The Dál gCais

     For centuries it was taught that the O’Brien Clan, senior house of the Dál gCais, were cousins to the Eóghanacht of Munster. That the two Irish families shared a common ancestor in Oilill Ólum, King of Munster about 150 A.D. The traditional story states that the Eóghanachtas and the Dalcassians were to switch the kingship of Munster every other generation. But this never happened until the rise of Mathgamain and his taking of the kingship of Munster in 970 A.D. However, this tradition  is propaganda!
     The traditional tale was put under the microscope by Rev. John Ryan in 1943, and again by John V. Kelleher in 1967. The traditional story is nice, but it appears not to be on firm facts. Ryan outlines and explains the correct descent of the Dál gCais. Kelleher gives several theories of why and how the Dál gCais rose to power. Theories is all that can be offered, for facts in Irish history for this time is fragmentary.
     Ryan writes that long before the establishment of Christianity in Ireland in the early 400s A.D., the Old Gaelic words of dál and corcu were used to designate specific groups of people. Dál means “part of,” an example would be the Dál Rete (Dál Riada), who established a small kingdom in northeast Ireland, and later into Scotland about 500 A.D. Another word that became interchangable with dál, is corcu. An example would be the Corcu Loegde. Another form of dál and corcu, is the termination  word ríge, as found in the tribal names of Osraige and Muscraige. So Dál gCais means “part of Cais,” i.e., “descendant of Cas.” After the coming of Christianity one will find the use of the sept-names beginning with Uí, as in Uí Briain.
     It was during the 5th century that the various annals of Ireland were recording the affairs of the prominent people of Ireland. But the Dál gCais name isn’t recorded until 934 A.D., in a Munster record called the Annals of Inisfallen, with the death of, “Rebachan son of Mothlae, abbot of Tomgraney, and king of Dál Chais.”  The next mention of the Dál gCais is in a monastery compilation titled Chronicon Scotorum. In the year 951 it records the death of Cennédie, son of Lorcán, as king of Dál gCais (rí Dáil cCais). 963 mentions the plundering of Dál gCais by Fergal O Ruairc. And in the Book of Rights, recorded about 1000 A.D., the Dál gCais are mentioned prominently. And lastly, the Annals of Ulster don’t mention the Dál gCais until 1053 A.D. when, “MacLochlainn and the men of Mag Itah slew Cumacha, son of Clairchen, moer Dáil Chais, apparently in Cenél mBinnig, Derry.” This is the time of Brian Boru and his kindred. The general term for the O’ Briens and their kindred from this time on is Dál gCais. As a known people though, the name of Dál gCais didn’t exist before 900 A.D.
     So what are the true origins of the people known today as the Dál gCais?
     Eóin MacNeill was the first to show that the Dál gCais were of Dési (Day-shee) origin. The Dési lived in the lands of Waterford and southern Tipperary, an area covered today by the Diocese of Waterford. The ancient meaning of the Gaelic word dési, meant a people who were vassals. A term that could be applied to a number of communities. It would appear though that the Dési of Waterford were a very cohesive entity which alludes to the possibility of them having common descent.
     Tradition tells us, says Ryan,  that the Dési were “nobody’s darlings,” for a couple of centuries. Driven around Ireland trying to exist. Then came a series of wars between Munster and Leinster for the control of “clar machaire na Muman,” a plain in Munster. The Dési sided with the Eóghanachtas, and helped in driving the Leinstermen back to the present Tipperary-Kilkenny border. The Eóghanachtas offered to the Dési as a reward large grants in Waterford and south Tipperary, which were extended in time to what would become east Limerick, and into north Tipperary. This northern stretch was very narrow. What the Dési were, was a buffer between the Eóghanachtas and Leinster.
     This northern settlement in Limerick became known as In Déis Becc. This area is believed to have been two sections; In Déis Tuaiscirt (the eastern Clare and northern Limerick area), and In Déis Descirt (southern Limerick and Tipperary area.) Tradition states that the kingship of Cashel was to pass every other generation between the two In Déis Becc tribes. But it appears that kingship didn’t enter the In Déis Tuaiscirt camp until 964 A.D. Ryan here suggests that it is highly plausible that the Dál gCais then invented the tale of alternating kingships, but added that it also included the Eóghanachtas, and here invented the genealogy to Eóghan Taldlech, founder of the Eóghanachta Dynasty, making their claim more believable.
