The ‘Clann Ó Súilleabháin’ is an ancient family. It emerges from the nearly impenetrable mist of prehistory as the ruling class of a small, wandering tribe of warrior Celts, now called the ‘Gaels’. It seems most likely that the tribe originated in the Fertile Crescent, immigrated to the steppes of the Caucasus Mountains, fought and pillaged its way along the shores of the Mediterranean Sea, and finally settled in its own “promised land,” the island of Eire.
According to Milesian tradition, and subsequent genealogical tracts, the Ó Súilleabháin clan rep-resents the most senior bloodline of the Gaelic families. Of the three sons of Milesius  who invaded Ireland and left male issue, Heber Fionn  was the oldest, followed by Heremon and Ir. The southern dynasties of Ó Súilleabháin and McCarthy descended from Heber Fionn . The northern dynasties of O’Neill and O’Donnell descended from the younger brother, Heremon.
After 47 generations of succession, following the principles of primogeniture, Eoghan Mór II , the oldest and favorite son of Oilill Olum  was killed in the Battle of Magh Muchruimhe (Muckrove) near Athenry. He left one son, Fiachaidh Muilleathan .
Eoghan Mór II  was the eponymous progenitor of the Eóghanachta (pronounced Owen-noct-ah), the senior tribe, and royal family, of the Gaelic Celts in Ireland. Fiachaidh Muilleathan  was the common ancestor of both the Ó Súilleabháin and the MhicCárthaigh (McCarthy) clans.
Ten generations passed between Eoghan Mór II  and Fínghin , maintaining the seniority of the line. Fínghin  was the king of Munster circa 600 AD, and leader of the Eóghanacht Chaisil. His descendants become known as the Cenél Fínghin. He was also the last person, of the direct Ó Súilleabháin line, to ever sit on a throne. No one named Ó Súilleabháin has ever been a king. However, the Hereditary Chief of the Clan, ‘The Ó Súilleabháin Mór’, is still properly styled, “Prince of Munster.”
The MhicCárthaigh clan descended from Failbhe Flann, a younger brother of Fínghin . It was at this point that the Eóghanacht tribe split into two major branches, the senior Cenél Fínghin (eventually became known as the Clann Ó Súilleabháin), and the cadet, but regnant, Cenél Failbhe Flann (eventually became known as the Clann MhicCárthaigh).
About 200 years after Fínghin  had reigned over the southern half of Ireland, his great-great-great-great-great-great grandson, Eochaid, assumed the nickname, Súilleabháin (Sullivan) and thus the clan was born.
Fourteen generations followed with the birth of MeicRaith . The oldest son of MeicRaith  was Domhnall , the progenitor of the Sliocht MhicRaith or the Ó Súilleabháin MhicRaith (modernized as the O’Sullivan MacCragh).
When MeicRaith  died, his son, Domhnall , was too young to be elected chief. MeicRaith’s younger brother, Ruairi, assumed the title of chief. Subsequently, the descendants of MeicRaith became known as the Sliocht MhicRaith. The descendants of Ruairi (Sliocht MhicRuairi) maintained the title of An Ó Súilleabháin Mór for several generations, until its extinction in the latter part of the eighteenth century, at which time the title of hereditary chief of the name reverted back to the Sliocht MhicRaith.
Although the Ó Súilleabháin MhicRaith sept enjoyed the rights of seniority through primogeniture, a cadet line of the clan had assumed the title of chief through the machinations of tanistry and the Gaelic laws of succession until its rightful return to the senior line in 1754.
The most senior branch of the Gaelic Nation was the Eóghanachta.
The most senior branch of the Eóghanachta was the Eóghanacht Chaisil.
The most senior branch of the Eóghanacht Chaisil was the Cenél Fínghin.
The most senior branch of the Cenél Fínghin was the Clann Ó Súilleabháin.
The most senior branch of the Clann Ó Súilleabháin was the Ó Súilleabháin Mór.
The most senior branch of the Ó Súilleabháin Mór was the Sliocht MhicRaith.
