Clan O’Byrne of Leinster

A brief history of the O’Byrne clans of Leinster

The Leinster clans of O’Byrne have one of the longest histories of any European family. Their roots are with a royal dynasty, and like all royal dynasties the world over, their origins are rooted in prehistoric mythology. They were rulers of a kingdom, which although on the edge of Europe, was little different in status, power, prestige and ability from the Saxon kingdoms, or the Frankish and Merovingian kingdoms of mainland Europe.

Medieval genealogists, namely monks and scribes, attempted to understand the rise and origin of these dynasties, and to record their histories, joining Labraid, the mythological father of the Leinster dynasty to the legendary ancestry of Milesius of Spain, and in turn connecting Milesius to the biblical Adam and Eve. Now, in a different age, it is possible to follow the minute trails of ancient DNA around the world until it leads back to Africa and a scientific Adam and Eve.

The tribal Uí Dúnlainge established a dynasty in north Leinster by the 6th century. A dynasty that remained in control until Brian Boru of Munster weakened their hold forever. The epic Battle of Clontarf in 1014 and the rise of the Uí Cheinnselaig of south Leinster tumbled the old northern dynasty into chaos and a civil war between the clans of Mac Fáeláin and O’Byrne. Braen, the King of Leinster from whom the clan take their name, died in 1052, but by then his family had already made inroads into what was to become their future homeland in the Wicklow Mountains.

There is a lot of mythology about the Normans driving the O’Byrnes from their native plains of Kildare, but the facts are that they were already in retreat from Kildare before the Normans came, and in the 1170s an alliance with these Normans was more than welcome to an isolated and threatened clan.

The Byrnes’ Country, covering modern Co. Wicklow and beyond, was under the control of two major branches of the clan. The O’Byrnes of Críoch Bhranach were divided into four separate branches of the leading family based at Newrath, while to the south an independent branch of the O’Byrnes (Ranelagh) controlled Gabhal Raghnaill, and to the east another group, the Coulteman O’Byrnes held extensive lands in Carlow from Tullow to Clonmore.

The clan was notably tied to an alliance with the Butler Earls of Ormonde. That is apart from the Ranelagh O’Byrnes who evaded absorption by the Butlers, or by the northern branch of the O’Byrnes, through a close partnership with the Fitzgerald Earls of Kildare. Of course there was a long-standing internal division with the clan highlighted by their conflicting alliances with the opposing Ormond and Kildare power blocs.

Nonetheless, the clan managed to withstand the Dublin administration operating from within the Pale, and to resist, both militarily and diplomatically, the intrusion of Norman baronial, and English governmental power, into its territory. Overshadowing the Kavanaghs, they were undoubtedly the leading clan of Leinster, and led a loose-knit confederation of the Kavanaghs, O’Nolans, O’Moores, and O’Carrolls, even assuming the kingship at times.

Three centuries of warfare appeared to end in 1536 with the collective leadership of the clan coming to terms of peace and mutual acceptance with Henry VIII, entrusting to his over-lordship. However, the corruption of the Tudor administration, with its land-hungry incomers, coupled with an inability to accept the O’Byrnes as true citizens of the Tudor state, led to the rise of the O’Byrnes of Ranelagh. Long the underdogs, they emerged in a bright sunset of Gaelic culture, as protectors of a dying culture, and their mountain fastness of Glenmalure became a refuge of the persecuted, a last bastion of Gaeldom.

Feagh McHugh O’Byrne was a player in international politics, a national hero, and the greatest military genius of the Gaelic military resistance. Although regarded by some within his clan as a usurper, he successfully established himself as its overlord, but his influence, nationally and internationally, was much greater. Overlord of Leinster, the documentary evidence of the Tudor administration regards him as the ‘kingmaker’ behind the O’Neills. Feagh, operating in the shadow of the Dublin administration, and with limited resources, he inflicted upon Elizabeth of England a great military defeat at the Battle of Glenmalure in 1580. Feagh maintained diplomatic relations with Spain and the Papal States, and was the key figure in the Nine Years War. The first leader to be fighting for a united Ireland, and fighting as a European by contrast to Tudor isolation. Yet, his actions were ruthless and controversial in his attempts to bring an end to internal clan conflicts. Surviving poison plots and assassination attempts, Feagh was at last betrayed and killed in May 1597. However, his policies had long been developing along the lines of establishing a national identity, and he showed himself as almost unique among Irish leaders by having objectives beyond the immediate benefit of his own clan. His ideas inspired the Ulster Princes, and his legacy towards a national identity, and a united Ireland, with freedom of conscience, survived his death.

