The Normans came to Ireland at the invitation of Dermot McMurrough, King of Leinster, in 1169 and within a few years had conquered much of the east and south-east of the country. The Norman advance into Thomond was delayed for a long time, however, by a strong O'Brien opposition and they did not begin to have a major impact upon Clare until the middle of the thirteenth century. The intrusion of the Normans into Thomond was partly due to some of the O'Brien princes, who invited them into the territory to assist them in their own dynastic struggles. Naturally the Norman barons took advantage of the feuding clans to gain a foothold in the region. Thus the Norman adventure in Thomond was inextricably linked with the fortunes and factions of the ruling O'Brien family.

Dónal Mór O'Briain (1168 - 1194)
Dónal Mór was absolute king of Thomond when the Normans came and he was able to keep them at bay from his kingdom, which included Clare, Limerick, North Tipperary and part of Offaly, up to the time of his death in 1194. Dónal Mór had strong ties with some of the leading Norman families and he was not opposed to the English except where they threatened his kingdom. Both he and Strongbow married a daughter of Dermot McMurrough, King of Leinster; while Dónal Mór's daughter married Richard de Burgh a powerful Norman baron in Limerick and Galway. Dónal Mór even assisted Strongbow and the Normans in some of the campaigns against the Kings of Ossory, Desmond and Connaught (traditional enemies of the Uí Briain). When Henry II visited Ireland in 1171 Dónal Mór submitted to him at Cashel and paid homage, thus acknowledging Henry's lordship of Ireland. In agreeing to pay tribute to Henry II, Dónal Mór became in effect, a tenant-in-chief of the English king. Shortly after this submission Henry attempted to deprive Dónal Mór of his kingdom by granting all of Thomond to one of his knights, Philip de Braose, in 1173. When Philip and other Normans, including Strongbow, tried to enforce this claim by invading Thomond, they were repulsed by Dónal Mór's army at the battle of Thurles in 1174, in which over 700 were slain. In 1175 Raymond le Gros, another leading Norman adventurer, captured Dónal Mór's capital of Limerick by bringing a fleet up the Shannon. A year later, however, Dónal Mór re-gained the city and burnt it, rather than suffer it to be held by foreigners. From 1176 up to his death in 1194 the Normans made no further inroads into Thomond.

Donagh Cairbreach O'Briain (1198 - 1242)
When Dónal Mór died in 1194 his kingdom was weakened by rivalry between his three sons, and the Normans exploited this weakness to their own advantage. Murtagh Dall, the eldest son, was blinded by the Normans, then Conor Roe, the second son, was dethroned and murdered in 1198 by his nephew. Donagh Cairbreach, the third son, invited his brother-in-law de Burgh and other Normans to help him suppress the McNamara and O'Quin clans who were in revolt against his kingship. In return for this support, Limerick city was handed over to the Normans and grants of land were given in Limerick and Tipperary. During this time the Butlers and other Normans were pushing in to eastern Thomond (north Tipperary, east Limerick and south Offaly) so that by the year 1200 the kingdom of Thomond was greatly reduced and was almost co-terminus with the modern county Clare. Fortunately, the river Shannon was a natural barrier protecting the remaining O'Brien territory from further Norman expansion, but only for a while. Reflecting the changed political situation, Donough Cairbreach moved his capital to Clonroad (Ennis) around this time.

In the meantime, Prince John, Lord of Ireland, had visited Ireland in 1185 and he granted 5½ cantreds (baronies) of Thomond to Theobold Walter (Butler). This land was in east Clare, but the Butlers were not able to enforce this claim. By 1199 further grants had been made by King John. Arnold Keating received Tradaree (Bunratty lower), while the King retained for his own use the three cantreds of Corcobaskin (i.e. Moyarta, Clonderlaw and Ibrickan). Keating later exchanged his claim of Tradaree for Clonderlaw. Another Norman baron Thomas Fitzmaurice was rewarded with a grant of territory, worth 5 knights' fees, on the northern bank of the Shannon, near Limerick. However, these claims were not recognised by King Donogh Cairbreach until the year 1210 when King John visited Ireland and Donough submitted to him at Waterford. Donough acknowledged his status as tenant-in-chief, but Tradaree, Moyarta, Clonderlaw and Ibrickan were placed at the disposal of the Norman justiciar (chief governor) of Ireland, John de Gray, Bishop of Norwich. Although de Gray tried to colonise these areas he failed, due no doubt to O'Brien opposition, and Donough rented these lands from de Gray at a nominal sum, allowing some Norman settlers into the county.

