DC782 Brian Boru DNA

By Peter Biggins
About PetersPioneers

Dennis Wright, Dennis O'Brien, Leo O'Brien, and Maureen O'Brien contributed to this study.

DNA helix R-DC782 seems to be the Y-DNA of Brian Boru, king of Thomond, who died in 1014. In 2022, Family Tree DNA very roughly estimated that DC782 was born around 900 AD.

A present-day Y-DNA tester, Conor Myles John O'Brien, has a detailed pedigree back to Brian Boru. He is kit 29355. His Y-DNA goes back to a mutation named DC782. Many other testers named O'Brien go back to that same nutation. He lives in Thomond House near Dromoland Castle in County Clare

My son's uncle-in-law, Leo O'Brien, has this Y-DNA. He is kit 197598. He descends from Michael O'Brien, born in 1815 in Doneraile, County Cork, about 90 miles south of Dromoland Castle, County Clare, the home of Conor Myles John O'Brien.

There is similarity between a set of seven names in the ancient genealogy of Brian Boru and a set of seven names among Y-DNA testers with R-FGC5659 Y-DNA. born around 650 AD.

The Irish Type III Website      L226 DNA Project      O'Brien DNA Project      About PetersPioneers      Home Page

Table of Contents

Two Matching Sets of Seven Names

The identification of Brian Boru DNA rests upon the similarity between a set of seven names in the ancient genealogy of Brian Boru and a set of seven names among 88 of 160 testers with R-FGC5659 Y-DNA., born around 650 AD.

Surnames in the Ancient Genealogy of Brian BoruFTDNA Testers as of March 2021
SNP SurnameN88 FTDNA Kit Numbers
O'Brien, King of Thomond, O'Hart 154FGC5659 O'Brien55176989, 107307, 48596, MK43540, 45897, IN49258, 822032, 62268, 606858, B234890, 74637, MK37301, MK37299, B288126, 29355, 477041, N142662, IN32215, B96372, IN73613, 259847, 603927, B224950, 206478, 548647, 730949, 935473, 58280, IN85607, B240961, IN73006, IN54774, 938272, B3546, 30225, 286323, 171533, 197598, 345292, 460890, B447669, 656407, B122229, 368920, 505175, 52082, 326033, 717257, 154119, 281586, B385305, B183643, AM15749, 40468, 416203
O'Kennedy, Chiefs in Ormond, O'Hart 98, O'Hart 156, and O'Hart 227DC709 Kennedy12344136, 728240, IN26076, 302019, 740921, 405921, 422354, 438505, 688850, B162155, xxxxx, 401109
O'Casey, O'Hart 156FGC5647 Casey8844322, 77349, 51924, 920824, 539983, 93773, B3986, B89528
O'Dea, Chiefs of Dysart O'Dea, County Clare, O'Hart 191DC1344 O'Dea4IN11528, IN33914, 313937, 363020
Hearne of Thomond, O'Hart 156DC38 Ahern4MK44600, B3470, 537546, 878206
O'Lynch of Thomond, O'Hart 101 and O'Hart 233BY4103 Lynch3930638, 311627, xxxxx
MacMahon, Lords of Corca Baisgin, County Clare, O'Hart 148BY4103 McMahon2293008, 110326

Many people with Brian Boru DNA do not have historical surnames. The major names are: Kelly, Lindsey, Luttrell, and Morrissey. Brian Boru DNA has not yet been found for some historical Brian Boru names.

Abridged Brian Boru Big Y SNP Tree

R-M269     4350 BC     Southern Russia
P312     2800 BC     Southern Germany     "Celtic"
L21     2600 BC     Southern England
Z253     2350 BC     Northen England
L226     Munster     250 AD
FGC5660     300 AD

91. Cas b. 347 AD

Z17669     450 AD
ZZ31     500 AD
FGC5628     550 AD
FGC5623     600 AD
FGC5659     650 AD
850 AD

ZZ34     800 AD
1250 AD

1400 AD

1050 AD

850 AD

DC782     900 AD

105. Brian Boru 940-1014 AD
106. Teige d. 1022 AD
107. Turlough 1099-1086 AD
950 AD

Y5610     1050 AD

108. Dermod d. 1120 AD

117. Brian d. 1399 AD
1000 AD

1400 AD

FT129209     1400 AD

118, Turlough d. 1459 AD

135. Conor Myles John O'Brien b. 1943 AD

SNPs: SNPs, e.g., DC782, are single nucleotide polymorphisms, or mutations, found on the Y chromosome and shared by a group of testers. Major SNPs are shown in the first row of the table. SNPs between L226 and Brian Boru are shown in the second row.
Conor Myles John O'Brien Ancestry: Selected generations from Cas to Brian Boru down to Conor Myles John O'Brien, kit 29355, are interspersed with his SNPs. See: 45 Generations: Cas to Brian Boru to O'Brien.
Surnames: Surnames with three or more testers are listed under the SNPs. Surnames in bold are said in ancient pedigrees to be descended from Brian Boru. Some surnames in the ancient pedigrees are not here because they have not been tested, died out, or were included in a pedigree in error. Also, surnames have multiple origins, even within a clan. The most populous name is O'Brien.
*Includes Leo O'Brien, kit 197598, my son's uncle-in-law.


My interest in DC782 Brian Boru DNA stems from the marriage of our son into an O'Brien family. Their family genealogist Maureen O'Brien traces their heritage back to Michael O'Brien, who was born in Doneraile in 1815. Doneraile is in County Cork, about 90 miles south of Dromoland Castle in County Clare, the home of Conor Myles John O'Brien who traces his ancestry back to Brian Boru. Maureen's father Leo O'Brien, kit 197598, has this DNA. He matches men with a set of surnames that correspond to a set of surnames descended from the Dalcassian tribe, which is traced back to 3rd century Ireland. The most illustrious Dalcassian was Brian Boru, Brian Bóruma mac Cennétig, who was born around 940 AD in County Clare, Ireland. He was killed at the Battle of Clontarf on April 23, 1014.

