Muirchertach mac Muiredaig (Mac Ercae)

Muirchertach mac Muiredaig (died c. 534), called Mac Ercae, Muirchertach Macc Ercae and Muirchertach mac Ercae, was said to be a High King of Ireland. The Irish annals contain little reliable information on his life, and the surviving record shows signs of retrospective modification. The Aided Muirchertaig Meic Erca takes as its theme the supernatural death of Muirchertach.

According to the genealogies, Muirchertach belonged to the Uí Néill and was the son of Muiredach, son of Eógan, son of Niall of the Nine Hostages; hence Muirchertach mac Muiredaig. His mother, "clearly legendary" according to Thomas Charles-Edwards, was said to be Erc, daughter of "Lodarn, king of Alba". From the matronym comes his alternative name, Muirechertach Macc Ercae. However, Mac Ercae was a common enough male first name. The annalistic entries for Muirchertach span 50 years, from 482 to his death in 534, using various names, including Mac Ercae, so that it is more than likely that two or more people have been confused in the annals.

The first mentions of Muirchertach in the Annals of Ulster, in 482 and 483, associate him, under the name Muirchertach Macc Ercae, with the defeat and killing of Ailill Molt at the battle of Ochae, somewhere in the Irish midlands. One entry names Lugaid mac Lóegairi as his ally there, the other names Fergus Crook-mouth, father of Diarmait mac Cerbaill. In 485, the annals mention the battle of Grainert, perhaps near Castledermot, where Coirpre mac Néill, "or Mac Ercae… as other state", defeated the Leinster king Finnchad mac Garrchon. In 490 or 491, Óengus mac Nad Froích is said to have been killed at the battle of Cell Losnaid, and the second entry reports that "Mac Ercae was the victor". Muirchertach Mac Ercae is said to have won the battle of Inne Mór against the Leinstermen in 498. Many of the entries from the 480s and 490s appear to have been modified, to give Muirchertach the credit for victories won by Coirpre mac Néill and perhaps by Coirpre's son Eochu.

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