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Kings of Leinster


m. AIFE, d. of Gilla Patriac Mac Donnchada, King of Osraige


  • 2I. DERMOT- m. DEARBFORGAIL, d. 1072
  • Domnall-

    2I. DERMOT MacMAILNAMO ( DONNCHAD Mac DIARMATA 1)- King of Ireland

    d. 7 Feb. 1072

    "Diarmait mac Maíl na mBó was king of Leinster and a contender for the title of High King of Ireland. He was one of the most important and significant Kings in Ireland in the pre-Norman era. His influence extended beyond the island of Ireland into the Hebrides, the Isle of Man and even into England.

    Diarmait belonged to the Uí Cheinnselaig, a kin group of south-east Leinster centered around Ferns. His father, Donnchad mac Diarmata, more commonly known by the epithet Máel na mBó, whence Diarmait's patronym came. The last of Diarmait's ancestors to have been crowned as king of all Leinster was Crimthann mac Énnai, whose death is placed in the late 5th century, but his ancestors, most recently his great-grandfather Domnall mac Cellaig (died 974), had been counted among the kings of the Uí Cheinnselaig. Diarmait's mother was Aife, daughter of Gilla Pátraic mac Donnchada, king of Osraige. He had at least one sibling, a brother named Domnall whose son Donnchad mac Domnaill Remair was later king of Leinster.(1)

    The Uí Cheinnselaig had been prominent in earlier times, but their power had been broken at the battle of Áth Senaig in 738. The rival Uí Dúnlainge, based in northern Leinster around Naas and Kildare, who also enjoyed the support of the powerful Clann Cholmáin kings of Mide, dominated Leinster until the time of Brian Bóruma. The decline of Clann Cholmáin, and the defeat inflicted on the Uí Dúnlainge, led by Máel Mórda mac Murchada, at the battle of Clontarf in 1014, changed the political landscape to favour the Uí Cheinnselaig once more.(2)

    The return of the Vikings to Ireland in the early 10th century brought with it the creation of new towns on the coasts. The towns, centers of trade and manufacture, would give significant political power to those who could control their wealth. Kings of Leinster were in a particularly advantageous position to exploit this new wealth as three of the five principal towns lay in or near Leinster. In Leinster proper, in the south-eastern corner dominated by the Uí Cheinnselaig, lay Wexford. To the west of this, in the smaller kingdom of Osraige, which had been attached to Leinster since the late 10th century, was Waterford. Finally, the most important Viking town in Ireland was Dublin, which lay at the north-eastern edge of Leinster. Compared to this, kings in the north and west of Ireland had easy access to no towns, while those in the south, in Munster, had access to two, Cork on the south coast and Limerick on the west coast.(3)

    Dermot made an alliance with Niall mac Eochada, king of Ulaid, which helped to put pressure both from the north and south on the kingdoms of Mide, Brega and Dublin which were ruled by the High King.(4)

    This alliance paid off handsomly as the High King, who up till then had Dublin as a subject kingdom, was unable to prevent it slipping into the hands of Diarmait.

    In time he was able to claim the title "King of Leinster" and install his son, Murchad, as King of Dublin. Thus ruler of two of the most powerful and wealthy towns on the island, he was able to make a bid for the High-Kingship. It was during a battle against the king of Mide, Conchobar Ua Maelsechalinn, that he was killed, near to Navan, County Meath, on 7 February 1072.

    The surviving sons of King Harold Godwinson of England escaped to Leinster after the Battle of Hastings in 1066 where they were hosted by Diarmait. In 1068 and 1069 Diarmait lent them the fleet of Dublin for their attempted invasions of England.

    Diarmait's Death is mentioned in the Annals of the Four Masters:

    Diarmaid, son of Mael-na-mbo, King of Leinster, of the foreigners of Ath-cliath, and of Leath-Mogha-Nuadhat, was slain and beheaded in the battle of Odhbha, on Tuesday, the seventh of the Ides of February, the battle having been gained over him by Conchobhar O'Maeleachlainn, King of Meath. There were also slain many hundreds of the foreigners and Leinstermen, along with Diarmaid, in that battle. In it was killed Gillaphadraig O'Fearghaile, lord of the Fortuatha, &c. Of the death of Diarmaid was said:

    Two, seven times ten above one thousand,
    From the birth of Christ is reckoned,
    To this year, in which Diarmaid,
    First man in Leinster, fell.
    Diarmaid, of the ruddy-coloured aspect,
    A king who maintained the standard of war,
    Whose death brought scarcity of peace,
    The loss of the heroes of Ladhrann, with their ships.
    Comely youths were cut down there,
    Together with the head of Claire and Cualann.
    It caused in the breeze an unpleasant noise,
    The loss of the King of Riada of great valour.
    Until at Muillenn-Chul was slain
    A brave chieftain of a strong fortress,
    Until the furious fire-brand fell by treachery,
    They found no hero who dared with him contend.
    It is a red wound through my firm heart;
    For the host from Caindruim it was not just
    To destroy our noble chief they had no right,
    It has quenched their spirit greatly,
    Diarmaid of the laughing teeth under violent sorrow;
    There is not on account of his death banquet or feast;
    There will not be peace, there will not be armistice." (5)