In April 2006, Ken Nordtvedt identified a unique DNA of a group of testers with Irish ancestry centred on the counties of Clare, Limerick and Tipperary. One of the people who had this DNA was Dennis Wright. It was the third unique Irish DNA to be identified, so Dennis called it Irish Type III DNA. In December 2006, he started The Irish Type III Website.

In Spring 2009, Dennis Wright had a paper published in the Journal of Genetic Genealogy entitled "A Set of Distinctive Marker Values Defines a Y-STR Signature for Gaelic Dalcassian Families" that concluded the following.

Analysis of 25-marker short tandem repeat haplotypes in the Ysearch database reveals a distinctive Y-DNA signature that peaks in frequency in the Irish counties of Tipperary, Clare and Limerick. These counties were the hereditary homelands of the Dál gCais families, also called Dalcassian, septs descended from Cas, born CE 347, sixth in descent from Cormac Cas, King of Munster. Dalcassian surnames are more strongly represented with this signature than other surnames.
In November 2009, the SNP L226 was discovered at Family Tree DNA. L226 is also called Irish Type III.

Conor Myles John O'Brien traces his ancestry back to Brian Boru. He tested his Y-DNA at Family Tree DNA in 2004. His kit is 29355. He eventually confirmed that DC782 was the SNP of Brian Boru.

Table of Contents     

Brian Boru (940-1014)

The Clare County Library has provided the following description of Brian Boru (c. 940-1014).

Brian Boru was born around 940, the youngest of two sons of Cennedig, head of Dal Cais, one of the royal free tribes of Munster. Brian grew up during the worst days of tyranny when the Dalcassians had been driven in to the present county of Clare. Brian’s brother, Mahon, being the eldest, succeeded Cennedig as chief of the Dalcassians. Being hemmed into Clare by the Norse Leader, Ivar of Limerick, Mahon was willing to accept terms but Brian, seeing almost all of the Dal Cais tribe including his mother brutally murdered by a Norse raid when he was only a child, refused to be any part of such a truce. He deserted Mahon with a group of soldiers. They lived in the hills of Munster attacking Norse settlements and disappearing in to the hills. His fame spread throughout the province and infuriated Ivar. Although having only a handful of men, Brian’s skill as a tactician led him to defeat vastly superior numerical forces and led to rumours of a mighty Dalcassian army.
After a number of petty battles, Brian had trained an excellent Dalcassian army to face the Norsemen. The stories of his triumphs had led to vast numbers of young men volunteering to join his side. The feud between himself and Mahon ended. Mahon renounced his truce with the Norsemen and the two brothers rejoined forces. The two men triumphed so far that Mahon took the throne of Cashel in 963 and in 968 at Sulchoid in Tipperary, the two brothers completely overtook Ivar’s forces and marched on Limerick while Ivar fled back to the Norse lands. The Norse tyranny in Munster thus collapsed and Mahon ruled peacefully for eight years. However, Ivar returned to Ireland and plotted the murder of Mahon. After Mahon’s death, Brian not wanting a bloodbath between his forces and Ivar’s, honourably challenged Ivar to open combat, which he won killing Ivar. Brian succeeded his brother as head of the Dal Cais and immediately took the field against his brothers enemies. In 978, he defeated the King of Cashel in battle. Step by step he established himself in the Kingship of Munster and fortified the province. In 983 and 988, his fleets ravaged Connaught and plundered Meath.
Meanwhile, another great leader had arisen in the North, Malachy the second, the Ui Neill King of Tara. Malachy was born in 948, became King of Meath and in 980, High King. This he achieved at the battle of Tara in 980 where he overthrew a Norse Army and took Dublin. A clash between the two men was inevitable. At last, in 998, they met and divided Ireland between the two of them, Brian becoming the King of the South and Malachy of the North.
By 1002, the joint sway of Malachy and Brian could not last. Malachy, being unable to gather enough support to take on the mighty forces of Brian, allowed Brian peacefully to take over his lands. This was the greatest moment in the history of native Ireland. Brian, by his title, “Ard Ri”, was claiming the monarchy of the whole Gaelic race. Before Brian, and Malachy, Ireland was divided in to a number of petty kingdoms, sometimes at peace, sometimes at war with one another. The Vikings themselves joined in the struggles between the Irish kingdoms and also fought bitterly among themselves. There was no one king up to this who was responsible for the defence of Ireland against the Vikings and had control over the entire island.
Brian had much to do as High King to lift Ireland out of the ruins of the Norse Age. He rebuilt ruined churches, built others, he sent overseas to replace lost books and artefacts and all that he possibly could to heal the wounds of the past two centuries of Norse pillage.
In 1013, the Leinstermen and the Dublin Vikings revolted against Brian. Mael Morda, King of Leinster, allied himself with the Dublin Vikings and went to war with Brian. The Dublin Vikings sought allies overseas. The great sigurd, Earl of Orkney, came with a large contingent. While other Viking contingents came from as far afield as Iceland and Normandy. Brian gave them Battle at Clontarf on Good Friday, 1014 and defeated them. However, as the Vikings were retreating, one of their leaders, Bothair, murdered Brian.
After this, Malachy resumed his position as High King and the Dal Cais strength remained only in Munster. The Viking presence in Ireland continued after Brian’s death but their military power was crushed. They remained in the country as traders and intermarried amongst the native Irish. Ireland was never again to have a King to control the entire of the island and the cost to Ireland and to Brian of crushing the Viking power in this country was a great one, for Ireland was never again to have a true “ARD RI”.
Bloody Acre
Bloody Acre, where Brian Boru was killed in 1014. South of the Tokla River in northwest corner of what is today Glasnevin Cemetery, two miles north of the Dublin city center. Source: Ordnance Survey Ireland.