(Although the Ó Súilleabháin Bheara and Ó Súilleabháin McGillycuddy septs enjoyed a degree of independence from the Ó Súilleabháin Mór Chief, they were both subservient to him by Gaelic law and very much a part of the greater Ó Súilleabháin clan.)
The significance of this can only be appreciated by comparing the status of the old Irish aristocracy with that of the rest of Europe. If the Irish had followed the English system of royal descent by primogeniture, and if Ireland had maintained its independence from England, an Ó SúilleabháinMhicRaith (O’Sullivan MacCragh) would be king of Ireland today.
Due to the peculiarities of the Irish laws of tanistry, however, no Ó Súilleabháin has ever been a king. The use of surnames did not evolve until about the tenth century AD. By then the Ó Súilleabháin clan was subservient to the cadet MhicCárthaigh clan, which was in turn subservient to the non-Eóghanacht Ó Briain (O’Brien) clan.
The Ó Súilleabháin family is the oldest recorded royal bloodline of western civilization. Its noble blood has christened the battlefields of the world for thousands of years. The family has produced paupers and kings, priests and pirates, scientists and wizards. It has fought its many battles with both pen and sword. It has survived the hazards of prehistoric Europe; the Egyptian, Greek and Roman empires; the Dark Ages; the plagues; the Vikings; the Anglo-Normans; the Cromwellian holocaust and its crippling aftermath; the potato famine (An Gorta Mór); and two world wars. The Ó Súilleabháin clan is known for its ability to adapt and it enters the new millennium strong, intact, and poised to regain its ancestral power.
The leather-bound, heirloom version of The Oak and Serpent is now available. It is being sold at cost, with no profit added. Please click on this image to order.
The Oak and Serpent is a 718-page, comprehensive history of the O’Sullivan / Sullivan Clan, from its mythological origin as revealed in the ancient annals, through the Middle Ages, and up to the twenty-first century. A detailed history and genealogy of all the O’Sullivan sub-septs is provided, including the O’Sullivan Beare, the O’Sullivan Mór, the O’Sullivan McGillycuddy, and the O’Sullivan MhicRaith.
The definitive meaning of the name is revealed, as deciphered by Ireland’s leading experts in the Gaelic language. O’Sullivan heraldry is explained, the history of all 32 castles associated with the O’Sullivan clan is reviewed, and several legends peculiar to the O’Sullivan family are presented.
Information concerning the O’Sullivan Clan organization is shared with an invitation for everyone named O’Sullivan or Sullivan to join. The clan tartan, battle flag, song, and flower are discussed, and a thorough Clan Hall of Fame introduces the family’s celebrities.
The O’Sullivan / Sullivan yDNA Project is explained, along with its mission to identify to which O’Sullivan / Sullivan sub-sept everyone with the name belongs. 39 full color plates provide exquisite illustrations of the maps, arms, ancient dress, and regalia of the clan.
The Ó Súilleabháin family is the oldest recorded royal bloodline of western civilization. Its noble blood has christened the battlefields of the world for thousands of years. The family has produced paupers and kings, priests and pirates, and scientists and wizards. It has fought its many battles with both pen and sword. It has survived the hazards of prehistoric Europe; the Egyptian, Greek, and Roman empires; the Dark Ages; the plagues; the Vikings; the Anglo-Normans; the Cromwellian holocaust and its crippling aftermath; the potato famine (An Gorta Mór); and two world wars. The Ó Súilleabháin clan is known for its ability to adapt, and it enters the new millennium strong, intact, and poised to regain its ancestral power.
This heirloom edition is fully bound in rich black leather and embellished with Celtic knot-work gold stamping framing the Seal of Milesius, the official seal of the clan. The raised bands across the spine are distinctive of the classic bookmaker’s art. Colorful end leaves are reminiscent of fine Old-World editions. Coordinating headbands grace both ends of the spine and add strength. The acid-free leaves are smyth-sewn; their edges are gilded for additional protection and elegance. A permanent satin ribbon marker ensures easy reference.
The hard-cover version of the Second Edition of The Oak and Serpent is now available at Book Baby. Please click on image to purchase.
The E-Book version of the Second Edition of The Oak and Serpent is now available at Lulu.com! Please click on image to purchase.