The O’Neill dynasty is a group of families that have held prominent positions and titles throughout European history. The O’Neills take their name from Niall Glúndub, an early 10th century High King of Ireland from the Cenél nEógain. Confusion then arises because the Cenél nEógain, descendants of Eógan mac Néill, were a branch of the Uí Néill dynasty who took their name from Niall of the Nine Hostages, a legendary 5th century King of Tara. The Uí Néill were in turn a branch of the Connachta, descendants of the legendary Conn of the Hundred Battles, son of Fedlimid Rechtmar, son of Tuathal Techtma.
The sons of Niall of the Nine Hostages, seven in all, were Conall Gulban, ancestor of the Cenél Conaill dynasty, Éndae, progenitor of the Cenél nÉndai, Eógan mac Néill, ancestor of the Cenél nEógain dynasty, Conall Cremthainne, ancestor of both the Clann Cholmáin and Síl nÁedo Sláine dynasties, Coirpre, ancestor of the Cenél Coirpri, Lóegaire, progenitor of the Cenél Lóegaire, and Fiachu, progenitor the Cenél Fiachach.
Together these dynasties are known to historians as the Uí Néill. They are then divided into the Northern Uí Néill, comprising the first three mentioned above, and the Southern Uí Néill, comprising the remainder. The Cenél nEógain established themselves in western Ulster with their capital at Ailech which centers around what is today known as Innishowen in County Donegal. The Kings of Ailech were often the Northern Uí Néill overkings, who for several centuries rotated as Kings of Tara with the Southern Uí Néill overkings. For most of that period the Tara kingship was rotated exclusively between the dominant Southern Uí Néill Clann Cholmáin and the Northern Uí Néill Cenél nEógain. The system finally broke down in the 10th century.
The O’Neill dynasty is a continuation of the Northern Uí Néill Cenél nEógain dynasty, descendants of the 5th century Eógan mac Néill, through the 10th century Niall Glúndub.
A son of Niall Glúndub was Muirchertach mac Néill, father of Domnall ua Néill, who was the first king to be named High King of Ireland in his obituary. Through Domnall’s grandson Flaithbertach Ua Néill descend the Kings of Tír Eógain, or Tyrone, and the O’Neill dynasty. Most closely related to the O’Neills are the Mac Lochlainns, also of the Cenél nEógain, who in addition to providing two High Kings, Domnall Ua Lochlainn and Muirchertach Mac Lochlainn, also contested the kingship of Tyrone with the O’Neills until the mid-13th century.
Coats of Arms
It is a common misconception that there is one coat of arms associated to everyone of a common surname, when, in fact, a coat of arms is property passed through direct lineage. This means that there are numerous families of O’Neill under various spellings that are related, but because they are not the direct descendants of an O’Neill that owned an armorial device do not have rights or claims to any arms themselves.
The coat of arms of the O’Neills of Ulster, which held the title of High Kings of Ireland, were white with a red left hand cut off below the wrist, and it is because of this prominence that the red hand (though a right hand is used today, rather than the left used by the high kings) has also become a symbol of Ireland, Ulster, Tyrone and other places associated with the ruling family of O’Neills. The red hand by itself has become a symbol of the O’Neill name, such that when other O’Neill family branches were granted or assumed a heraldic achievement, this red hand was often incorporated into the new coat of arms in some way.
The red hand is explained by several slightly differing legends, but which tend to have a common theme that begins with a promise of land to the first man that is able to sail or swim across the sea and touch the shores of Ireland. Many contenders arrive, including a man named O’Neill, who begins to fall behind the other. Using his cunning, O’Neill cuts off his left hand and throws it onto the beach before the other challengers are able to reach shore, thus technically becoming the first of them to touch land and wins all of Ireland as his prize. However, the legends seem to originate in the 17th century, several many centuries after the red hand was already borne by the O’Neill families.