Moore, Mure, Muir
Moore, Mure, Muir, Moir—These four names are the anglicised forms of the ancient O'More clan in Ulster. The O'Mores formerly occupied a district in S.W. Co. Down, near the Great Wall of Ulster, and they were one of the leading clans of the Pictish nation in Ulster. Some time in the 11th century, at the instance of the Prince of Sth. Leinster, Donal Mac Giolla-Padraic, they went South to his assistance along with the O'Lalors, who occupied the S.E. parts of Down, and McAboys and other Pictish septs; the Munster septs having invaded Leinster. The Pictish septs under the O'Mores, severely defeated the Munster septs, and the O'Mores, with the other septs, settled in Leix. The O'Mores made Disart, near Dunamase, four miles from Port Leix, their head place of residence.
The O'Mores of Co. Kerry are of the same origin.
O'Dugan, the Topographer, refers to the O'Mores as "O'Mordha of the Red Helmits." Melaghlan O'More, son of Lord of Leix, was married to Catherine, daughter of Con O'Neill of Tyrone, and his great-grandson, the famous Rory Og O'More, the founder of the Catholic Defenders, was treacherously assassinated in 1578 by Fitzpatrick of Ossory. The above Melaghlan O'More was grandfather of Rory O'More, father of Rory Og, grandfather of Roger O'More, the founder of the Irish Confederation of 1641, and father of the mother of General Patrick Sarsfield.
The Mures of Ayrshire and Muirs of Dumfries-shire are of Irish origin, the name being common in both counties. The Moores of Cumberland and other parts of the N.W. Counties of England are of the same origin. The Mures of Rowallan, Ayrshire, are descended from Gilchrist Mure, who was given the lands of Rowallan in reward for his service to Alexander, King of Scotland, at the Battle of Largs in 1232. A descendant of this Gilchrist Mure, Sir William Mure, wrote a genealogical history of the Mures, entitled "The Historie and Descent of the House of Rowallane, written by Sir William Mure, Knight of Rowallane, written in, or prior to, 1657." This work was published in Glasgow in 1825, and Sir William Mure distinctly tells us that the Mures came originally from "the ancient Tribe of O'More in Ireland." The Moore's Fort families and those of Moore's Lodge, Co. Antrim, are branches of the O'Moores of Cumberland.
The Moores of Molenan, Co. Derry, and of Garvay House, Aughnacloy, Co. Tyrone, are families of the O'Mures of Ayrshire, of the family of Gilchrist Mure of Rowallan previously referred to.
The Moores of Moore's Hall, County of Mayo, claim descent from the family of Blessed Thomas More, and in the Memoirs of Blessed Thomas More, published in London in 1727, the family is described of the O'Mores who came out of Ireland.
The Moores of the Isle of Man are of the same clan, and the name More was the common form down to the end of the 16th century.
Moore, the Historian of the Isle of Man, who is not ashamed to write his name O'Mordha, says: "The O'Mores were a powerful sept in Ireland."
Jenkin Moore is given as Breive (Breatheamh) or Deemster of the Isle of Man in 1499, in the Manx Statute Law Book.