Ua Conchobair, Tairdelbach (O'Conor, Turlough) (1088–1156), king of Connacht and high-king of Ireland ‘with opposition’. His accession to the kingship of Connacht in 1106, and his domination of that province for the next half-century, saw the emergence of Connacht as a major political power for the first time since the seventh century. During his reign he transformed Connacht and consolidated his family's position (and that of his ecclesiastical allies) by a series of innovative military and political moves that included the construction of numerous fortresses (caisdeoil), a substantial naval fleet, and the physical relocation of his power-base to the heartland of Connacht around the plain of Mag Seóla (Co. Roscommon). This had been the traditional territory of the rival Ua Flaithbertaig dynasty (which he expelled), with its ecclesiastical headquarters in the archiepiscopal city of Tuam (Co. Galway), for the bishop of which he commissioned the superb processional Cross of Cong, manufactured between 1123 and 1127, one of the finest examples of twelfth-century Irish ecclesiastical metalwork, and believed to contain a relic of the True Cross. It was a striking demonstration of Tairdelbach's close relations with the church, and his ambitions for the diocese of Tuam. He established his capital at the fortress of Dunmore (Co. Galway), and constructed fortresses and fieldworks also at Westport (Co. Mayo), at Collooney (Co. Sligo), and at Dunamon, on the River Suck, for the purposes of which he undertook major engineering works to divert the course of the river in order to provide a defensive barrier against his enemies in Uí Maine. He constructed further castles at Athlone and Ballinasloe, as well as several bridges across the Shannon.
The Síl Muiredaig sept from which Tairdelbach descended had suffered at the hands of Munster kings in the years before he came to prominence, and he himself had become king in 1106 with the connivance of Muirchertach Ua Briain (qv), king of Munster. It was only in 1114, with the ousting of Ua Briain, that Tairdelbach succeeded in establishing his own autonomy. By siding in that year with the northern king Domnall Ua Lochlainn (qv) against Ua Briain in a military campaign that saw Munster invaded, Tairdelbach effectively cut the ties with Munster. However, by agreeing terms with Ua Briain, and thereby neutralising the expedition before it could be concluded, Tairdelbach cleverly outmanoeuvred Ua Lochlainn. From that point on he was a serious contender for the high-kingship of Ireland.
Tairdelbach's subsequent career can be divided into three phases: 1) from 1115 to 1131 his campaigns were directed against the power of Munster; 2) from 1131 to 1140 he suffered reaction from his enemies, who combined against him; and 3) from 1140 to his death in 1156 he faced growing opposition from his great northern rival, Muirchertach Mac Lochlainn (qv), king of Cenél nÉogain. During all these years Tairdelbach demonstrated a truly remarkable energy and enterprise, and of all the Irish kings he was the most effective military commander and the most innovative strategist and tactician. Others before him had utilised fortifications to a degree; Tairdelbach constructed an entire system of earthwork defences and castles to provide a frontier defence for Connacht. Admittedly these were usually built of wood, and therefore easily destroyed by his enemies. But he rebuilt them when required, and used them imaginatively in his campaigns, as he did ships and bridges. He utilised substantial numbers of warships on all his expeditions along the entire length of the coast, from Cork Harbour as far north as Tory Island in the far north-west. His most striking victory was won in 1154, not long before his death, when the Connacht naval force utterly destroyed the fleet hired by Mac Lochlainn from the Norse kingdom of the Isles and of Man. A new military terminology appears in Irish historical sources during his years, a clear indication of his lasting legacy in that area.
Tairdelbach's political strategy involved a combination of straightforward military campaigning with divide-and-conquer tactics amongst his defeated rivals. Thus in 1114, after internecine struggles had seen Muirchertach Ua Briain ousted from the Munster kingship, he set up the rival Éoganacht dynasty of Cashel as puppet Munster kings and granted them the southern half of the province (Desmond). He then took advantage of Munster's temporary weakness to invade Leinster (previously under Munster domination), expelled the Munster satrap ruler of Dublin, and granted it to Énna Mac Murchada (older brother of Diarmait Mac Murchada (qv), known to history as ‘Diarmait na nGall’: Diarmait of the foreigners). Mac Murchada in turn made submission to Tairdelbach, and handed over hostages. In 1118 Tairdelbach led a huge army into Munster, demolished Ua Briain's royal residence at Kincora, and hurled it into the Shannon. Muirchertach Ua Briain's death in 1119 left Munster powerless to resist: in the next few years Tairdelbach plundered the province with such severity that a contemporary annalist reported that he ‘caused Munster to cry aloud’.