     Lugaid Mend, a contemporary with Niall of the Nine Hostages,  is the common ancestor of all the clans of In Déis Tuaiscirt. Lugaid Mend was the son of Oengus Tirech, son of Fircorb, son of Mogcorb, son of Cormac Cas. It was Lugaid Mend who carried on the invasion of the southern end of Connacht started by King Crimthand Mór Mac Fidaig, an Eóghanachta Munster king who had just died. The final line the war defined is the present day boundary between Clare and Galway. Lugaid had taken away the lands of Clare from Connacht. And the bloodshed spilled was mostly done by the In Déis Tuaiscirt, who would settled the newly acquired lands. This was about 350 - 375 A.D. Lugaid Mend’s great-grandsons, Blod (Uí Bloid), Caisin (Uí Caisin), Aengus Cendnatrach (Cenél Fermaic), and Aengus Cendaitin (Cland Ifernain), all became founders of leading clans.
     A generation later was born  Carrthend, grandson of Lugid Mend, and King of Tuadmuma (Thomond), in the time of St. Patrick. Carrthend is said to have had a brother named Cairthend Find. Carrthend ruled the lands on the Limerick side of the Shannon River. He is the common ancestor of all succeeding kings. Three of his sons were kings of Thomond (In Déis Tuaiscirt.) Two of these sons were Oengus and Eochaid Ballderg (Redspot.) Eochaid is the proginitor of the O’ Briens and it’s kindred. Oengus’s lineage held the kingship of In Déis Tuaiscirt for generations.
     Oengus lineage split into three clans in later generations, the Uí Cernaig, Uí Rongaile, and Uí Eichtigern (Aherne), the latter were kings of In Déis Tuaiscirt. The Aherne Clan held onto a noble reputation far greater than the O’Briens and their kindred, until 900 A.D., but they retained a noble status as chiefs in the lands around Kilkishen well into the Middle Ages. 
     A grandson of Eochaid’s, Aed Caem, was the first to settle at Craig Liath, near Killaloe. A descendant of his was Toirdelbaig, King of Thomond, and progenitor of  Uí Toirdelbaig, from whom the O’Briens descend. His sons were Mathgamain (Cland Mathgamna), and St. Flannan, who died in 778 A.D. What helped the Uí Toirdelbaig rise to power was the coming of the Norse. Killaloe offered great defense as compaired to the Uí Cernaig, who were exposed to attack. Lorcán, assumed to be fifth in descent from Toirdelbaig, would be able to obtain the kingship of In Déis Tuaiscirt, the first of the clan to do so since the days of Eochaid Ballderg.
     From the 5th to the 9th centuries the history of Ireland makes little reference to the In Déis Tuaiscirt. In 712 King Dubduin or his nephew, Cernach (ancestor of Uí Cernaig), fought a victorious battle at Cahernarry against Cormac mac Maenach, King of Cashel, who was killed. The northern Déis were victorious against the Corcumruad in 743 A.D. Then came the Northmen in 922 A.D. up the Shannon River in their long-ships to the lands that would be called Luimnech, occupied by the In Déis Tuaiscirt. These lands were controlled by the Uí Eichtigern, who were later part of the Dál gCais. So it is not surprising that the Dál gCais considered themselves as over-lords of Limerick for hundreds of years.
     The northern Déis were terribly defeated by the Limerick Norse in 935 A.D.
     Early in the 10th century there appears to have been a struggle in the kingship for the northern Déis. What was common in dynastic disputes of succession, Ryan notes, was the appointing of an ecclesiastic. Appointed to the throne was Rebechán, son of Mothla, abbot of Tomgraney, who died in 934 A.D.
     After Lorcán’s reign as King of Thomond, his son Cennédie took over the throne. His lands were the four parishs of Killaloe, Bridgtown, Kilokennedy and Clonlara. As king it was up to him to prevent any expansiion of the Danes of Limerick power. Life was constant warfare. In 950 A.D., Congalach mac Maelmithid, King of Ireland, made a raid into Munster and two of Cennédie’s sons were killed, Donncuan and Eichtigern. The following year King Cennédie fell in battle. His son Lachtna replaced him on the throne. Lachtna built the Grianán Lachtna on Craig Liath. In three years Lachtna died and was succeeded by a younger brother, Mathgamain, who would overpower the Danes and Eóghanachta (who were fighting amongst themselves for many years over the kingship of Munster), becoming the King of Munster from 954 to 964 A.D. He was inaugurated at the Rock of Cashel.
     In Mathgamain’s tenth year as King of Munster, the Eóghanachtas assisted by the Danes of Limerick, created a trap and assassinated the king. An outraged younger brother sought revenge, and in a couple of years, Brian took the banner of the In Déis Tuaiscirt, now called Dál gCais, not only to Cashel but to Tara as well. 
