O'NEILL, the name of an Irish family descended from Niall, king of Ireland in the 5th century, and known as Niall of the Nine Hostages. He is said to have made war against rulers in Ireland, Britain and Gaul, stories of his exploits being related in the Book of Leinster and the Book of Ballymote. This king had 14 sons, one of whom was Eoghan (Owen), from whom the O'Neills were descended. The descendants of Niall were divided into two main branches, the northern and the southern Hy Neill, to one or other of which nearly all the high-kings (ard-ri) of Ireland from the 5th to the 12th century belonged ; the descend ants of Eoghan being the chief of the northern Hy Niell'. Eoghan was grandfather of Murkertagh (Muircheartach) (d. 533), said to have been the first Christian king of Ireland, whose mother, Eirc or Erca, became by a subsequent marriage the grandmother of St. Columba. Of this monarch, known as Murkertagh MacNeill (Niall), and sometimes by reference to his mother as Murkertagh Mac Erca, the story is told, illustrating an ancient Celtic custom, that he emphasized the inviolability of a treaty with a tribe in Meath by having it written with the blood of both clans mixed in one vessel. Murkertagh was chief of the great north Irish clan, the Cinel Eoghain, and after becoming king of Ireland in 517, he seized a tract in the modern Co. Derry, which remained till the 17th century in the possession of the Cinel Eoghain. The inauguration stone of the Irish kings, the Lia Fail, or Stone of Destiny, fabled to have been the pillow of the patriarch Jacob when he dreamed of the heavenly ladder, was said to have been presented by Murkertagh to the king of Dalriada, by whom it was conveyed to Dunstaffnage castle in Scotland. (See ScoNE.) A lineal descendant of Murkertagh was Niall Frassach (i.e., of the showers), who became king of Ireland in 763. His grandson, Niall (791-845), drove back the Vikings who began to infest the coast of Donegal. Niall's son, Aedh (Hugh) Finnlaith, was father of Niall Glundubh (i.e., Niall of the black knee), one of the most famous of the early Irish kings, from whom the family surname of the O'Neills was derived. His brother Domhnall (Donnell) was king of Ailech, a district in Donegal and Derry; the ruined masonry of the royal palace is still to be seen on a hill overlooking loughs Foyle and Swilly. On the death of Domhnall in 911 Niall Glundubh became king of Ailech, and, after defeating the kings of Dalriada and Ulidia he became king of Ireland in 915. To him is attributed the revival of the ancient
meeting of Irish clans known as the Fair of Telltown. He fought many battles against the Norsemen, in one of which he was killed in 919 at Kilmashoge, where his place of burial is still to be seen.
His son Murkertagh, who gained a victory over the Norse in 926, is celebrated for his triumphant march round Ireland, the list of these kings will be found in P. W. Joyce's A Social History of Ancient Ireland (London, 1903), vol. i., pp. 7o, 71.
Moirthimchell Eiream, when he captured many kings and chief tains. From the dress of his followers in this expedition he was called "Murkertagh of the Leather Cloaks." The exploit was celebrated by Cormacan, the king's bard, and a number of Murkertagh's other exploits are related in the Book of Leinster. He was killed in battle against the Norse in 943, and was suc ceeded as king of Ailech by his son, Donnell Ua Niall (i.e., O'Neill, grandson of Neill, or Niall, the name O'Neill becoming about this time an hereditary family surname), whose grandson, Flaherty, made a pilgrimage to Rome in 1030.
Aedh (Hugh) O'Neill, chief of the Cinel Eoghain, or lord of Tir-Eoghain (Tir-Owen, Tyrone) at the end of the 12th century, came into conflict with the Anglo-Norman monarchy, whose pretensions he disputed in Ulster. His son (or nephew), Hugh O'Neill, lord of Tyrone, was styled "Head of the liberality and valour of the Irish." Hugh's son, Brian, was inaugurated prince, or lord, of Tyrone in 1291 ; and his son Henry became lord of the Clann Aodha Buidhe (Clanaboy or Clandeboye) early in the 14th century. Henry's son Murkertagh the Strongminded, and his great-grandson Hugh, greatly consolidated the power of the O'Neills. Niall Og O'Neill, one of the four kings of Ireland, ac cepted knighthood from Richard II.; and his son Eoghan for mally acknowledged the supremacy of the English crown, though he afterwards ravaged the Pale, and was inaugurated "the O'Neill" (i.e., chief of the clan) on the death of his kinsman Domhnall Boy O'Neill. He was deposed by his son Henry, who in 1463 was acknowledged as chief of the Irish kings by Henry VII. Contemporary with him was Neill* Mor O'Neill, lord of Clanaboy. From Neill Mor O'Neill's son Brian was descended the branch of the O'Neills who, settling in Por tugal in the 18th century, became Portuguese nobles. This branch represents the male line of the ancient Irish kings of the house of O'Neill.