Kingdoms of Dublin
and Man. 1052–1171,”
Ériu
43 (1992): 93–133.
Duffy, Seán. “The Career of Muirchertach Ua Briain in Con-
text.” In
Ireland and Europe in the Twelfth Century: Reform
and Renewal
, edited by Damian Bracken and Dagmar Ó
Riain-Raedal. Dublin, 2004.
Ó Corráin, Donncha.
Ireland before the Normans
, pp. 142–150.
Dublin, 1972.
Ryan, John. “The O’Briens in Munster after Clontarf.”
North
Munster Antiquarian Journal
2 (1941) 141–152; 3
(1942–43) 1–52, 189–202.
See also
Brian Boru; Cashel, Synod of;
Dál Cais; Munster
UA BRIAIN, TAIRRDELBACH,
(
c.
1009–JULY 14, 1086
AT KINCORA)
Tairrdelbach Ua Briain was king of Munster (1063–1086)
and high king of Ireland (1072–1086). His parents were
Tadc, son of Brian Boru, (d. 1023) and Mor, daughter of
Gilla Brigte hUí Máel Muaid of Cenél Fhiachach.
Tairrdelbach’s early career was dominated by a feud
with his uncle Donnchad mac Briain (d. 1065) who had
incited the Éile to kill Tairrdelbach’s father. Tairrdelbach’s
marriage to an Éile princess named Gormfhlaith was
probably a later peace effort. Tairrdelbach raided his
uncle’s lands in upper County Clare in 1053, and
attacked Donnchad’s son Murchad in 1055. The feud
intensified when Tairrdelbach received support from
his foster-father, the Leinster king Diarmait mac
Máele na mbó. They attacked Donnchad in 1058, who
was forced to burn Limerick to prevent them from
capturing it. In 1062, Tairrdelbach and Diarmait
returned to County Limerick, destroying Donnchad’s
lands and followers. Tairrdelbach was recognized as
king of Munster in 1063.
Tairrdelbach could be ruthless. He preempted rebel-
lion in southwest Ireland by a massive raid in 1064.
Three years later, Tairrdelbach and Diarmait paid Áed
Ua Conchobhair 30 ounces of gold to kill the heir-
designate of Teffa. The following year Tairrdelbach,
Diarmait, and Domnall Ua Gillai Patraic of Ossory
invaded Connacht and provoked a civil war in which
Áed and his brother Conchobar were slain. These unset-
tled conditions sparked a crime wave, and Tairrdelbach
had to proclaim legislation in 1068 forbidding the con-
cealment of livestock.
Tairrdelbach always maintained good relations
with Diarmait. In 1068, Tairrdelbach received gifts
from Diarmait that included his grandfather’s sword
and the standard of the English king Edward the
Confessor. He returned to Leinster again in 1070,
receiving valuables and taking custody of Diarmait’s
troublesome nephew Donnchad mac Domnaill. At
the same time, he imposed his lordship over Ossory.
The death of Diarmait’s sons Glúniairn and Murchad
in 1070 led to a power struggle in Leinster. In 1071,
Tairrdelbach intervened in the conflict between
Diarmait’s grandson Domnall mac Murchada and his
nephew Donnchad. Tairrdelbach afterward imposed
his lordship over Mide, giving the hostages to Diarmait,
and had two bridges built across the Shannon at
Thomond Bridge and Killaloe.
When Diarmait was slain in 1072, Tairrdelbach
promptly asserted his control over Leinster, Mide, and
Dublin. He removed Diarmait’s nephew Donnchad from
Dublin and installed Godred son of Olaf, the uncle of
his daughter-in-law Mór. The next year, two of his kins-
men joined Godred’s brother Sitric for a raid on the Isle
of Man. Family ties were, however, no guarantee of
safety. For reasons that are never stated, Tairrdelbach sent
Godred into exile in 1075. Domnall mac Murchada
briefly seized the kingship, but died before Tairrdelbach
returned and installed his son Muirchertach. The five
Jews who brought gifts to Tairrdelbach in 1079 may have
met him at Dublin.
The final extension of Tairrdelbach’s authority
began in 1073. He led a massive assault on eastern
Mide after his client king Conchobar was slain by
his brother Murchad. He also raided the coast,
despoiling the Gailenga and killing Máelmorda Ua
Cathusaigh of Brega. Tairrdelbach then went into
Connacht and received hostages from Uí Conchobhair
and Breifné. The north was a special concern to
Tairrdelbach, in part because his cousins Conchobar
and Cennetig, sons of Donnchad, had found sanctu-
ary with Cenél nEógain of Tuloch Óg. When the king
of Ulaid, Donn Sléibe Ua hEochada, was deposed
by his kinsman Áed “the furious” in 1078, he sub-
mitted to Tairrdelbach at Kincora. Donn Sléibe was
reinstated as king by 1080. The unfortunate Áed was in
Tairrdelbach’s custody when he drowned at Limerick
in 1083. During all this, Tairrdelbach’s son Diarmait
raided Wales.
Good relations with the church were maintained
by Tairrdelbach. In 1068 he allowed the comarb ofUA BRIAIN, MUIRCHERTACH (1050–1119)