Dictionary of National Biography, 1885-1900/Niall (791-845)
NIALL (791–845), king of Ireland, in Irish annals known as Niall Caille or Cailne, son of Aedh Oirnidhe, king of Ireland, was born in 791, and was seven years old when his father became king of Ireland. Niall (715–778) was his grandfather. He is called Cogadh Gaedhel re Gallaibh in ‘Book of Leinster,’ f. 217 (cf. Annala Rioghachta Eireann, i. 470). In 821 he deposed Murchadh, son of Maelduin, and became chief of the Cinel Eoghain. Eoghan Mainistrech, primate of Armagh, was driven from his see by Cathal, chief of the Oirghialla, in 825, and at once sent his psalm-singer with a complaint in verse to Niall, whose confessor he was. Niall raised the clans of both Tyrone and Tyrconnell, a proof of his great power in the north at the time, and fought a battle with the Oirghialla and the Ulidians near Armagh. He defeated them after a severe contest, and replaced Eoghan in his bishopric. In 833 he succeeded Conchobhar, son of Donnchadh, as king of Ireland. His home was Ailech, near Derry, and when the Danes attempted the plunder of the church of Derry in 833 he met and defeated them. He inherited a feud with the Leinstermen from his father, who had often made war on them, and in 834 invaded Leinster, obtained a tribute, and set up Bran, son of Faelain, as a king in his interest. He also plundered Meath as far as the border of MacCoghlan's country in the present King's County. He made a treaty with Feidhlimidh, son of Criomhthainn, king of Munster, at Cloncurry, co. Kildare, in 837, but in 839 Feidhlimidh tried to become king of Ireland, plundered Meath and encamped at Tara, then, as now, a mere open hill with earthworks. Niall marched from the north, and Feidhlimidh, who had gone to attack Wexford, turned and met him at Maghochtair in Kildare, where he was defeated, and never again attacked Niall. The Danes, who had several times sailed up Lough Swilly in Niall's reign, were caught and defeated by him on Magh Itha, by the river Finn, co. Donegal, in 843. In 845 he was drowned in the River Callan, near Armagh. A cairn, which in 1799 was, in spite of many inroads, still forty-four yards in diameter, was asserted by tradition to be his tomb. A farmer demolished it early in this century. Niall Caille is mentioned in several ancient poems. One of these is put into the mouth of Dachiarog, the patron saint of Erigal Keeroge, co. Tyrone, another into that of Bec Mac De, while a third is attributed to Maenghal Alithir. He is mentioned as an ancestor to be proud of in a poem by Gillabrighde MacConmidhe [q. v.], bard of Brian O'Neill, written in 1260.
His son, Aedh Finnliath, became king of Ireland in 863, and was father of Niall (870?–919) [q. v.] His daughter, who married Conang, king of Magh Bregh, composed a poem on the battle of Cilluandaighri, in which her son Flann was slain (Cogadh Gaedel re Gallaibh, ed. Todd, p. 32).
[Book of Leinster, facs.; Cogadh Gaedel re Gallaibh, ed. Todd; Annala Rioghachta Eireann, ed. O'Donovan; Annals of Ulster, ed. Hennessy, vol. i.; Miscellany of Celtic Society; MacConmidhe's poem, ed. O'Donovan, 1849; Ogygia, R. O'Flaherty, 1685; Stuart's Historical Memoirs of Armagh, Newry, 1819, p. 607, as to his grave.]