Table of Contents     

45 Generations: Cas to Brian Boru to Conor O'Brien 29355

Conor Myles John O'Brien, who was born in 1943 and lives in Thomond House near Dromoland Castle in County Clare. He traces his ancestry back to Brian Boru, who is No. 105 in the pedigree shown below. He has had his DNA tested at Family Tree DNA and is O'Brien 29355, with the SNP DC782 (900 AD). See the Results pages of: L226 DNA Project and O'Brien DNA Project. He shares the SNP DC782 (900 AD) with over 50 other O'Briens, all of whom are likely to be descendants of Brian Boru. According to Dennis Wright at Irish Type III DNA, Conor Myles John O'Brien has impeccable credentials.

The pedigree back to Generation 91, Cas, is from two sources.

  • John O'Hart's 1892 Irish Pedigrees
    • Generations 91 (Cas) to 104: "O'Brien (No. 1) King of Thomond," pages 154-162
    • Generations 105 (Brian Boru) to 120: "O'Brien (No. 1) King of Thomond," pages 154-162
    • Generation 121: "O'Brien (No. 2) Marquises of Thomond," page 163
    • Generations 122 to 131: "O'Brien (No. 5) Barons and Earls of Inchiquin," pages 169-170
  • Burke's Peerage
    • Generation 132: Edward Donough O'Brien, 14th Baron of Inchiquin (M, #17941)
    • Generation 133: Lucius William O'Brien, 15th Baron of Inchiquin (M, #28636)
    • Generation 134: Hon. Fionn Myles Maryons O'Brien (M, #484007)
    • Generation 135: Conor Myles John O'Brien, 18th Baron of Inchiquin (M, #484010)

Google Books has made the 1892 edition available online: Volume I and Volume II. The University of Pittsburgh Library System has made the 1892 edition available online as a PDF file or Ebook: Volume I and Volume II. Library Ireland has made a transcript of Volume I available online.

O'Hart's 1892 Irish Pedigrees includes 12 ancient names with pedigrees related with Brian Boru. Modern-day people with these same names have been found to have the same DNA--what we call L226 and Brian Boru DNA. Many of these names appear on pages 154-162 of Vol. I, O'Hart, which give the Brian Boru pedigree back to Cas, from whom comes the name "Dalcassians."

Burke's Peerage refers to Peerage, Baronetage & Knightage, Charles Mosley, editor, 2003. Darryl Lundy, from Ngaio, Wellington, New Zealand, has put Burke's Peerage online at The Peerage. Link's to Burke's Peerage here are to Lundy's The Peerage.

Generations 120 to 131 are available from Burke's Peerage (The Peerage) as well as O'Hart's 1892 Irish Pedigrees.

45 Generations: Cas to Brian Boru to Conor O'Brien 29355

Interspersed with the Y-DNA mutations, called SNPs (single nucleotide polymorphisms), of Conor Myles John O'Brien.

Generations 91 to 120: O'Hart's 1892 Irish Pedigrees, "O'Brien (No. 1) King of Thomond," pages 154-162

    FGC5660     300 AD

  1. Cas: a quo the Dal Cais or "Dalcassians;" b. 347. Had twelve sons:—1. Blad, 2. Caisin, 3. Lughaidh, 4. Seana, 5. Aengus Cinathrach, 6. Carthann Fionn, 7. Cainioch, 8. Aengus Cinaithin, 9. Aodh, 10. Nae, 11. Loisgeann, and 12. Dealbheath
  2. Blad ("bladair:" Irish, to coax; Lat. "blater-o," to flatter): the eldest son of Cas; a quo O'Bladair, anglicised Blair, Flattery, and Blood (of Munster); b. 388; left four sons:—1. Carthann Fionn Oge Mór; 2. Carthann Dubh; 3. Eochaidh; 4. Brennan Ban, ancestor of O'Brennan (of Thomond), Glinn, Glynn, Maglin, Magan, Muldowney (now "Downey"), O'Hurley, etc. (see also O'Dea, Chiefs of Dysart O'Dea, County Clare, O'Hart 191 and MacNamara, Lords of Dunratty, County Clare, O'Hart 150)
  3. Carthann Fionn Oge Mór: eldest son of Blad. Had two sons: 1. Eochaidh Ball-dearg; 2. Aengus, who was the progenitor of O'Curry, O'Cormacan, O'Seasnain, etc. (see also O'Lynch of Thomond, O'Hart 101 and O'Hart 233)
  4. Eochaidh Ball-dearg: son of Carthann Fionn Oge Mór. Received Baptism at the hands of St. Patrick, and d. at an advanced age, leaving two sons: 1. Conall, 2. Breacan, a quo "Ibrickan," a barony in the county Clare
  5. Conall: the elder son. Died vita patris, and left issue: 1. Aodh Caomh; 2. Molua Lobhar, or St. Molua the Leper, founder of the church of Killaloe, co. Clare
  6. Aodh Caomh ("caomh:" Irish, gentle; Arab, "kom," noble; Lat. "com-is"): the elder son; a quo O'Caoimh, anglicised Coombe. Was King of Cashel. Of him Lodge says: "He was the first Christian King of this family, that became King of all Munster; and his investure with the authority and title of King of that Province was performed at his own Court, in the presence of St. Breanan of Clonfert, and of his domestic poet MacLemein, who afterwards became first bishop of Cloyne; and also by the concurrence of Aodh Dubh, son of Criomthan, then chief representative of the Eugenian race." He had two sons: 1. Cathal; 2. Congall, the ancestor of O'Noonan, of Thomond and South Connaught (see also O'Neill of County Clare, O'Hart 242)
  7. Cathal: the elder son
  8. Turlogh: his son; b. 641. Had—1. Maithan; 2. Ailgeanan, who was the ancestor of O'Meara, Scanlan and MacArthur
  9. Maithan: son of Turlogh; b. 683
  10. Anluan: his son
  11. Corc: his son
  12. Lachtna: his son. Had his residence at a place called Grinan Lachtna, near Killaloe: he d. at an advanced age
  13. Lorcan (also called Fingin): his son; was King of the Dalcassians; d. 942. Had three sons:— 1. Cineidi; 2. Cosgrach, the ancestor of Cosgrave of (Munster), and O'Hogan; 3. Lonargan, a quo Lonergan; 4. Congal; 5. Bran Fionn, a quo Slioght Branfionn, in Wexford: a sept who took the permanent sirname of O'Brien, from this Bran, when sirnames were introduced into Ireland
  14. Cineadh (or Cineidi), King of Thomond: the son of Lorcan; m. Babhion, dau. of Arcadh, son of Murrough O'Flaherty, lord of Iar Connacht or West Connaught (see also O'Hogan, Chiefs of Crioch Cian, O'Hart 96, O'Hart 156, and O'Hart 220)