  • 2I. MURCHAD- d. 1090


    (1) Hudson, "Diarmait"; Byrne, Irish Kings, pp. 271–272 & 290
    (2) Byrne, Irish Kings, pp. 271–272 & 290; Hudson, Viking Pirates, pp. 137–142; etc
    (3) DOC, EMI; Hudson, VP
    (4) N.B.: DOC, EMI, p. 54

    2I. MURCHAD (DERMOT 1)- King of Leinster

    d. 1090


    3I. DONCHAD- d. 1126

    3I. DONCHAD (DERMOT 1, MURCHAD 2)- King of Leinster

    d. 1126


  • 4I. ENNA- d. 1126

    4I. ENNA (DERMOT 1, MURCHAD 2, DONCHAD 3)- King of Leinster

    d. 1126

    Enna was killed in battle in 1126 by the Dublin Vikings that were ruled by his cousin Sigtrygg Silkbeard, and was buried in Dublin along with the body of a dog, considered to be a huge insult.


  • 5I. DERMOT MacMORROUGH- d. 1170

    5I. DERMOT MacMORROUGH (DERMOT 1, MUCHAD 2, DONCHAD 3, ENNA 4)- King of Leinster

    2. Sadhbh of Ui Fhaolain
    d. 1170

    "After the death of his older brother, Mac Murchadha (Dermot) unexpectedly became King of Leinster. This was opposed by the then High King of Ireland, Toirdelbach Ua Conchobair who feared (rightly so) that Mac Murchadha would become a rival. Toirdelbach sent one of his allied Kings, the belligerent Tigernán Ua Ruairc (Tiernan O'Rourke) to conquer Leinster and oust the young Mac Murchadha. Ua Ruairc went on a brutal campaign slaughtering the livestock of Leinster and thereby trying to starve the province's residents. Mac Murchadha was ousted from his throne, but was able to regain it with the help of the Leinster clans in 1132. Afterwards followed two decades of an uneasy peace between Ua Conchobhair and Diarmaid. In 1152 he even assisted the High King to raid the land of Ua Ruairc who had by then become a renegade.

    Mac Murchada also is said to have "abducted" Ua Ruairc's wife Dearbhforghaill (Dervorgilla) along with all her furniture and goods, with the aid of Dearbhforghaill's brother, a future pretender to the kingship of Meath. It was said that Dearbhforghaill was not exactly an unwilling prisoner and she remained in Ferns with MacMurrough, in comfort, for a number of years. Her advanced age indicates that she may have been a refugee or a hostage. Whatever the reality, the "abduction" was given as a further reason for enmity between the two kings.

    After the death of the famous High King Brian Boru in 1014, Ireland was at almost constant inter-dynastic civil war for two centuries. After the fall of the O'Brien family (Brian Boru's descendants) from the Irish throne, the various families which ruled Ireland's four provinces were constantly fighting with one another for control of all of Ireland. At that time Ireland was a confederal kingdom, and not a unitary state, with five autonomous provinces, Ulster, Leinster, Munster, Connaught and Meath, each ruled by kings who were all supposed to be loyal or at least respectful to the High King of Ireland.

    As king of Leinster, in 1140-70 Dermot commissioned Irish Romanesque churches and abbeys at Baltinglass - a Cistercian abbey (1148), Glendalough, Ferns (his capital - St Mary's Abbey Augustinian Order), Killeshin, and he sponsored convents (nunneries) at Dublin (St Mary's, 1146), and in c.1151 two more at Aghade, County Carlow and at Killculliheen in County Kilkenny. He also sponsored the successful career of churchman St Lawrence O'Toole (Lorcan Ua Tuathail). He married O'Toole's half-sister Mor in 1153 and presided at the synod of Clane in 1161 when O'Toole was installed as archbishop of Dublin.(2)

    In 1166, Ireland's new High King and Mac Murchadha's only ally Muircheartach Ua Lochlainn had fallen, and a large coalition led by Tighearnán Ua Ruairc (Mac Murchadha's arch enemy) marched on Leinster. Ua Ruairc and his allies took Leinster with ease, and Mac Murchadha and his wife barely escaped with their lives. Mac Murchadha fled to Wales and from there to England and France, in order to have King Henry II's consent to be allowed recruit soldiers to bring back to Ireland and reclaim his kingship. On returning to Wales, Robert Fitzstephen helped him organize a mercenary army of Norman and Welsh soldiers, including Richard de Clare, 2nd Earl of Pembroke, alias Strongbow.