     With the rise of fortunes for Brian Boru, the rest of his kindred had increased advantages also. As members of the  O’Brien’s (in the next few generations) moved from their lands in County Clare to sections of Limerick, Tipperary, and beyond; so went other Dál gCais families such as the O’ Hickeys (physicians), O’ Clancys, MacFlannchads (brehons), and the Mulqueens (Ó Maolcaoine, ollams). Also came are the Aherns, O’Deegans, O’Shanahans, O’Malleys, O’Neills, O’Liddys, MacMahons, MacNamaras, O’Gradys, O’Lonergains, O’Lynchs, O’Reidys, MacInerneys, O’Doyles, O’Griffins, Galvins, O’Hallorans, O’Hartigans, O’Sheedys, O’Slatterys, O’Hurleys, O’Scanlans, O’Tubidys, O’Sheehans, Arthurs, O’Spillanes, O’Moloneys, O’Kearneys, O'Maras, O’Toomeys, O’Hennesseys, O’Duffys, and the Hayes family of Clare. All this expansion was prepared for by the Uí Conaing. All these families were doing was returning to their ancestral lands in the County of Limerick. The city of Limerick became a second seat of the O’Briens once the Danes were controlled. It became their ruling seat, other than Killaloe, and before the 11th century, Muirchertach Ó Briain moved his capitol to Limerick. Here the Ó Briains would have stayed had not the Normans brought a deviation in that policy. 
Dál gCais banner

     The Dál gCais were now one of the most powerful families on the Emerald Isle. However their lineage was not impressive, but rather of  common stock. They were vassals.
     Kelleher’s theory is that the Dál gCais got their start with the help of the Midhe Uí Néill kings of Tara in the early years of the 10th century. The reason for this support was the Uí Néill hoped that the Dál gCais would be a wedge in keeping Munster divided. But Uí Néill power suddenly declined in the mid 900s, and the Dál gCais were able to continue the struggle in their ascent by themselves.
     One question to ask in all this is why did the Uí Néill choose the Dál gCais and not some other tribe or clan of Munster? Location. The Dál gCais territory lay on both sides of the Shannon River, from just north of Limerick to Lough Derg. The Dál gCais controlled the river entrance into the heartland of Ireland. They also controlled the portages, fords, and rapids of the river. Making it difficult for the Norse and their long-ships to carry on their military exploits into Ireland.
     To help in this ascent the Eóghanachta Dynasty, beginning with the death of King Fedelmid mac Crimthainn in 847 A.D. Fedelmid had been a most powerful rival to the Uí Néill of Tara. On his death Munster became very weak until Brian Boru gained control of the throne in 980 A.D. The Eóghanachta king at Cashel had to be strong in power to command all the loyalties of the 15 Eóghanachta clans and some 20 other tribes of the province. The Eóghanachta couldn’t produce such a man.
     The Eóghanachta genealogies which begin detailed, become very poor in by 800 A.D. Showing, writes Kelleher, that the dynasty was in deep decline, and that there was no effort to repair the genealogies. For the pedigrees were usually updated about every three or four generations. However, the genealogies of the Dál gCais are excellent till the emergence of the great families during the 11th century, who began keeping their own genealogies. It is at this time that there appears a new or revised pedigree showing the Dál gCais descended from Cormac Cas, son of Oilill Ólum, King of Munster about 150 A.D. This brought them into a cousin relationship with the Eóghanachta, who descended from Eóghan Mór, also a son of Oilill.
     Kelleher writes that this obviously wasn’t an invention of the Eóghanachta, nor was it an invention of the Dál gCais, for they weren’t strong enough in the 900s to make this grafting into the Eóghanachta pedigree stick. The only power resided with the Uí Néill of Tara.
     As early as 846 A.D., the Uí Néill had used the altering of prehistoric pedigrees as a political weapon. They altered many genealogies of families in north and east Munster to bring them away from dependence on Cashel, to a more semi-independence under the Uí Néill. This changed the Osraige tribe to join the Laigin, and the Dési (without In Déis Tuaiscirt) where made to descend from a brother of Conn Cetchathach. The Éle Deiscirt were made to descend from another brother. This continued with other tribes.
     In the annals the name of Dál gCais appears in 941 A.D., when Orlaith, the daughter of Cennédie mac Lorcáin, was put to death by Donnchad, king of Ireland, for sleeping with his son Oengus. Orlaith was one of four wives to the king, a second wife or royal concubine. Kelleher points out that this is important for it shows this was a political marriage involving the king of Tara and a petty kingship of the Dál gCais. Obviously he had no concern about a Dál gCais reprisal for Orlaith’s death, it was a warning to them to keep in their place.