    DC782     900 AD

  15. Brian Boroimhe, the 175th Monarch of Ireland: a younger son of Cineadh; b. 926, at Kincora, the royal seat of his ancestors; and fell by the hand of Brodar, the Danish admiral, at the Battle of Clontarf, on Good Friday, the 23rd April, 1014, in the 88th year of his age. This Brian ("Brian:" Irish, very great strength), was the ancestor of O'Brien, Kings of Thomond. He had eleven brothers, of whom only four left issue, viz.— 1. Mahoun, the eldest brother, who was King of Munster, before Brian, and a quo many families. II. Donchuan, who was the ancestor of, among other families, Eustace, O'Kennedy, O'Regan, (of Thomond), O'Kelleher, O'Beollan (or "Boland"), O'Casey, Power, Twomey, etc. III. Eichtigern (a quo Ahearne, Hearne, Heron), who was ancestor of MacCraith, (or MacGrath), of Thomond, etc. IV. Anluan, who was the ancestor of Quirk, etc. (see also O'Kennedy, Chiefs in Ormond, O'Hart 98, O'Hart 156, and O'Hart 227)

    Brian Boroimhe was four times m.; his first wife was Mór (more), dau. of Flan O'Hyne, Prince of Hy-Fiachra Aidhne, in Galway, by whom he had three sons of whom Murrough, who fell at the Battle of Clontarf, was one. Brian was secondly m. to Eachraidh, dau. of Ceaibhall, son of Olioll Fionn, and had:
    • 1. Teige;
    • 2. Donal, who distinguished himself at Clontarf, and was slain by the Siol Murray in a battle fought by the Dalcassians against the Conacians.
    His third wife was Gormliath, the "Kormloda" of Icelandic history; sister of Maolmora, King of Leinster: and relict of Aulaf, the Danish King of Dublin, to whom she bore the celebrated Sitric, who succeeded his father as King of the Danes of Dublin. By Gormliath Brian had Donogh, the 176th Monarch of Ireland, who was the ancestor of Plunkett, and of the O'Briens of Coonagh, in Limerick, and of Aherlow, in Tipperary; and a daughter Sabh, who m. Cian, who is No. 109 on the "O'Mahony" pedigree, by by whom she had Mathgabhuin, the founder of the family of O'Mahony, in the county Cork. Brian's fourth wife was Dubhcobhla, who d. s. p. 1009; she was dau. of Cathal O'Connor, King of Connaught
  16. Teige: younger son of Brian Boroimhe; m. Mór, dau. of Gilla-Brighid O'Mulloy, Lord of Fircall, in the King's County. (Another authority gives Mór as being the dau. of Melaghlin, son of Maolmora the 51st Christian King of Leinster). Teige was killed in 1022 by his brother Donogh, who thus became King of Munster. Donogh was m. to Driella, dau. of Godwin, Earl of Kent, and sister of Harold II., the last Saxon King of England; after a reign of forty-nine years Donogh abdicated; went on a pilgrimage to Rome, and took the habit of a Monk in the monastery of St. Stephen where he soon after died
  17. Turlogh Mór (d. in 1086, aged 77 years), became King of North Munster on the abdication of his uncle Donogh; m. Mór, the dau. of O'Hyne, of Kilmacduagh, in the co. Galway, by whom he had four sons and a daughter. The sons were—1. Teige, who d. at Kincora, leaving two sons, Murrogh and Daniel. 2. Murtogh, who succeeded his father; carried fire and sword, in A.D. 1101, through Conacht and Tir Conal; marched to Aileach Neid which he burned; and after a reign of 30 years he retired (1116) to the monastery of Lismore to repent of his sins—especially of his violation of the sacred soil of Aileach; he died at Lismore in 1119, leaving: Donal, the Shorthand (whose sons Connor and Lewy fell in battle in 1151); Mahon, ancestor of MacMahon of Corca Bascin, and Cineidi Ochar. 3. Dermod, of whom presently. 4. Donogh, slain in 1103 at the battle of Magh Coba. And the dau. was Mór, who m. Roderic O'Connor the 183rd Monarch of Ireland (see also MacMahon, Lords of Corca Baisgin, County Clare, O'Hart 148)