A Norman Bishop of Killaloe
An Episcopal vacancy occurred in 1215 with the death of the bishop of Killaloe Conor Obrein. The chief justiciar of Ireland, Geoffrey de Marisco, who had lands in north Tipperary promoted his nephew Robert Travers and had him nominated for the diocese. Though he was recognised by the King of England and consecrated by the bishops of Limerick, Emly and Waterford (all of them Normans), the Irish disputed his election and appealed to the pope, Honorius III. The pope supported the arch-deacon and chapter of Killaloe and Bishop Travers was eventually deposed in 1221, while the archdeacon, Dónal O'Heini, was consecrated instead. But Travers refused to resign. With the support of his uncle the justiciar, who had built a castle at Killaloe in 1207, he held on as bishop with opposition until the year 1226 when the pope denounced, defrocked and excommunicated him. Thus the Norman attempt to control the church in the diocese of Killaloe was frustrated and was not repeated. Donogh Cairbreach ruled as King of Thomond until his death in 1242. He got a re-grant of the crown lands of Tradaree and Corcabaskin in 1222 for an annual rent of £100. This lease was renewed in 1228 and, even though his brother Murtagh bid against him, Donogh retained possession of these lands at a higher rent. In general, Donogh Cairbreach was loyal to the English interest and he assisted his Norman brother-in-law Richard de Burgh in his campaign against the O'Connor's, King of Connaught, in the 1230's.

Conor O'Briain (1242 - 1268)
Donogh Cairbreach was succeeded by his son Conor, and in 1250 he got a renewal of the lease of the lands rented by his father for a fine of 2,200 marks and an annual rent of £200. However by this time, the O'Brien tenure of Thomond had become very insecure, as in 1248 King Henry III granted the cantred of Tradaree to Robert de Muscregos, while in 1252 the cantred of the Isles (including Clonroad) was granted to John Fitzgeoffrey, the justiciar. Robert de Muscregos pursued his claim vigorously and immediately set about colonising Tradaree, building castles at Bunratty and Clare Castle. He also got the right in 1252 to establish fairs and weekly markets at these centres.

The fortresses at Clare Castle and Bunratty posed a strong threat to O'Brien power in Clare, being so close to Clonroad. So King Conor, urged on by his fiery son Teig, turned against the Anglo-Normans in 1257 and slaughtered many of the settlers, however the fortresses remained. De Muscregos had died in 1254 but his son John continued the settlement despite O'Brien opposition. King Conor O'Brien opposed the Norman settlers up to the time of his death in 1268, when he was succeeded by his younger brother Brian Rua.

Brian Rua (1268 - 1277)
Brian Rua continued his attacks upon the settlements and in 1270 he captured and burnt Clare Castle, which was never rebuilt by the Normans. John de Muscregos died in 1275 and his son Robert, perhaps finding the settlement too troublesome and unprofitable, returned the Manor of Bunratty to the King in exchange for some property in Wales. When King Conor O'Brien died in 1268 his tanaiste and eldest son Teig had pre-deceased him in 1259. Toirdealbach, one of Teig's sons, revolted against Brian Rua and with the support of the O'Dea and McNamara clans, captured Clonroad and expelled Brian Rua from Thomond in 1276. Also in 1276 King Edward II, taking advantage of the O'Brien feuding, granted all of Thomond to Thomas de Clare, a younger son of the Earl of Gloucester and a grandson of King Edward I.

