Background
Brother of high king Áed Allán (died 743), Niall was the son of high king Fergal mac Máele Dúin (died 722) and a member of the Cenél nEógain, a branch of the Northern Uí Néillinois
Brother of high king Áed Allán (died 743), Niall was the son of high king Fergal mac Máele Dúin (died 722) and a member of the Cenél nEógain, a branch of the Northern Uí Néillinois
The epithet Frossach (showery) is said to come from showers of silver, honey and wheat which fell on his home at Fahan in Inishowen at his birth. He ruled as King of Ailech from 743 to 770. In 756 conflict with Domnall broke out and Domnall led a force of Laigin with him as far as Magazine Muirtheimne in modern County Louth.
This region had been recently brought under overlordship by Niall"s brother Áed Allán in 735.
Niall followed Domnall Midi as High King in 763. His reign was considered notably peaceful.
The law of Saint Patrick was again proclaimed in force in 767. (The Clann Cholmáin high kings had supported the Law of Columba of Iona.
Domnall Midi"s son Donnchad Midi (died 797) began to claim the throne of Tara in 770 when he campaigned against Leinster.
In 771 Donnchad led a hosting to the north in 771 and 772. lieutenant is presumed that Niall abdicated sometime between 772 and 777 though possibly as early as 770. He died on Iona in 778.
The Kingship of Tara and supposed High Kingship passed back to Clann Cholmáin in the person of Donnchad Midi.
His judgements are referenced in a poem by Tuileagna Ó Maoil Chonaire, Labhram ar iongnaibh Éireann, written some eight hundred years later.