The quatercentenary of Feagh’s death, May 1997, saw a memorial raised to him in the Parnell National Memorial Park, Co. Wicklow. That year also heralded a series of academic lectures that were extended and published by the Rathdrum Historical Society in 1998 as Feagh McHugh O’Byrne. Paul J. Burns published an outline history in 2001, as a guide to researchers, under the title of The Clan O’Byrne of Leinster. Meanwhile the lectures initiated by the Rathdrum Society led to the publication of two major works, Emmett O’Byrne’s War, Politics and the Irish of Leinster (2003), and Christopher Maginn’s Civilizing Gaelic Leinster (2005), both providing excellent in-depth studies.

The seventeenth century saw the leading branches of the Gaelic Leinster O’Byrnes evolve into several prominent Anglo-Irish families
Feagh’s children and grandchildren saw the disintegration of their estates amid a protracted period of English religious and political crisis while at the same time they were dispossessed and displaced from much of their former land holdings in acts of injustice that were later to be cited for their flagrancy by Friedrich Engels. But that was not the end of the story.

Some played the establishment game as members of the Ascendancy; others rose to prominence as nationalists, such as the renowned Garrett and Billy Byrne of Ballymanus and Miles Byrne of Monaseed. At the same time a branch of the clan, the Baronets of Timogue, became elevated in the British peerage as the Barons de Tabley. The fate of this branch of the clan prompted Sir Jonah Barrington to remark that, ‘the family of Byrne, descended from a long line of Irish princes and chieftains, condescended to become little amongst the rank of English commoners’.

Many Byrnes held high military rank or title in the service of Germany, France, the USA, and other countries. Among their numbers were to be found German Barons, French aristocrats, Papal Counts and American pioneers, and their many houses included the French château and the log cabin.

They belonged to a rich and extraordinary brand of Anglo-Irishness best described by Somerville and Ross in Some Experiences of an Irish R.M.

“Mr. Florence (Flurry) McCarthy Knox … was a fair, spare young man, who looked like a stable boy among gentlemen, and a gentleman among stable boys. He belonged to a clan that cropped up in every grade of society in the county, from Sir Valentine Knox of Castle Knox down to the auctioneer Knox, who bore the attractive title of Larry the Liar… I had met him at dinner at Sir Valentine’s, I had heard of him at an illicit auction, held by Larry the Liar, of brandy stolen from a wreck… and all were prepared at any moment of day or night to sell a horse.”

The decline of this society is best expressed by the nineteenth century author, Charles Lever, presented a sadder picture of a fallen native Irish family labouring under British oppression in the preface to his tale of The O’Donoghue .

“Between the great families – the old houses of the land and the present [1872] race of proprietors – there lay a couple of generations of men who, with all the traditions and many of the pretensions of birth and fortune, had really become one in ideas, modes of life, and habits, very little above the peasantry around them. They inhabited it is true, the “great house” and they were in name the owners of the soil; but crippled by debt and overborne by mortgages, they subsisted in a shifty conflict with their creditors, rack-renting their miserable tenants to maintain it. Survivors of everything but pride of family, they stood there like the stumps, blackened and charred, the last remnants of a burnt forest, their proportions attesting the noble growth that had preceded them.”

The story of the Leinster O’Byrnes is also one of emigration. In every continent of the world there have been notable Byrnes.

Recent developments in the study of the history of the O’Byrnes has revealed, as long suspected, that there is not just one clan surnamed Byrne or O’Byrne, but at the very least 12 or more.

An ongoing work is to dispel myths linking the non-Leinster Byrne families to Co. Wicklow and to honour and research their proper backgrounds and histories. This ongoing research is of vital importance to the Leinster clan in order to further clarify and correct the history of the O’Byrnes of Leinster. For instance it was long thought that a branch of the Leinster O’Byrnes settled in Co. Louth, but a re-examination of historical records coupled with DNA studies reveal that the Byrnes of Co. Louth and Monaghan comprise two Byrne clans, related neither to each other nor to the Leinster O’Byrnes. Clarifying the history of the surname is now a vital part of understanding the history of the Byrnes.

Removing Victorian mythology and fiction is another part contribution to a new and better understanding of the story of the O’Byrnes. The demolition of the myth that the Normans drove the clan from Kildare and the recognition that they were already in occupation of parts of Wicklow before the Normans arrived is just one of the new windows throwing light on clan history.

The Leinster Byrnes and the O’Byrnes have made an important and significant contribution to Irish national history, and to world history. It is a fascinating story of how a powerful Gaelic clan emerged from a royal dynasty. Also, of how this clan became revived and re-invented in various branches as Anglo-Irish families and American-Irish families. And yet for all this the history of the O’Byrnes remains something personal and intimate for those researching and preserving the history of their own Byrne family and heritage.


The distinct clans of the O’Byrnes of Leinster are;

1-O’Byrne of Crioch Brannach which is made up of the four houses of

6-O’Byrne of Gabhal Raghnaill (Ranelagh)

To view the official representatives of these houses, please go to our “Guardian of the Name” page.

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