UA BRIAIN, MUIRCHERTACH (1050–1119)Now the dominant figure in Ireland, as king of
Munster and usually overlord of Osraige, Leinster,
Dublin, Mide, and Connacht, Muirchertach neverthe-
less discovered (like his father and his great-grandfather,
Brian Boru) that his authority remained incomplete.
Each year his vast interprovincial army went north
toAssaroe on the Erne or the Sliab Fuaid/Mag
Muirthemhne area on the southeastern frontier of
Ulster, only to be forced back, often following the
intervention of the comarbae Pátraic(the abbot of
Armagh) to secure a year’s truce. In 1100, for exam-
ple, he led “the men of Ireland” to Assaroe to force
Cenél Conaill to submit, simultaneously sending the
Dublin fleet around the coast to Inishowen, but was
forced to retreat, and the fleet was massacred. In 1101,
he was appropriately called for the first time “king of
Ireland” in the Annals of Tigernach, and made his most
spectacular campaign yet, called An Slógadh Timcheall
(the Circular Hosting) by the other annals. The six-
week expedition again involved the armies of all the
provinces, save those of the north, marching to the Erne
at Assaroe, then on to Inishowen, burning en route
Ardstraw and Fahan, and culminating in the demolition
of Grianán of Ailech in revenge for Mac Lochlainn’s
earlier destruction of Kincora. Muirchertach’s men were
ordered to bring back to Limerick one stone for every
sack of provisions they had, and his forces returned
home along the ancient Slige Midlúachra. For the first
time, Ulaid was successfully invaded and its submis-
sion won, making Ua Briain master of all Ireland except
for the northwestern corner which, though under-
mined, had not submitted and never did. Muirchertach
regularly returned, sometimes with disastrous conse-
quences, as in 1103 when (following his possibly con-
scious emulation of Brian Boru in making a donation
of gold to Armagh) his allies were severely routed by
Mac Lochlainn in the battle of Mag Coba; but usually
the annual expedition ended in stalemate in what is
now South Armagh.
In 1101, following his father’s example, he pre-
sided over the Synod of Cashel, which attempted to
reduce lay interference in church affairs, saw Cashel
being handed to the church in perpetuity, and prohib-
ited marriage within specified degrees of consan-
guinity. It was probably at Muirchertach’s behest about
this juncture that the propaganda tract known as
Cogad Gáedel re Gallaib(“The war of the Irish with
the foreigners”) was composed. Combining annalistic
data with romantic embellishments allegedly recount-
ingthe exploits of Brian Boru against his Norse and
other enemies, in fact it uses Brian as a paradigm for
Muirchertach and seeks to glorify his reign. The cul-
mination of the latter was perhaps his institution of
another reform synod at Ráith Bressail in 1111, in
which a formal territorial diocesan structure was
established for the country, and two ecclesiastical
provinces established at Armagh and Cashel, the
former having primacy.
But political opposition remained. In 1112, Domnall
Mac Lochlainn defied him by marching to Dubgaill’s
Bridge in Dublin, raiding Fine Gall, and carrying off
livestock and prisoners. In the same year, Domnall
invaded Ulaid, annexing part of it, which he intended
to rule in person. Muirchertach came to Ulaid in
response, Mac Lochlainn moved his armies to Mag
Coba ready for battle, and the comarbae Pátraicinter-
vened to secure a truce. But the Munster army
remained encamped for a month in Brega, Mac
Lochlainn’s forces observing from the lands of Fir
Rois, County Louth, both prepared for war. Domnall’s
strength is apparent from his refusal to negotiate,
although the crisis was again resolved by intervention
from Armagh.
Muirchertach’s position was weakened further by
opposition from his brother Diarmait and the sons
of Tadc. His own intended heir, his son Domnall,
was proving a disappointment (his nickname ger-
rlámhach(“short-armed”) may indicate a disability).
The convention of apprenticing the heir to Dublin
had been followed, and Domnall managed one major
success in battle there in 1115, but subsequently van-
ished from view and ended his days in monastic
obscurity. Muirchertach fell dangerously ill in 1114
whereuponthe kingship was seized by his brother
Diarmait. When Muirchertach recovered in 1115 and
set about regaining his kingdom, his principal ally was
Brian (d. 1118) son of Murchad (d. 1068) son of
Donnchad mac Briain, his own father’s archenemy.
He needed all the support he could get, since Domnall
Mac Lochlainn reacted to news of the high king’s
illness by forcing the submissions of Ulaid, Mide, and
Bréifne. But, being of similar age to Muirchertach,
his day had passed.
Tairrdelbach Ua Conchobair was the new aspirant
to national power and had invaded Thomond in 1115.
Ua Briain’s problems were eased by the death in that
year of his troublesome nephew Domnall mac Taidc, and
he took to the campaign trail again in Osraige, Leinster,
and Brega, but pressure from Ua Conchobair’s
repeated invasions of Munster finally forced
Muirchertach’s resignation of the kingship of Munster
to his brother Diarmait and his own retirement to
Lismore. When Diarmait died in 1118, Ua Conchobair
partitioned Munster, giving Desmond to Tadc Mac
Carthaig and Thomond, not to Muirchertach’s sons,
but to those of Diarmait. Muirchertach was dead within
a year, the Inisfallen annalist tersely recording his pass-
ing in the words “Murchertach Ua Briain, rí Érend,
fo buaid aithirgi quieuit[Muirchertach Ua Briain, king
of Ireland, rested after a victory of repentance],” the