MAC LOCHLAINN, MUIRCHERTACH (C. 1110–1166)UíFailge, Loígis, and Osraige, forcing their kings to
flee to Connacht. Diarmait Mac Carthaig of Desmond
(sl. 1185) quickly gave him hostages, allowing
Muirchertach to successfully besiege the Ostman
town of Limerick and banish Ua Briain. Before he
marched home, he divided Munster between Mac
Carthaig and Conchobar Ua Briain (bld. 1158). Dur-
ing Muirchertach’s absence in Munster, Ruaidrí
attacked the north, burning Incheny near Strabane,
plundering parts of County Derry and later reversed
the settlement of Munster. There was more trouble in
the north during 1158. Then the Cenél Conaill
revolted, forcing Muirchertach to lead a hosting of
Ulaid and Airgialla to waste Fanad in County Donegal.
In the south, Ruaidrí again threatened, invading Leinster
and taking hostages of Loígis and Osraige. Moreover,
Ruaidrí and his fleet attacked Tír nEógain before
ransacking Tethbae in Mide. His settlement of Mide
was also under pressure from Donnchad Ua
Máelsechlainn. Although defeated by Diarmait Ua
Máelsechlainn and Ua Ruairc, Donnchad significantly
took refuge in Ruaidrí’s Connacht.
During 1159, Muirchertach changed tack in Mide,
banishing Diarmait Ua Máelsechlainn and restoring
Donnchad, causing Ua Ruairc to join Ruaidrí. The
Connacht king now invaded Mide and pushed into Ua
Cerbaill’s Airgialla. Somewhere close to Ardee,
Muirchertach inflicted a massive defeat on the Connacht
army, pursuing Ruaidrí to the Shannon and wasting
Bréifne. After rewarding Donnchad, he returned home
to assemble another army to invade Connacht.
Although Muirchertach sacked the Ua Conchobair
capital at Dunmore, Ruaidrí would not submit, leaving
the high king no alternative but to withdraw. He then
expelled Ua Ruairc from Mide and billeted troops there
presumably to protect Donnchad’s kingship. Pragmat-
ically, Ua Ruairc sued for peace. The high king proved
generous, confirming Bréifne to him. He also con-
firmed Leinster to Mac Murchada, but expelled Mac
Fáeláin, Ruaidrí’s principal supporter, to Connacht. In
spite of such success, Muirchertach faced the reemer-
gence of discord among the subkings of Tír nEógain
during 1160. The principal rebels were Domnall Ua
Gairmledaig, Muirchertach’s old enemy, and Áed Ua
Néill (sl. 1177). Although they enjoyed success,
Muirchertach defeated them near the modern New-
townstuart. He dealt ruthlessly with Ua Gairmledaig,
invading Cenél Móen and having him assassinated,
then dispatching his head to Armagh. However, Mac
Lochlainn’s difficulties and the killing of Donnchad
Ua Máelsechlainn encouraged a resurgent Ruaidrí to
invade Mide, culminating in his giving its kingship to
Diarmait Ua Maelsechlainn. At Assaroe, Muirchertach
met the Connacht king, but they could not agree to a
peace. Muirchertach then marched into Mide to take
its hostages and those of Bréifne, only to be confronted
by the combined armies of Ruaidrí, Diarmait Ua
Máelsechlainn, and Ua Ruairc. Prudently, Muirchertach
avoided battle, allowing Ruaidrí to tighten his hold on
Munster.
Ruaidrí continued to erode the high king’s authority
in 1161. He and Ua Ruairc went into Leinster and took
the hostages of Uí Fáeláin and Uí Failge, leaving
Fáelán Mac Fáeláin and Muirchertach Ua Conchobair
Failge respectively as kings. Muirchertach could not
bridle this usurpation and plundered Bréifne and west
Mide. There Muirchertach took the submissions of the
Dublin Ostmen and Mac Murchada, confirming Leinster
to the latter. Ruaidrí now decided to recognize the high
king as his overlord. Given that the high king did not
interfere with Ruaidrí’s clients in Uí Fáeláin and Uí
Failge, the Connacht king’s submission was far from
unconditional. On the plain of Tethbae, Ruaidrí gave
Muirchertach four hostages for Uí Briúin, Conmaicne,
Munster and Mide, although the annals of Clonmacnoise
say he gave twelve. In return the high king confirmed
Connacht to him. Moreover, Muirchertach granted
half of Mide to Ruaidrí before confirming the other
half to Diarmait Ua Máelsechlainn. At this time,
Muirchertach was king of Ireland without opposition.
Later that year he gave a further demonstration of the
effectiveness of his high kingship, presiding over a
great convention of all the laity and the clergy of
Ireland at Dervor in Meath. During 1162, he brought
an army, including a Connacht contingent, against the
Dublin Ostmen to “take vengeance upon them for his
wife and for her violation.” Although he plundered
Fingal, he could not reduce Dublin before his return
home, leaving Mac Murchada and the Meathmen to
prosecute the siege to a successful end. During 1163,
the Connachtmen repudiated his high kingship, kill-
ing the bodyguard of his son Niall Mac Lochlainn
(sl. 1176) as he feasted in Connacht. That said,
Muirchertach still received a tribute of five score
ounces of gold from the men of west Mide. And in
1164 he and Archbishop Gilla mac Liag of Armagh
prevented the acceptance by Bishop Ua Brolcháin of
Derry of the abbacy of Iona. On the other hand, he
with Ua Brolcháin began to build the great church of
Derry that year. But he was distracted from this work
when the Fer Manach and Uí Fiachrach Arda Sratha
attacked Tír nEógain, quelling them only by killing
the latter’s leader.
The trouble in Ulster during 1164 was nothing com-
pared to that of 1165 to 1166. Then Muirchertach’s
old problem with Ulaid reemerged with a vengeance.
Early that year he deposed Domnall son of Cú Ulad
Ua Duinnsléibe as king of Ulaid, replacing him with
his brother Eochaid Ua Duinnsléibe. This Eochaid was
also Muirchertach’s “gossip” and the foster-son of