Dictionary of National Biography, 1885-1900/O'Lochlainn, Muircheartach
O'LOCHLAINN, MUIRCHEARTACH (d. 1166), king of Ireland, son of Niall O'Lochlainn, son of Domhnall O'Lochlainn [q. v.], chief of the Cinel Eoghain, was ninth in descent from Domhnall, brother of Niall (870?–919) [q. v.], king of Ireland, from whom, and not from their more remote ancestor, Niall Naighiallach, the O'Neills take their name, according to O'Donovan. His family, who in later times were more often called MacLochlainn, were the senior branch of the Cinel Eoghain, the descendants of Eogfaan, son of Niall Naighiallach. He first appears in the chronicles in 1139, when he defeated the Clann Laithbheartaigh or O'Dubhdas of Ulster, and slew their chief, Mathghamhain. In 1142 he won a battle over the O'Donnellys, a sept of the Cinel Eoghain, in which he received a severe wound. The chiefship of the Cinel Eoghain was assumed in 1143 by Domhnall O'Gairmleadhaigh, the tribe having expelled Muircheartach. He went to the Cinel Conaill, and, with their aid, displaced O'Gairmleadhaigh, and was established as chief of Cinel Eoghain. Cu Uladh MacDuinnsleibhe, king of Ulidia or Lesser Ulster, made a foray in 1147 into Farney, co. Monaghan. Muircheartach O'Neill led the Cinel Eoghain, in alliance with Donnchadh O'Cearbhaill and the Oirghialla, and attacked the Ulidians, whom they found at Uchdearc, co. Down, drove before them to Dundrum, co. Down, and routed in a battle fought on the feast of SS. Peter and Paul, returning with much plunder to Tyrone. He again invaded Ulidia in 1148, and took hostages; but the Oirghiulla, who had marched with him, unexpectedly joined the Ulidians, and he had to retreat. He soon returned, crossing the Ban at Toome Bridge, deposed Culladh, and set up Donnchadh MacDuinnsleibhe as king of Ulidia. Later in the year he attended a convention of the chiefs of the Cinel Eoghain, the Oirghialla, and the Ulidians, who all swore to preserve general peace on a famous relic — the crozier known as the 'bachall iosa' — in the presence of Gilla MacLiag, archbishop of Armagh. The Oirghialla, Cinel Conaill, and Ulidians, all gave him hostages at this time. War, however, broke out in 1149, and he again invaded Ulidia and took many cattle, and received the king's son as a hostage. He went on with all his horsemen to Louth, and there received hostages sent by Tigheaman O'Rourke from Breifne. He next marched to Dublin, and received the submission of the Danes and hostages from Diarmaid MacMurchadha, king of Leinster. In 1150 he gave a gold ring of five ounces and other gifts to Flaibheartach O'Brolchain [q. v.], coarb of Columba, and permitted a general taxation of Cinel Eoghain for the wants of the church of Derry. He marched to Inismochta in Meath, and there received hostages sent to indicate the acknowledgment of his supremacy by Connaught, afterwards going on to Dunlochad, near Tara, where he ratified a treaty of peace with the foreigners of Dublin and Fingall. Turlough O'Brien and Turlough O'Connor [q. v.] were engaged in war, and the Munstermen, under the termer, suffered a disastrous defeat at Moinmor in Munster in 1151. Oljochlainn, taking advantage of this, led the Cinel Eoghain, Cinel Conaill, and Oirghialla across the Erne at Assaroe, co. Donegal, to the Curlew Mountains. Turlough O'Connor, unable to resist such an attack after his long fighting with O'Brien, sent hostages. Next year O'Lochlainn expelled Donnchadh O'Cearbhaill from the kingship of the Oirghialla, in revenge for an insult to the Archbishop of Armagh. He met Turlough O'Connor at the Moy near Ballyshannon, co. Donegal, where they declared amity on the bachall iosa and some relics of St. Columba. They afterwards met at Rathkenny in Meath, and Diarmaid MacMurchadha also came to the meeting. They deprived Tigheaman O'Rourke of Conmhaicne, a country consisting of Longford and the southern part of Leitrim, and divided Meath into east and west, giving the west to Murchadh O'Maeleachlainn, and East Meath to his son Maeleachlainn O'Maeleachlainn. In 1153 he decided to try and restore Turlough O'Brien, and marched to Creeve, co. Westmeath. Tadhg O'Brien, who had displaced Turlough O'Brien, marched thither to attack him, and Turlough O'Connor advanced from Connaught. Muircheartach, with a light division, advanced rapidly and defeated Tadhg O'Brien, then returning to Creeve, and marched with his whole army against Turlough O'Connor. He found Ruaidhri, Turlough's son, pitching his camp at Fardrum, co. Westmeath, attacked him at once and routed his force. Turlough O'Brien was then restored as king of Munster. Turlough O'Connor tried in 1154 to attack O'Lochlainn by