    Y5610     1050 AD

  18. Dermod: son of Turlogh Mór; in 1116 succeeded his brother, Murtogh, as King of North Munster; m. Sadhbh, dau. of Teige MacCarthy Mór, Prince of Desmond (see "MacCarthy Mór" pedigree, No. 108), by whom he had issue—two sons, 1. Connor-na-Catharach, and 2. Turlogh. The Princess Sadhbh, on the death of Dermod, m. her cousin Cormac Magh-Tamnagh MacCarthy Mór. Dermod, in 1116, was defeated by the Hy-Niall and their Conacht relatives at Ruadh-Bheithach, near Dunkellin, co. Galway; he d. in A.D. 1120, was interred in Killaloe, and was succeeded by his son Connor, who, dying in 1142, was succeeded by his brother, Turloch
  19. Turlogh: son of Dermod; became King of North Munster in 1142; he m. twice—first, to a dau. of MacCarthy Mór, who d. s. p.; and secondly, to Narait or Ragnait, the dau. of O'Fogarty, lord of Ely-Deisceart (or Eliogarty), in Tipperary, by whom he had five sons: —1. Donal Mór; 2. Murtogh, who d. s. p.; 3. Brian of the Mountain, lord of Ormond;. 4. Dermod; 5. Consaidin or Constantine ("Saidh:" Irish, mildness, gentleness; "in," little), bishop of Killaloe (d. 1194), ancestor of the MacConsidine of the co. Clare, Teige, uncle of Turlogh, contended with him for the Sovereignty of Munster, and a bloody battle was fought at Cluan-na-Catha, near Ardfinan, in Tipperary, in which Teige was defeated. In the year after, another terrible battle was also fought between Turlogh and Teige and his allies, at Barrymore in Cork, in which Teige was again defeated; upwards of seven thousand fell on both sides, A.D. 1152, Turlogh, after a reign of 25 years, died and was interred at Killaloe, 7th Nov., 1167, leaving his son Murtogh King of Munster, who was slain in 1168, by the people of Clare, at the instigation of Connor O'Brien; for which his brother Donal, on his accession, fined them 3,000 cows
  20. Donal Mór (d. 1194): son of Turlogh; the last King of North Munster; was m. to Orlacan, dau. of Dermod na Gall MacMorough (by his wife, the dau. of O'Moore, Prince of Leix), and had Mór, who married Cathal Craobh Dearg O'Connor (d. 1224), the 51st Christian King of Conacht, with nine sons: 1. Donogh Cairbreach; 2. Murtogh Dall, ancestor of the Clan Murtogh Dall O'Brien, of Hy-Bloid, in the northeast of the co. Clare; 3. Connor Ruadh; 4. Murtogh Fionn, ancestor of the Clan Turlogh Fionn of the same territory; 6. Donal Conachtach, ancestor of Clan Donal Conaghtaigh, of Echtge, and subsequently of Ara, in the county Tipperary; 7. Brian (surnamed "of Burren"), ancestor of Clan Bhriain Boirnigh; 8. Connor, ancestor of Clan Connor Guasanaigh; 9. Dermod Fiodhnuich, ancestor of the Clan Dermod Fiodhniagh. In 1169, this Donal Mór founded a religious house, afterwards the cathedral church on the site of the existing edifice in Cashel; in 1171, he founded a nunnery in the City of Limerick, but not a vestige of it remains. In 1172, following the example of Dermod MacCarthy Mór, King of South Munster, he made Henry II., King of England, a tender of his submission on the banks of the Suir:—
    "Woe worth that hour, woe worth that day,
    That cost the freedom of the Gael;
    And shame to those who broke the trust,
    In them reposed by Inis Fail."
    In 1175, Donal, blinded Dermod, son of Teige O'Brien, and Mahon, son of Turlogh, his kinsmen, which act caused the death of Dermod soon after at Castleconnell. In 1176, Donal expelled the Anglo-Normans from the City of Limerick, putting most of Henry II's garrison to the sword. In 1192, he drove the English out of Upper Ormond, Ara, and Coonagh, where they established themselves; and stripping them of the booty they took from the native chieftains
  21. Donogh Cairbreach O'Brien: eldest son of Donal Mór; d. 1242. Was the first of the family that assumed this sirname, and the title of "Prince." Was surnamed "Cairbreach," from his having been nurtured in Hy-Cairbre-Aobha. He erected the palace of Clonroad, near the town of Ennis, and m. Sabia, dau. of Donogh O'Kennedy, lord of Muscry Tire, by whom he had Sabina (who married Geoffrey O'Donoughue of Killarney), and six sons: 1. Connor; 2. Turlogh; 3. Murtogh; 4. Dermod; 5. Teige Dall; 6. A daughter Slainé, who d. Abbess of Killowen, in the barony of Islands, co. Clare—the foundation of her father in 1190. This Donogh Cairbreach O'Brien founded the abbeys of Corcomroe, in the barony of Burren, co. Clare; Killcooley, in the parish of Slievearadh, county Tipperary; Galbally, in the parish of Galbally, barony of Costlea, co. Limerick; and the Franciscan Monastery at Ennis, co. Clare
  22. Connor-na-Siuddine: eldest son of Donogh; slain at the Wood of Siudan, in Burren, county Clare, in 1268: hence the epithet affixed to his name, and a quo Sidney. He m. Mór, dau. of MacNamara, lord of Hy-Coileann, and left issue: 1. Teige; 2. Brian Ruadh, ancestor of O'Brien of Arra; 3. Murtogh, who died without legitimate male issue
  23. Teige (d. 1259): the son of Connor; surnamed Caol Uisge: so called from his having (see No. 113 on the "O'Neill," Princes of Tyrone pedigree) attended there to hold a conference with Brian Catha Duin O'Neill, to whom this Teige O'Brien and Hugh O'Connor "granted the sovereignty over the Irish," in 1258, or constituted him Monarch of Ireland. This Teige m. Finola, dau. of Kennedy, son of Kennedy, son of Murtogh O'Brien, and had: 1. Turlogh Mór; 2. Donal, who defeated Mahon, grandson of Donal Conachtach, at the Abbey of Clare, in 1276
  24. Turlogh Mór, the hero of MacGrath's "Wars of Thomond:" the son of Teige; d. at his residence Insi-an-Lasi in 1306. Was m. three times: first, to Sabina (d. s. p.), dau. of Teige MacCarthy, of Dun-Mac-Tomain; secondly, to Orflath, (or Aurnia), dau. of Donal Oge MacCarthy Mór, by whom he had— 1. Brian (ancestor of Siol Bhriain na Geall, of Glen Cean), 2. Murtogh (founder of the houses of Thomond and Inchiquin), 3. Dermod (who left no issue); and the third marriage of Turlogh was to Sabina O'Kennedy, of Muscry Tir, by whom he had two sons—1. Connor, and 2. Donal
  25. Murtogh: second son of Turlogh Mór; d. 1343. Was twice m.: first, to Sarah (d. s. p.) dau. of O'Kennedy, of Ormond; and, secondly, to Edaoin or Edina, dau, of his standard bearer, MacGorman, of Ibrackan, by whom he had three sons: 1. Maithan; 2. Turlogh Maol, ancestor of O'Brien of Bun-Cumeragh, in the county Waterford; 3. Teige
  26. Maithan Maonmaighe, who d. 1369: the son of Murtogh. The epithet applied to him means that he was fostered in "Maonmaighe," near Loughrea. Was m. to Winifred, dau. of O'Connor Corc., by whom he had seven sons: 1. Brian; 2. Connor (who m. Mary, dau. of Teige O'Brien, lord of Coonagh, by whom he had—1. Dermod; 2, Donal, bishop of Limerick; 3. Brian Dubh, the progenitor of O'Brien of Carrigagunnel and Glin, in the county Limerick); 3. Teige Baccach, ancestor of O'Brien, of Ballygarridan; 4. Turlogh; 5. Murtogh; 6. Dermod; 7. Donal
  27. Brian Catha-an-Aonaigh (or Brian of the Battle of Nenagh) who d. 1399: son of Maithan. Was twice m.: first to Slaine, dau. of Lochlan Laidir MacNamara. by whom he had three sons: 1. Teige na Glaoidh Mór (d. s. p.); 2. Mahon Dall, who had Turlogh, who had Brian, the progenitor of Siol Bhriain Debriortha (or the exiled); 3. Turlogh. Secondly, to Margaret, dau. of James Fitzgerald of Desmond, by whom he had Brian Udhar Catha, who was the ancestor of O'Brien, of Eachdroma