Toirdealbach O'Briain (1276 - 1306)
Brian Rua the deposed King of Thomond, appealed to de Clare to help him regain his throne. In return for his support Brian Rua promised that he would allow de Clare to colonise all the land between Athsollus (in Quin) and Limerick. Brian Rua and his Norman ally Thomas de Clare, with a strong force, expelled Toirdealbach O'Briain and recaptured Clonroad. Toirdealbach fled to Galway and elicited support from his Norman cousin William de Burgh; together with assistance from the McNamara and O'Dea clans they defeated the combined forces of Brian Rua and Thomas de Clare 1277. King Brian Rua fled to Bunratty castle and there Thomas de Clare had him treacherously hanged and drawn.

The civil war between the O'Briens continued for some more years with de Burgh supporting Toirdealbach, while de Clare had become reconciled to Donogh, son of King Brian Rua, and assisted him. The bitter family feud ended temporarily in 1280 when de Clare attempted to impose a settlement by partitioning Thomond. Toirdealbach was to rule in East Thomond while Donogh was to reign in West Thomond. Toirdealbach, however, did not welcome the idea of ruling half a kingdom and hostilities resumed until Donogh was drowned during a party at Island Magrath on the Fergus near Clare Castle in 1284. From that date until his death in 1306 Toirdealbach ruled as undisputed King of Thomond. De Clare had no choice but to reach an accommodation with him and Toirdealbach rented part of the Bunratty manor at a rent of £121 p.a.

Meanwhile, in 1280, Thomas de Clare embarked upon a major castle-building project at Quin but this was destroyed by the McNamaras in 1285. Thomas de Clare died in 1287 leaving behind him a thriving Norman manor and stronghold at Bunratty castle. At the time of his death his sons Gilbert and Richard were minors. The minority of the de Clare's was a factor which aided Toirdealbach to rule without strong Norman opposition.

Donogh O'Briain (1306 - 1311)
Donogh, son of Toirdealbach became King in 1306; however, the clan rivalry over the succession again erupted into warfare, with Richard de Clare supporting the claims of his protégé Dermot O'Briain, (son of Donogh, son of Brian Rua) of clan Brian; while William de Burgh supported the claims of Donogh O'Briain (son of Toirdealbach, son of Teig) of clan Toirdealbach. After a battle at Bunratty, Donogh fled and was killed by his cousins at Corcomroe in 1311.

Dermot O'Briain (1311 - 1313)
After the death of Donagh, de Clare had Dermot, his ally, crowned at Magh Adhair but de Burgh objected to him and put Muirceartach (a brother of the late King Donogh) in control. However, de Clare and his allies expelled Muirceartach. De Clare suggested a partition of Thomond but this was rejected.

Donogh O'Briain (1313 - 1317)
King Dermot died suddenly in 1317 and his cousin Donogh of the clan Brian succeeded. However, Muirceartagh and his ally de Burgh continued to oppose the clan Brian Kings, but King Donogh expelled Muirceartagh in 1314.

The Bruce invasion (1315-1317)
The political scenario was radically transformed and complicated in 1315 by the invasion of Robert de Bruce, King of Scotland, and his brother Edward. King Donogh and clan Brian elected to support Edward Bruce and to oppose the English settlement in Ireland. Richard de Clare was now an enemy of Donogh and clan Brian, while he had always opposed clan Turlough. Without the support of Richard de Clare King Donogh fled to Connaught and he later joined the Bruce camp. His rival Muirceartach was now supreme in Clare.

Muirceartach O'Briain (1317 - 1343)
In 1317 the exiled King Donogh persuaded the Bruce brothers to invade Munster to drive the English from Thomond as well as his usurping cousin Muirceartach. Muirceartach joined de Clare, de Burgh and other Norman barons at Cashel to oppose their common enemy, but after reaching Castleconnell the Bruce army retreated towards Dublin, leaving King Donogh and his army behind. Muirceartach attended a parliament in Dublin and while he was there his brother Dermot determined to destroy clan Brian. At the battle of Corcomroe in 1317, Donogh and most of the clan Brian army were killed, his son Brian Bane escaped with a few followers and went to Tipperary. When Muirceartach returned from Dublin in 1317 almost all of Clare rallied to him, with the exception of Richard de Clare and his protégé Mahon O'Brian who acted as de Clare's agent in west Clare. De Clare again tried to divide the county between the feuding O'Brian's but Muirceartach refused to accept an imposed settlement from de Clare (who had always opposed clan Turlough). Muirceartach banished Mahon O'Briain and refused to accept any authority from de Clare. War was the only solution to this struggle between Muirceartach O'Briain and Richard de Clare for control of Thomond.