     From 943 - 951 A.D., the Uí Néill were in dynastic struggles for the kingship of Tara. This left Munster free to itself. The Annals of Ulster record that in 944 A.D. there took place “the battle of Gort Rottacháin by Cellachan over Thomond, where many fell;” and in CS and FM “a victory by Cellachan Caisil over Cennétig mac Lorccáin in Mag Duine, where many fell.” It is clear that at this time Cennédie was regarded as king of Thomond.
     This is the first mention in all of the annals of Ireland that mentions Thomond. Again lending credibility to the theory that the creation of Thomond and the Dál gCais was of a recent creation. Before this time there are just a few mentions of the In Déis Tuaiscirt with no hint of eminence.
     A year before the death of King Cennédig, the Uí Néill struggles came to an end with the death of Ruaidrí úa Canannáin’s death in battle. Immediately Congalach’s attention turned south, and he raided west Munster and killed two of Cennédig’s sons, Echtigern and Donncuan.
     Cennédie was killed in 951 A.D. according to the Annals of Ulster who refer to him as “rí Tuath-muman” (rí is Gaelic for king). And the annal of CS styles him as “rí Dáil Cais,” and the Annals of Innisfallen call him “rígdoamna Cassil.” All very high notice for a man who has nothing victorious recorded for him.
     Lachtna mac Cennédie took over his father’s kingship, but he was killed a couple of years later by the Uí Floinn and Uí Cernaig, rival families to the Uí Toirdelbeg. Uí Cernaig were a branch of Clann Oengusa who had total domination of the kingship of the In Deis Tuasicirt since the end of the 7th century. And they wanted the kingship back. It is believed that Cormac mac Domnaill of Clann Oengusa, censored a great deal of the Dál gCais history, for there is no record of their kings from about 834A.D. until Abbot Rebechán mac Mothlai’s death in 934 A.D.
     During the time of 954 - 963 A.D., the Eóghanachta fought and killed each other’s branch kings. The following year the King of Thomond, Mathgamain, decided to sustain an all out war upon the Norsemen in Munster, and he marched an army to the Rock of Cashel, where the Muscaighe and the Eóghanachta Caisil gathered to his banner. Kelleher theorizes that at this time an agreement was entered into for an alternate kingship of Cashel between the Dál gCais and the Eóghanachta Caisil. They had modeled their arrangement after the Uí Néill and the same deal between the northern and southern branches in the rule of Tara. Mathgamain was recognized as the king of northern Munster, but that is all. From Cashel the Dál gCais struck out against the Limerick and Waterford Norsemen. The records of Cogadh Gaedhel re Gallaibh states that at this time the throne of Cashel was vacant. From 964 to 970/971 A.D., Mathgamain struggled for control of all of Munster finally obtaining it, only to reign for six years before being assassinated by the Eóghanachtas of Desmond, in 977 A.D., by King Máel-mud mac Brian. Máel-mud ruled for two years, being killed by an avenging brother named Brian mac Cennédie. The new Desmond king was his son, Cian, who would marry one of Brian’s daughters. Cian was killed in 1015 by an Eóghanachta rival. Who in turn was killed trying to overthrow the Dál gCais. The remaining sons of Brian, Tadg and Donnchad, proved to be to powerful, and they and their descendants ruled Munster for the next hundred years.
     Kelleher explains, “The firm insistence upon the right to alternate with the Eóganachta can only date from this period, for once Dál  Cais had control of the province, as they had from Brian’s time on, the effect of the claim would rather be the right of the Eóganachta to alternate with them.”
     Now is introduced the new genealogy for the Dál gCais. Kelleher states that the Eóghanachta Caisil saw their most valued possession disintegrating before them. If they could save it, even by sharing it with a new and powerful “kinsmen,” then the claims in the revised Dál gCais genealogy could be accepted as fact.

  1. Francis John Byrne, Irish Kings and High-Kings. (New York: St. Martin’s Press. Pp. 36-37.)
  2.  John V. Kelleher, “The Rise of the Dál Cais,” North Munster Studies. (Limerick: The Thomond Archaeoloical Society, 1967. Pp. 230-241.)
  3. Roger C. Newman, “The Dalcassians and Munster,” Brian Boru: King of Ireland. (Dublin: Anvil, 1983. Pp. 48-64.)
  4. Rev. John Ryan, S.J., D.Litt., “The Dalcassians,” North Munster Antiquarian Journal. Vol. 3, #4; Autumn, 1943.
  5. The Royal O’Briens; A Tribute. 1992.