MAC LOCHLAINN, MUIRCHERTACH (C. 1110–1166)Nevertheless, the Mac Lochlainns did survive in a
very reduced condition in the peninsula of Inishowen.
They remained as chieftains but failed to retain the
lordship, even of Inishowen, which was taken over first
by the Earls of Ulster and then by the powerful Cenél
Conaill dynasty of Ua Dochartaigh. In 1375, Sean Mac
Lochlainn, “Chief of his own tribe” died, and in 1510
“Mac Lochlainn, Uaithne” died. By the end of the
sixteenth century, the Mac Lochlainn chieftains still
survived, tributary to Ua Dochartaigh, and held two
castles on the shore of Lough Foyle. In 1601, Hugh
Carrogh Mac Lochlainn “chief of his sept,” held
Carrickmaquigley Castle (Red Castle) and Brian Óg
Mac Lochlainn held Garnigall Castle (White Castle).
DARREN MCGETTIGAN
References and Further Reading
Byrne, Francis. Irish Kings and High-Kings. London, 1973.
Officio Rotulorum Cancellariae Hiberniae Asservatarum,
Repertorium. Vol. 2, app. 5, Inquisitionum. Donegal.
Ó Corráin, Donncha. Ireland before the Normans. Dublin, 1972.
———. “Prehistoric and Early Christian Ireland.” In The
Oxford Illustrated History of Ireland, edited by R. F. Foster.
Oxford, 1989.
O’Donovan, John, ed. and trans. Annala Rioghachta Eireann,
Annals of the Kingdom of Ireland. Dublin, 1856.
Simms, Katharine. From Kings to Warlords. Bury St. Edmunds,
1987.
———. “Tír Eoghain ‘North of the Mountain.’” In Derry His-
tory and Society, edited by Gerard O’Brien. Dublin, 1999.
The names of all the chief places of strength in O’Doherty’s
country called Inishowen, as well castles as forts, 12 April
1601, SP 63/208PT2/22-25.
See alsoAirgialla; Connacht; Courcey, John de;
Derry; Downpatrick; Dublin; Lacy, Hugh de;
Leinster; Mac Lochlainn; Mellifont; Mide;
Munster; Ua Néill; Tuarastal; Ua Briain; Ua
Conchobair, Ruairí; Ua Conchobair, Tairrdelbach;
Uí Néill, Northern; Ulaid; Ulster, Earldom of
MAC LOCHLAINN, MUIRCHERTACH
(C. 1110–1166)
Muirchertach Mac Lochlainn, son of Niall Mac
Lochlainn (1091–1119), prince of Ailech, was a pow-
erful high king of Ireland. The only event of note
known of his early life was the killing of his father by
the Ua Gairmledaig dynasty of Cenél Móen on 28
December 1119. Thereafter nothing is known of
Muirchertach due to the prominence of his grandfather
Domnall Mac Lochlainn (d. 1121) and his uncle
Conchobar Mac Lochlainn (sl. 1136). Muirchertach
first appears after the killing of Conchobar in 1136 by
Mathgamain Ua Dubda (sl. 1139), lord of Clann
Laithbhertaig, and the men of Mag nItha. Although
Muirchertach succeeded his uncle as over king of
Northern Ireland, he faced challenges, killing Gillamurra
Ua hÓgain that year. In 1139, the king of Ulaid
invaded Muirchertach’s home kingdom of Tír nEógain
to Tullaghoge, plundering the churches in the sur-
rounding plains. Smarting still, Muirchertach then
killed Mathgamain Ua Dubda and the chief men of
his territory. In 1142, he defeated the Uí Dongaile at
Feara Droma, but was severely wounded during that
battle and weakened politically. For in 1143, Domnall
Ua Gairmledaig (sl. 1160) expelled Muirchertach
from Tír nEógain and assumed its kingship. During
1145, Muirchertach returned from what is now
County Donegal with the Cenél Conaill and defeated
Ua Gairmledaig, but failed to depose him. And it took
a second expedition to separate Ua Gairmledaig from
the kingship.
Muirchertach’s return to power had countrywide
significance, leading to the hostages of Leinster’s
being sent “to his house.” His problems with Ulaid
reappeared during 1147 when its king Cú Ulad Ua
Duinnsléibe plundered Fernmag (the modern barony
of Farney, County Monaghan). In response, Muirchert-
ach and his ally Donnchad Ua Cerbaill of Airgialla
(sl.1167) attacked Ulaid and defeated Ua Duinnsléibe
on 29 June, forcing him to surrender hostages. In 1148,
Muirchertach and Ua Cerbaill invaded Ulaid again,
dividing it between four lords. Ua Cerbaill regretted
the removal of Cú Ulad. And with Tigernán Ua Ruairc
of Bréifne (sl. 1172), he restored Cú Ulad in defiance
of Muirchertach, prompting the latter to expel Cú Ulad
and replace him with Donnchad Ua Duinnsléibe.
Before Archbishop Gilla mac Liag (Gelasius) of
Armagh (d. 1173), the situation was resolved tem-
porarily when Ua Cerbaill and the Ulaid gave
Muirchertach hostages. Muirchertach’s tightening grip
over Ulster was displayed later that year when the
Cenél Conaill also gave him hostages, while Ua
Gairmledaig was banished to Connacht. Yet Ulaid
remained a problem. In 1149 Cú Ulad deposed
Donnchad Ua Duinnsléibe, Muirchertach’s protégé,
from the kingship of Ulaid. Muirchertach immediately
invaded, but Ua Cerbaill intervened and gave his own
son as a hostage. Cú Ulad remained recalcitrant, pro-
voking Muirchertach, and after more devastation Cú
Ulad submitted, giving up his own son as a hostage.
The northern king then began his challenge for the
high kingship with a royal progress in autumn 1149,
taking hostages from Ua Ruairc, Murchad Ua
Máelsechlainn of Mide (d. 1153), the men of Tethbae
and the Conmaicní. Muirchertach and Ua Cerbaill
then traveled through Leinster to Dublin, taking the
submission of Diarmait Mac Murchada of Leinster
(d.1171) before making peace between the Leinster
king and the Dublin Ostmen. In 1150, Mac Lochlainn’s
bid for the high kingship received church recognition.