    FT120209     1400 AD

  28. Turlogh Bog: a younger son of Brian of the Battle of Nenagh; d. 1459. Was the hero of Glen Fogarty and Ballyanfoil; married Catherine, dau. of Ulick FitzWalter Burke, by whom he had issue: 1. Teige; 2. Donogh-Teige, bishop of Killaloe, who was called "Terence," by Ware; 3. Connor Mór na-Shrona, ancestor of O'Brien, of Sealhendhe, in Clare; 4. Turlogh Oge, who, from his dark complexion, was called "Gilla Dubh," and who was the progenitor of O'Brien, of Ballymacdoody; 5. Mahon, of Kilclaney; 6, Kennedy; 7. Brian Ganeagh; 8. Murtogh Beg
  29. Teige an-Chomhaid, or Teige of the Castle of Chomhad, in Burren, which he erected in 1459 in his father's lifetime: son of Turlogh Bog; d. 146S. He m. Annabella, dau. of Ulick Burke, son of "Ulick of the Wine," of Clanrickard, and had six sons: 1. Turlogh Donn; 2. Donal, whose sons Brian, Connor, and Murtogh possessed the estates known as Tir Briain Cacthnava, Dubh, and Dun-Hogan, all in the co. Clare; 3. Donogh, of Drom-fion-glas, who had four sons—Murtogh, Teige, Dermod, and Brian-na-Corcaidh (who divided his estates of Cahir-Corcrain, and Castletown, amongst his sons: I. Mahon, II. Murrogh, III. Connor, IV. Dermod, V. Murtogh, and VI. Teige-an-Comain); 4. Murtogh Garbh; 5. Murrogh; 6. Dermod Cleireach, of Cacthnava-na-Madara, who had six sons—I. Donall-na-Geall, II. Murrogh-an-Tarman, III. Brian-an Comhlack, IV. Mahon, V. Donogh, VI. Torlogh
  30. Turlogh Donn, who d. 1528: son of Teige-an-Chomhaid; married twice: first, to Joan, dau. of Thomas, eighth Lord Fitzmaurice (see No. 13 on the "Fitzmaurice" pedigree); and, secondly, to Raghnait, dau. of John MacNamara, of Clan Coilcain, and by her had:
    • I. Connor;
    • II. Donogh;
    • III. Murrough, first Earl of Thomond and Baron of Inchiquin;
    • IV. Teige, slain by Pierce, Earl of Ormond;
    • V. Dermod;
    • VI. Margaret, m. to Owen O'Rourke, of the county Leitrim;
    • VII. Slaine, m. to Henry Oge O'Neill, son of Henry, Prince of Ulster;
    • VIII. Fionala, who m. Manus O'Donnell, Chief of Tirconnell

Generation 121: O'Hart's 1892 Irish Pedigrees, "O'Brien (No. 2) Marquises of Thomond," page 163

  1. Murrough: son of Turlogh Donn; d. 1551; was the first "Earl of Thomond" and "Baron of Inchiquin; m. Eleanor, dau. of Thomas FitzGerald, Knight of the Valley, and had three sons and three daughters; the sons were:
    • I. Dermod of whom presently.
    • II. Teige, of Smithstown Castle, who m. Mór, dau. of Donal O'Brien, and had:
      • I. Turlogh, who d. s. p.
      • I. Honoria, who m. Richard Wingfield, an ancestor of the Viscounts Powerscourt.
      • II. Slaine, who m. Teige, son of Connor, the Third Earl of Thomond.
      • III. Hannah, who m. Donogh O'Brien.
    • III. Donogh, from whom descended O'Brien of Dromoland.
    The daughters were:
    • I. Margaret, b. 1535, who m. Richard, the second Earl of Clanricard.
    • II. Slaine, whose second husband was Sir Donal O'Brien, of Dough.
    • III. Honoria, who m. Sir Dermod O'Shaughnessy, of Gort, and had issue.

