Dictionary of National Biography, 1885-1900/Niall (d.1061)
NIALL (d. 1061), king of Ailech, was the younger of the two sons of Maelsechlainn, heir of Ailech, who died in 996, and whose father, Maelruanaidh, slain in 941, and grandfather, Flann, who died in 901, were both in the direct line of succession to the kingship of the north, and were all called ridamhna without ever becoming kings. He raised the tribe known as the Ciannachta of Glengiven, co. Derry, against his brother Lochlainn, who was killed in the battle, and then reigned as king of Ailech. His next war was in 1031 with the Cinel Eoghain. He marched as far as Tullahoge, co. Tyrone, but had to retire without plunder. In 1044 he made a foray into the district of Cuailgne, co. Louth, and carried off twelve hundred cows and many captives. This was a punitive expedition in revenge for the violation of an oath sworn upon the bell of St. Patrick's will. The bell, with an ornate cover or shrine made early in the following century, was preserved by a tribe of hereditary keepers under Niall's protection, and he was thus bound to revenge the insult to its sanctity. In the same cause he made an expedition into Morne, co. Monaghan. He invaded the plain south of the Boyne in 1048, and in 1056 attacked the southern part of Ulidia or Lesser Ulster, now co. Down, and carried off two thousand cows and sixty prisoners. He died in 1061.
[Annala Rioghachta Eireann, ed. O'Donovan, Dublin, 1851, vol. ii.; Annals of Ulster, ed. Hennessy, vol. i. 1887; Reeves's Bell of St. Patrick, Belfast, 1849.]