    In his absence Ruaidhrí Ua Conchobhair (son of Mac Murchadha's former enemy, High King Toirdhealbhach) had become the new High King of Ireland. Mac Murchadha planned not only to retake Leinster, but to oust the Uí Conchobhair clan and become the High King of Ireland himself. In 1167 he quickly retook Dublin, Ossory and the former Viking settlement of Waterford, and within a short time had all of Leinster in his control again. He then marched on Tara (then Ireland's capital) to oust Ruaidhrí. Mac Murchadha gambled that Ruaidhrí would not hurt the Leinster hostages which he had (including Mac Murchadha's eldest son, Conchobhar Mac Murchadha). However Ua Ruairc forced his hand and they were all killed. Diarmaid's army then lost the battle. He sent word to Wales and pleaded with Strongbow to come to Ireland as soon as possible. Strongbow's small force landed in Wexford with Welsh and Norman cavalry and took over both Waterford and Wexford. They then took Dublin. MacMurrough was devastated after the death of his son, Domhnall, retreated to Ferns and died a few months later.

    Strongbow married Dermot's daughter Aoife of Leinster in 1170, as she was a great heiress, and as a result much of his (and his followers') land was granted to him under the Irish Brehon law, and later reconfirmed under Norman law.

    The scholar Áed Ua Crimthainn was probably Diarmait's court historian. In his Book of Leinster, Áed seems to be the first to set out the concept of the rí Érenn co fressabra, the "king of Ireland with opposition", later more widely adopted. This described Diarmait's ambitions and the achievements of his great-grandfather Diarmait mac Maíl na mBó.(3)

    In Irish history books written after 1800 in the age of nationalism, Diarmaid Mac Murchadha was often seen as a traitor, but his intention was not to aid an English invasion of Ireland, but rather to use Henry's assistance to become the High King of Ireland himself. He had no way of knowing Henry II's ambitions in Ireland. In his time, politics was based on dynasties and Ireland was not ruled as a unitary state. In turn, Henry II did not consider himself to be English or Norman, but a French Angevin, and was merely responding to the realities on the ground.

    Gerald of Wales, a Cambro-Norman historian who visited Ireland in 1185 and whose uncles and cousins were prominent soldiers in the army of Strongbow, repeated their opinions of Mac Murchadha:

    Now Dermot was a man tall of stature and stout of frame; a soldier whose heart was in the fray, and held valiant among his own nation. From often shouting his battle-cry his voice had become hoarse. A man who liked better to be feared by all than loved by any. One who would oppress his greater vassals, while he raised to high station men of lowly birth. A tyrant to his own subjects, he was hated by strangers; his hand was against every man, and every man's hand against him.

    After Strongbow's successful invasion, Henry II mounted a second and larger invasion in 1171 to ensure his control over his Norman subjects, which succeeded. He then accepted the submission of the Irish kings in Dublin in November 1171. He also ensured that his moral claim to Ireland, granted by the 1154 papal bull Laudabiliter, was reconfirmed in 1172 by Pope Alexander III, and also by a synod of all the Irish bishops at Cashel. He added "Lord of Ireland" to his many other titles. Before he could consolidate his new Lordship he had to go to France to deal with his sons' rebellion in 1173.

    Ua Conchobhair was soon ousted, first as High King and eventually as King of Connacht. Attempting to regain his provincial kingdom, he turned to the English as Mac Murchadha had before him. The Lordship directly controlled a small territory in Ireland surrounding the cities of Dublin and Waterford, while the rest of Ireland was divided between Norman and Welsh barons. The 1175 Treaty of Windsor, brokered by St Lawrence O'Toole with Henry II, formalized the submission of the Gaelic clans that remained in local control, like the Uí Conchobhair who retained Connacht and the Uí Néill who retained most of Ulster.

    Dermot's male-line descendants such as Art Mac Art continued to rule parts of Leinster until the Tudor re-conquest of Ireland in the 1500s. Today they live on with the surname "MacMurrough Kavanagh" at Borris in Co. Carlow and at Maresfield, East Sussex, being one of the few surviving "Chiefs of the name".(4) The currently recognized chief of the name is William Butler Kavanagh, The MacMorrough Kavanagh, Prince of Leinster (b. 1944) (1).

    Through his daughter Aoife, Dermot is also an ancestor of a great number of historically-famous people, including George Washington, Marie-Antoinette, Lord Edward Fitzgerald, Robert Emmet, Charles Darwin and Winston Churchill."(5)


  • I. Urlachan- m. Donnell More, King of Thomond
  • 6II. AOIFE- m. RICHARD de CLARE, d. after 1189
  • III. Donell- Donald 'the Handsome' was King of Leinster and was killed in 1175


    (1) Irish Pedigrees- John O'Hart, Dublin, 1892- Vol. I, pp. 157, 555
    (2) Tahdg O'Keefe essay in JRSAI- vol.127 pp.52-79 (1997)
    (3) Byrne, Francis John (2005), Ireland and her neighbours, c.1014–c.1072- Francis John Byrne- in Dáibhí Ó Cróinín's, Prehistoric and Early Ireland, A New History of Ireland- Oxford University Press, 2005- Vol. I, pp. 862–898
    (4) Notes on the armless and legless Arthur (1831-89)

    Burke's Irish Family Records- Hugh Montgomery Massingberd, ed.- Burkes Peerage Ltd., London 1976- pp.651

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