Generations 122 to 131: O'Hart's 1892 Irish Pedigrees, "O'Brien (No. 5) Barons and Earls of Inchiquin," pages 169-170

  1. Donogh; the third son of Murrough, the first Earl of Thomond; d. 1582. His father assigned to him the Castles and lands of Dromoland, Leamanagh, Ballyconnelly, Corcumroe, etc.; m. Slaine, dau. of John MacNamara Fionn, of Crathloe, and had one son and two daughters:
    • I. Connor, of whom presently.
    • I. Margaret.
    • II. Finola, who m. Uaithne O'Loughlin, of Moyrin, in Clare.
  2. Connor (who d. in 1603), of Leamanagh: son of Donogh; m. Slaine, dau. of Sir Turlogh O'Brien, of Dough Castle, and had a son:
  3. Donogh (2), who was knighted by King Charles I, and who d. in 1634. This Donogh m. Honoria, dau. of Richard Wingfield, an ancestor of the Viscounts Powerscourt, and had three sons and one daughter:
    • I. Connor, of whom presently.
    • II. Donogh, of Tobbermaile.
    • III. Murrough, who m. Hannah, dau. of his kinsman Turlogh O'Brien of Cluonan, and had a son named Teige.
    • I. Margaret, who m. Turlogh, son of Teige O'Brien of Dromore.
  4. Connor (2), of Leamanagh, who d. 1651: the eldest son of Donogh; m. Mary, dau. of Sir Turlogh MacMahon, and had two sons and two daughters:
    • I. Sir Donogh, of whom presently.
    • II. Teige, who m. the dau. of Captain Edward Fitzgerald, of Carrigowrane.
    • I. Honoria, who married Donogh O'Brien, of Dough. II. Mary, who m. Donogh MacNamara.
  5. Sir Donogh, of Leamanagh and Dromoland: son of Connor; d. 1717. Was created a Baronet on the 9th of Nov., 1686. He was twice married: first, to Lucia, dau. of Sir George Hamilton, by whom he had a son Lucius, of whom presently; and secondly, to Eliza, dau. of Major Deane, by whom he had:
    • II. Henry.
    • I. Honoria.
    • II. Elizabeth.
  6. Lucius: son of Sir Donogh by his first marriage; d. (before his father) in 1717; m. Catherine, dau. of Thomas Keightley, of Hertfordshire, and had two sons and two daughters:
    • I. Sir Edward, of whom presently.
    • II. Thomas.
    • I. Anne.
    • II. Lucia.
  7. Sir Edward, of Dromoland, M.P.: son of Lucius; was the second Baronet; d. 1765. Sir Edward m. Mary, dau. of Hugh Hickman, of Fenloe, and had:
    • I. Sir Lucius-Henry, of whom presently.
    • II. Donogh.
    • III. Edward.
    • I. Henrietta.
    • II. Anne.
    • III. Mary.
    • IV. Catherine, who m. Charles MacDonnell, of New Hall, near Ennis.
    • V. Lucia.
  8. Sir Lucius-Henry, of Dromoland, M.P., the third Baronet: son of Sir Edward; d. 1795; m., in 1768, Nichola, dau. of Robert French, of Monivea Castle, in the co. Galway, M.P., and had:
    • I. Sir Edward, of whom presently.
    • II. Lucius.
    • III. Robert.
    • IV. Donogh.
    • V. Henry.
    • I. Nichola.
    • II. Henrietta.
    • III. Catherine.
    • IV. Lucy.
    • V. Anna-Maria.
    • VI. Charlotte.
  9. Sir Edward, of Dromoland, the fourth Baronet, who d. in 1837; son of Sir Lucius-Henry; m. in 1799, Charlotte, dau. of William Smith, of Cahirmoyle, Newcastle West, in the county Limerick, and had:
    • I. Sir Lucius, of whom presently.
    • II. William Smith O'Brien, M.P. (b. 17th Oct., 1803; d. 18th June, 1864), heir to the estates of his maternal grandfather William Smith; the "Wallace" of his country, who, on the 19th Sept., 1832, m. Lucy-Caroline (d. 13th June, 1861), eldest dau. of Joseph Gabbett, Esq., of Limerick, and, besides a daughter Charlotte-Grace (living in 1887), the good and philanthropic Miss C. G. O'Brien, of Emigration fame in Ireland, had Edward-William, J.P., (b. 23rd Jan., 1837, and living in 1887), of Cahirmoyle, co. Limerick. William Smith O'Brien d. in Wales, but his remains were brought to Ireland and interred at Rathronan, co. Limerick.
    • III. Edward.
    • IV. Robert.
    • V. Henry.
    Sir Edward's daughters were:
    • I. Granna (or Grace).
    • II. Anne.
    • III. Harriet.
    • IV. Catherine.
    • V. Leney.

    FGC13418     1800 AD

  10. Sir Lucius, of Dromoland, the fifth Baronet, and thirteenth Baron of Inchiquin: son of Sir Edward; b. 1800, d. 1872; m. twice: first, Mary, dau. of William Fitzgerald, Esq., of Adelphi, co. Clare, by whom he had one son and three daughters:
    • I. Edward-Donogh, of whom presently.
    • I. Juliana-Cecilia, b. 1839.
    • II. Charlotte-Anne, b. 1840.
    • III. Mary-Grace, b. 1848.
    Sir Lucius was secondly m. (on 25th Oct., 1854) to Louisa, dau. of James Finucane, Esq.