The Battle of Dysart O'Dea 1318
Richard de Clare led an expedition against Conor O'Dea and his clan of Dysart O'Dea, who were faithful supporters of Muirceartach and the clan Turlough. Conor O'Dea called upon his neighbouring clans under Felim O'Connor and Loughlin O'Hehir to assist him (Muirceartach was in East Clare at the time). On the tenth of May 1318, Richard de Clare and a strong force of Normans, with the support of the sons of Mahon O'Briain and Brian O'Brian a brother of the late King Donogh, approached O'Dea's territory. Confidently, de Clare divided his force into three sections. With an inferior force in men and arms O'Dea's strategy was to set up a trap for de Clare at the ford of Ballycullen near Dysart O'Dea. Richard de Clare at the head of his section raced across the ford after some of O'Dea's men acting as decoys. Then Conor O'Dea and his army came out of hiding and cut off de Clare's retreat. Richard de Clare was killed along with most of his section. The remainder of de Clare's army forced a crossing of the ford and surrounded O'Dea's army, which retreated towards a wood. Then Felim O'Connor's and Loughlen O'Hehir's men joined the battle giving some relief to O'Dea's men. Still the issue was in doubt until late in the day, Muirceartach O'Briain unexpectedly arrived at the battle scene and routed the remnants of de Clare's army pursuing them as far as Bunratty. Thus Norman power in Thomond was violently ended thanks mainly to Conor O'Dea and his neighbouring clans.

Upon hearing of the death of her husband and most of his army, de Clare's widow hastily abandoned Bunratty to government control and fled to England with her only son, then a minor. Young Thomas de Clare, the last male representative of his family died in 1321. The de Clare properties in Thomond, now lost to O'Briain control (except Bunratty Castle), were divided between his aunts Matilda, wife of Robert de Welles and Margaret, wife of Bartholemew de Baddlesmere - both wealthy English landowners who did not pursue their seemingly hopeless claims in such a troublesome area as Thomond. Muirceartach O'Brian now had no rival, either Gaelic or Norman, in Thomond and he ruled without opposition until his death in 1343. De Clare's castle of Quin was re-captured and destroyed by the McNamaras in 1320, while Bunratty castle, reputedly burnt in 1318 by de Clare's widow, was captured and demolished by Muirceartach O'Brian and the McNamaras in 1322. Eventhough Bunratty was re-built by the Norman justiciar, Sir Thomas de Rokeby, in 1353 it was levelled again by the O'Briain in 1355. From that date until the submission of Murrough O'Briain, King of Thomond, to Henry VIII at Dublin in 1534, Thomond was ruled by the O'Briain. Under de Muscgregos's and later de Clare's, the manor of Bunratty, comprising some of the best lands in the county, was the centre of Norman power and wealth in Thomond from 1248 until 1318. After the defeat at Dysart O'Dea in 1318 the Anglo-Normans never revived the colony at Tradree. Anglo-Norman government in Ireland had been paralysed by the Bruce invasion of 1315-18, and it was further weakened by the Black Death of 1349-50 with high mortality rates especially in towns and cities which were mainly controlled by the Normans. The Norman economy also declined in the fourteenth century as trade and commerce was reduced by wars, bad harvests and famines. The Hundred Years' War between France and England and the Wars of the Roses in England further weakened central government interest in Irish affairs. More insidiously though, perhaps, the greatest cause of Anglo-Norman decline was the tendency of leading Norman families to become more Irish than the Irish themselves. All these factors ensured that Thomond remained outside Norman control from c. 1332 until the shiring of the county of Clare in 1570. Today the remains of the Norman castles built by de Muscregos and de Clare can still be seen at Clare Castle, Quin and Bunratty.

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