Dictionary of National Biography, 1885-1900/Muircheartach (d.943)
MUIRCHEARTACH (d. 943), king of Ailech, usually known in Irish writings as ‘na gcochall gcroicionn,’ of the leather cloaks, was son of Niall Glundubh [q. v.], king of Ireland, and grandson of Aedh Finnliath, king of Ailech, or Northern Ulster, and of Ireland. He is first mentioned in the chronicles in 921, the year of his father's death, as winning an important battle over Godfrey, a Dane, near the mouth of the river Bann. On 28 Dec. 926, at the head of his own clan, the Cinel Eoghain, and in alliance with the people of the lesser Ulster or Ulidia (Down and Antrim), he defeated a large force of Danes at Droichet Cluna-na-cruimhther, near Newry, co. Down, but was obliged to retire to Tyrone on the arrival of Godfrey of Dublin with a fresh force of Danes. In 927 he defeated and slew Goach, chief of the Cianachta Glinne Gemhin (co. Derry), a rebellious vassal, and then marched south to attack Donnchadh, king of Ireland. No battle took place, as Donnchadh had sufficient notice to get his men together, but Muircheartach boasted that he had for that year prevented the holding of the great fair and games of Teltown. Some years later, in alliance with Donnchadh, he made expeditions against the Danes, and in 938 plundered their territory from Dublin to the river Greece, co. Kildare. Conghalach, son of Maelmithigh, a sarcastic poet, satirised the expedition, and an epigram of Muircheartach's in reply is preserved, beginning 'Cumba Conghalach Breagh mbuidhe ocus duine mut no got' (Annala Rioghachta Eireann, ii. 636). The Danes surprised Ailech in 939 and carried off the king in their fleet on Loch Swilly, but he escaped before they reached the sea. He joined the king of Ireland in 940 in expeditions against Leinster and Munster, and in 941 marched against the Deisi (co. Waterford) and Ossory. He made alliances with both. His wife Flanna, daughter of Donnchadh, the king of Ireland, died in 940, and early in 941 he married Dubhdara, daughter of Ceallach, king of Ossory, and his wife Sadbh.
Muircheartach made a sea-roving expedition to the Hebrides, plundering several Danish settlements in the same year. During his absence Ceallachan [q. v.], king of Cashel, attacked his allies, the Deisi, and this was the occasion of Muircheartach's most famous campaign, known as the 'Moirthimchell Eireann,' or great circuit of Ireland, and described in a poem written in heptasyllabic alliterative verse with vowel rhymes by Cormacan, son of Maolbrighde, his bard, who accompanied the king. The poem was written in 942, and has been printed, with notes, by John O'Donovan (Irish Archaeological Society, 1841). The king, with a carefully selected force of the Cinel Eoghain, left Ailech in the beginning of the winter, crossed the river Bann near Portglenone, marched through Magh Line, and after four days in the kingdom of Uladh, during which they captured the king and Loingseach, the chief of Magh Line, reached the Boyne near Knowth. The next day they crossed Magh Breagh, then covered with snow, and surprised the Danes of Dublin, who did not expect any attack at that season. The Danes gave the king tribute of cloth, gold, meat, and cheese, and a wealthy citizen named Sitric as a hostage. The next day's march was of twenty-one miles to Dunlavin in Wicklow, and from it Aillinn,the chief fort of the king of Leinster, was attacked, and Lorcan, the king, taken as a hostage. To Ballaghmoon, in the south of Kildare, was the next day's march, and on the next day, at Gowran, co. Kilkenny, Muircheartach was hospitably received by his friends of Ossory, and spent some days receiving tribute and entertainment from the chiefs of Ossory, Ely O'Carroll, and the Deisi. He then marched on Cashel, and prepared for a pitched battle, but the Munstermen yielded up their king, Ceallachan, as a hostage and Muircheartach crossed part of the plain south of Limerick, and on the second day reached the Shannon at Killaloe. After several days in Thomond, he turned northwards through Galway and Roscommon, crossed the river Drobhaeis into Ulster, and in three days reached home by way of Bearnasmor, after a month of marching. In the spring Muircheartach sent his captives to Donnchadh, the king of Ireland, in acknowledgment of his supremacy, but the king sent them back to Ailech. His Irish cognomen, 'na gcochall gcroicionn,' was due to the leather mantles which his soldiers wore, and which are often mentioned in Cormacan's account of the circuit. In 943 he was killed in a battle against the Danes at Ardee, co. Louth. He had long yellow hair. He had a son Domhnall, whose son Muircheartach Midheach was killed by Amlaff the Dane in 975. Con Bacach O'Neill, the first earl of Tyrone [q. v.], and Hugh O'Neill, second earl of Tyrone [q. v.], who died in 1616, were directly descended from him. In the 'Book of Leinster,' a manuscript of the twelfth century, there is a poem of fifteen stanzas on his exploits by Flann Mainistrech [q. v.], beginning (f. 184, a. 29) 'assin taltin inbaid oenaig,' and ending (f. 184, a. 52), 'ar tri ced cend leis do ultaib,' with an account of the defeat by Muircheartach of the people of Ulidia, of which there is no other record.
[Book of Leinster (facsimile Royal Irish Academy), a manuscript of the twelfth century; the Circuit of Ireland, by Cormacan Eigeas, ed. J. O'Donovan, Dublin, 1841 (no earlier manuscript exists than a transcript by Cuchoicrich O'Clery of about 1620, but, though the older codices are not extant, this text bears strong internal evidence of authenticity); Annala Rioghachta Eireann, ed. O'Donovan, vol. ii.; Annals of Ulster, ed. W. M. Hennessy, vol. i.]