Generations 132 to 135: Burke's Peerage

  1. Edward Donough O'Brien, 14th Baron of Inchiquin (M, #17941) was born on 14 May 1839. He was the son of Lucius O'Brien, 13th Baron of Inchiquin and Mary FitzGerald. He married, firstly, Hon. Emily Holmes à Court, daughter of William Henry Ashe Holmes à Court, 2nd Baron Heytesbury of Heytesbury and Elizabeth Worsley-Holmes, on 21 August 1862. He married, secondly, Hon. Ellen Harriet White, daughter of Luke White, 2nd Baron Annaly of Annaly and Rathcline and Emily Stuart, on 29 January 1874. He died on 9 April 1900 at age 60. He graduated from Cambridge University, Cambridge, Cambridgeshire, England, with a Master of Arts (M.A.). He held the office of High Sheriff of County Clare in 1862. He succeeded to the title of 14th Baron of Inchiquin [I., 1543] on 22 March 1872. He succeeded to the title of 6th Baronet O'Brien, of Lemeneagh and Dromoland, co. Clare [I., 1686] on 22 March 1872. He was invested as a Representative Peer [Ireland] between 1873 and 1900. He held the office of Lord-Lieutenant of County Clare between 1879 and 1900. He gained the rank of Honorary Colonel in the service of the 7th Brigade South Irish Division, Royal Artillery. He was invested as a Knight, Order of St. Patrick (K.P.) in 1892.
  2. Lucius William O'Brien, 15th Baron of Inchiquin (M, #28636) was born on 21 June 1864. He was the son of Edward Donough O'Brien, 14th Baron of Inchiquin and Hon. Emily Holmes à Court. He married Ethel Jane Foster, daughter of Johnston Jonas Foster, on 14 January 1896. He died on 9 December 1929 at age 65. He gained the rank of Lieutenant in the service of the Rifle Brigade. He held the office of Deputy Lieutenant (D.L.) of County Clare. He held the office of Justice of the Peace (J.P.) for Shropshire. He was invested as a Representative Peer [Ireland] between 1900 and 1929. He succeeded to the title of 7th Baronet O'Brien, of Lemeneagh and Dromoland, co. Clare [I., 1686] on 9 April 1900. He succeeded to the title of 15th Baron of Inchiquin [I., 1543] on 9 April 1900. He held the office of Senator [Irish Free State] in 1921.
  3. Hon. Fionn Myles Maryons O'Brien (M, #484007)was born on 28 October 1903. He was the son of Lucius William O'Brien, 15th Baron of Inchiquin and Ethel Jane Foster. He married Josephine Reine Bembaron, daughter of Joseph Eugene Bembaron, on 21 June 1939. He died on 2 August 1977 at age 73. He was educated at Radley College, Abingdon, Oxfordshire, England. He was educated at Loughborough College, Loughborough, Leicestershire, England. He fought in the Second World War. He gained the rank of Flight Lieutenant in 1941 in the service of the Royal Air Force Volunteer Reserve.
  4. Conor Myles John O'Brien, 18th Baron of Inchiquin (M, #484010) was born on 17 July 1943. He is the son of Hon. Fionn Myles Maryons O'Brien and Josephine Reine Bembaron. He married Helen O'Farrell, daughter of Gerald Fitzgerald O'Farrell, in 1988. He was educated at Eton College, Windsor, Berkshire, England. He was Aide-de-Camp to Commander British Forces Gulf. He gained the rank of Captain in the service of the 14th/20th King's Hussars. He gained the rank of GSO(3) in the service of the POLMIL Hong Kong. He was Corporate Officer for Inter Alpha Asia (Hong Kong) between 1979 and 1981. He succeeded to the title of 10th Baronet O'Brien, 17th Baron of Inchiquin [I., 1686] in 1982. He succeeded to the title of 18th Baron of Inchiquin [I, 1543] in 1982. He was managing director of Dromoland Devpt Company in 1983. He held the position of Chief of the Name and Arms of O'Brien of Thomond and Prince of Thomond. He lived in 2003 at Thomond House, Dromoland, Newmarket on Fergus, County Clare, Ireland.

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Brian Boru Timeline

Below is a timeline for L226 and Brian Boru DNA and ancient pedigrees.

347Cas born, sixth in descent from Cormac Cas, King of Munster
940Brian Boru born in Killaloe, County Clare
950Surnames adopted by Brian Boru and people generally in Ireland
1014Brian Boru dies at the Battle of Clontarf, north of Dublin
1632-1636Brian Boru described in Annals of the Four Masters
1634Brian Boru described in Keating's The History of Ireland
1652Cromwellian Settlement
1892Brian Boru described in O'Hart's Irish Pedigrees
2006Dalcassian DNA identified by Ken Nordtvedt and Irish Type III website started by Dennis Wright
2009L226 SNP identified and named by Thomas Krahn at FTDNA. L226 project started at FTDNA by Dennis Wright
2013Big Y test introduced by FTDNA. DC782 (900 AD) SNP named after Dál Cais, by Dennis Wright

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L226 and O'Brien Testing Projects

If you are a male with the name associated with Brian Boru, you may benefit from participating in the L226 DNA Project at Family Tree DNA. You should also participate in the surname project. There are two O'Brien projects: O'Brien DNA Project and Bryan DNA Project. But beware of the fact that practically all Irish surnames have multiple origins.

The L226 DNA Project was started by Dennis Wright in December 2009. The project is designed to encourage men with likely L226 DNA to test for the L226 SNP (single nucleotide polymorphism). It is limited to those who have tested positive for the L226 SNP or have ordered the test. You are likely to test positive for the L226 SNP if you are in the R1b1a2 haplogroup and have values of 8-9 for marker 459. These are the 14th and 15th markers. Having an historical surname does not guarantee that you will have L226 and Brian Boru DNA because most surnames have multiple origins.

You can participate in the L226 project as well as a project specifically set up for your surname. There is no additional cost for being part of two projects.

By testing the Y-chromosome DNA, males can determine the origin of their paternal line. Note that the Y-chromosome DNA strictly checks the paternal line, with no influence of any females along that line. Females do not receive the Y-chromosome, and therefore females cannot be tested for the paternal line. If you are a female and would like to know about your paternal line, you would have to find a brother or a male relative from that line willing to be tested.

The two swabs and scraper tubes in the FTDNA Kit. For more on how it's done, see "DNA Collection Method" by Dave Dorsey.
Y-chromosome DNA goes back male to male like traditional surnames.

You sign up online for FTDNA and they deduct the cost from your credit card. They send you in the mail a kit containing two scrapers that you use to swab the inside of your cheeks in four-hour intervals. You return the scrapers in receptacles and mailer provided in the kit. You get final results on line two months later.

If you decide to have your DNA tested, you should consider the ultimate test, which is Big Y-700. There are intermediate tests, but they will not tell you whether you have BriaBrian Boru DNA.

Most names have multiple origins. For this reason, your results may show that your DNA does not match the Brian Boru DNA, which will lead you in a different ancestry direction.

Table of Contents     

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