Dictionary of National Biography, 1885-1900/Lughaidh
LUGHAIDH (d. 507), king of Ireland, son of Laeghaire mac Neill, grandson of Niall Naoighiallach and great-grandson of Eochaidh Muighmheadhoin, each of whom was ardrigh of Ireland, became himself ardrigh after the battle of Ocha in Meath in 484, in which his second cousin, Oillioll Molt, king of Ireland, son of King Dathi, son of King Fiachra, brother of Niall Naoighiallach, was slain. Lughaidh was supported in his struggle for Tara by Muircheartach Mac Earca, his cousin, and the most powerful chief in the northern half of Ireland, as well as by the Dal n' Araidhe and some of the Leinstermen. He rewarded the Dal n' Araidhe by a grant of territory to west of their proper boundary, the river Bann, which they continued to hold till the defeat of the Picts in 557. His power as ardrigh was never great; his cousin Muircheartach made war on the Munstermen, and his pagan uncle Cairbre fought the battles of Tailltin, of Sleamhain, and of Cnoc Ailbe against the Leinstermen, while in 497 Muirchearteach attacked Leinster, and in 504 Connaught. In all these wars Lughaidh took no prominent part, and probably only remained king because his nominal suzerainty was useful to Muircheartach. In 507 he was killed by lightning at Achadhfarcha in Meath, and his death is described in a poem ascribed to Gilla Moduba, and extant in several versions (Book of Ballymote, fol. 50 a, 9). The first couplet preserves the genitive case of his name, ‘An Achadhfarcha ughrach Bás mhic Laoghaire Lughach.’
[Book of Ballymote, fol. 50; Leabhar Breac, fol. 14; Annala Rioghachta Eireann, pp. 150–164; Annala Uladh, ed. Hennessy, pp. 26–36; J. O'Donovan's Genealogies, Tribes, and Customs of Hy Fiachrach.]