sea; but his fleet was defeated off Inishowen, and his commander, O'Dubhda of Connaught, was slain. Muircheartach O'Lochlainn at once invaded Connaught, but was not strong enough to obtain hostages or plunder. He then crossed the Shannon into Breifne and drove out Godfrey O'Reilly, went on to Dublin, was received as king by the Danes, and gave them twelve hundred cows, which he had collected in Meath, to secure their future service in war. In 1155 he made an expedition to Dungolman, co. Westmeath, and took hostages for the territory of Teathbha. He restored to the Meathmen the cattle he had taken from them in the previous year. Turlough O'Connor died in 1156, and this year is considered by the annalists to be the first of Muircheartach O'Lochlainn's reign as king of all Ireland. He was entitled to the succession, being of the royal race, the head of the northern Uí Neill, the descendant of Niall Naighiallach, in the two branches of whose descendants the kingships had rested, in alternate succession, for the six hundred years preceding Brian [q.v.] . The Ulidians attacked him, and he invaded Dalnaraidhe and killed O'Loingsigh the king. He then made a foray into Ossory with Diarmaid MacMurchadha, who had given him hostages. In 1157 he attended a synod at the abbey of Mellifont, co. Louth, at which a papal legate, seventeen bishops, and the Archbishop of Armagh were present. He gave to the abbey 160 cows, sixty ounces of gold, and the lands in Meath called Finnabhair-nan-Inghean. He then marched through Leinster into Desmond, and thence into Thomond, obtaining hostages; took Limerick, and received the submission of the Danes. He returned in triumph, but found that Roderic O'Connor [q.v.] had made a foray into Tyrone in his absence. O'Lochlainn had a quarrel with the Cinel Conaill in 1158, and ravaged their country. About this time he gave a charter and benefaction to the Cistercian abbey of Newry, co. Down. This charter, which has never been accurately printed, though a copy was in the possession of Sir James Ware, styles the king ‘Mauritius MagLachlain Rex totius Hiberniæ.’ In 1159 he led an army to Rubhachonaill, co. Westmeath, and deposed the king of Meath, Diarmait O'Maeleachlainn, and set up his brother Donnchadh O'Maeleachlainn over all Meath. He was threatened by the Connaughtmen, who, with the men of Breifne and of Thomond, crossed Meath to attack the Oirghialla. He came up with them at Ardee, and defeated them with great slaughter. He then marched home, and immediately after ravaged Connaught as far as Tuam, co. Galway. He returned thence by way of Meath, and quartered his army on that country. The sept of his old enemy O'Gairmleadhaigh attacked him in Tyrone after he had, in 1160, induced the chief of Fermanagh to entrap and kill Domhnall O'Gairmleadhaigh and several of the gentlemen of the sept. He defeated them in a pitched battle at Magh Luadhat, near Newtown-Stewart, co. Tyrone, and captured a great booty of cows. He met Roderic O'Connor at Assaroe to arrange a treaty, but none was made. In 1161 he took hostages from the Uí Briuin, and marched through Breifne to Lickbla, co. Westmeath. There Roderic O'Connor and Diarmaid MacMurchadha formally submitted to him, so that he was king of Ireland not only by right, but ‘cen fresabhra’ (‘without opposition’)—a term used by Irish historians to express undisputed sway. In 1162 he aided Flaibheartach O'Brolchain in improving Derry, besieged Dublin, and plundered Fingall. The Danes paid him 120 ounces of gold. He was paid one hundred ounces of gold for the kingdom of Westmeath in 1163. He again aided the Bishop of Derry, and the cathedral was rebuilt in 1164. The Ulidians attacked him in 1165, and he in return ravaged their country, banished Eochaidh MacDuinnsleibhe, their king, burnt their stronghold of Inislachan, and returned with much spoil. He gave to the church of Saul, co. Down, some land which the king of Ulidia handed over to him, with the sword of the son of the earl (probably a Dane) and many jewels. In 1166 he put out the eyes of this king Eochaidh, breaking an oath he had sworn at Armagh after the war. Donnchadh O'Cearbhaill invaded Tyrone to revenge this violation of treaty, and met the Cinel Eoghain in small force at Leitir Luin, near Newtown-Hamilton, co. Armagh. Muircheartach O'Lochlainn was there slain in 1166. He was succeeded by his son Niall.
[Annala Rioghachta Eireann, ed. O'Donovan; Annals of Ulster, 2 vols. (Rolls Ser.); Clarendon MS. in British Museum, xlv. 179; Reeves's Ecclesiastical Antiquities of Down, Connor, and Dromore, Dublin, 1847; O'Donovan's Topographical Poems of O'Dubhagain and O'Huidhrin; O'Flaherty's Ogygia.]