By the mid 1120s, however, Tairdelbach's relentless aggression had forged an alliance of his rivals in Bréifne, Meath, and Leinster which had the support of the king of Munster; together they marched against Connacht. Tairdelbach, however, contrived to hold the bridge at Athlone, he executed several of their hostages, and forced their retreat. In 1125 he dealt with each of his rivals in turn. The death in early 1126 of Énna Mac Murchada in Leinster left that province without effective leadership (Énna's brother Diarmait may have come to power at that time), and Tairdelbach used the opportunity to reduce the province to submission and impose his own son Conchobar (qv), first as ruler of Dublin and then as king of Leinster. The death of Domnall Ua Lochlainn in 1121 had left Tairdelbach as undisputed ruler of Ireland, but by 1131 Connacht was being invaded again from two directions simultaneously. His fleet was defeated on the west coast, his castles at Galway and elsewhere being seized and destroyed. Only a truce engineered through the intervention of the church in 1133 saved him from utter destruction.
But whereas external opposition and internal rivalries appeared to have done for Tairdelbach, he re-emerged in 1138 and staged a dramatic comeback. In 1140 he took the offensive once more, throwing a bridge across the Shannon and invading Meath. Though parried initially by the Munster king, Tairdelbach Ua Briain (qv) (d. 1167), Tairdelbach succeeded in stringing together a temporary alliance that saw him re-establish some control over Meath and Leinster. In 1144, however, the Meathmen assassinated his son Cochobar, who had been imposed on them by Tairdelbach; the result was a terrible vengeance in which he inflicted frightful slaughter on them ‘like unto the day of judgement’.
Following his defeat of the Meathmen, Tairdelbach again imposed his policy of divide-and-rule, partitioning the kingdom amongst its traditional internal rivals, as he did also in Leinster. A temporary truce with Munster, brokered by the church at Terryglass in 1144, proved short-lived. The emergence in 1145 of Muirchertach Mac Lochlainn as another northern rival presented Tairdelbach with his most serious challenge to date: to stave off an inevitable invasion of Connacht, in 1150 he recognised Mac Lochlainn as high-king. The disastrous battle of Móin Mór (1151) saw the end of Ua Briain political power in Munster for a generation; in the vacuum that ensued, Tairdelbach again saw his opportunity for self-advancement. Tairdelbach and Mac Lochlainn met in conference at Belleek, Co. Fermanagh, in 1152 and concluded a peace treaty, as a result of which the two joined forces, together with Mac Murchada of Leinster, against Meath and the rising ambitions of Tigernán Ua Ruairc (qv) in Bréifne. The abduction of Ua Ruairc's wife by Mac Murchada was to have momentous consequences (at least in legend), but the immediate result of the campaign was the re-establishment of Tairdelbach as the chief rival to Mac Lochlainn. Mac Lochlainn, realising that fact, marched against Connacht, and penetrated as far as Tairdelbach's castle at Dunamon, razing it to the ground, before marching to Dublin in order to secure the submission of that vitally important city. The death in 1155 of the king of Meath gave Tairdelbach yet another opportunity to build up an alliance against Mac Lochlainn, but his own death in the early summer of 1156, in his fortress at Dunmore, brought an end to his remarkable career.
The rise of Connacht in the second half of the twelfth century to become a major power was one of the greatest surprises in Irish history, and was due in large part to Tairdelbach's singular ability. Since the seventh century the province had been regarded as a backwater in Irish politics, and the rise of the Ua Conchobair is not easy to account for. Tairdelbach's only major political fault was his failure to realise the vital economic importance of Dublin to any would-be claimant to the high-kingship. In everything else he proved himself a master of military strategy and a political animal of ability as well as ambition.