Toirdhealbhach Mór Ua Conchobhair (old spelling: Tairrdelbach Mór Ua Conchobair; 1088 – 1156) anglicised Turlough Mór O'Conor, was King of Connacht (1106–1156) and High King of Ireland (ca. 1120–1156).
Family background and early life
Toirdelbhach was born in the year 1088. He was the youngest son of Ruaidrí na Saide Buide (died 1118), and his mother was Mór, daughter of Toirdelbach Ua Briain (1009–14 July 1086). Therefore, through his mother, his great-great-grandfather was Brian Boru. His brothers were Niall (killed 1093), Tadc (killed 1097), Conchobar (murdered 1103), and Domnall, King of Connacht (deposed 1106). There was at least one sister, Dubhchobhlaigh Bean Ua hEaghra of Luighne Connacht (died 1131). Ruaidrí was married to four or more women.
According to the Annals of Tigernach, Toirdelbach's mother died the year he was born, suggesting his birth may have been arduous. In 1092, King Ruaidrí was blinded by Flaithbertaigh Ua Flaithbertaigh, an incident which led to the domination of Connacht by the Dál gCais of Munster, led by Tairrdelbach's uncle, the brother of Tairrdelbach's mother, Muirchertach Ua Briain, High King of Ireland, who possibly took Tairrdelbach into his household to groom him for the day when he would be king of Connacht. (p. 471,MIAE 2005)
However this would not occur until 1106; until then, Connacht endured a prolonged period of civil strife between different factions of the Uí Conchobair, Uí Ruairc of Bréifne as well as more minor families of the Uí Briúin and Síol Muireadaigh, including the long-displaced Ui Fiachrach Aidhne. Tairrdelbach's brothers Tadc and Domnall both gained the kingship at different times, but depended upon the support of Muircherteach Ua Briain.
Early reign
thumb|The [[Cross of Cong, a reliquary and processional cross that contains a piece of the True Cross, was commissioned by Toirdelbach and made at Roscommon.]]
In 1106, with the support of his uncle Muirchertach Ua Briain, eighteen-year-old Tairrdelbach deprived his older brother Domnall of the kingship of Connacht. <blockquote>"Tairrdelbach carefully maintained his alliance with Ua Briain, sending troops to aid the High King against the Ui Ruaric of Bréifne in 1109. But he was also determined to defend his kingdom against predators such as Domnall Mac Lochlainn of the Uí Néill (d. 1121), king of the north of Ireland."</blockquote>
In 1110, Mac Lochlainn raided Connacht, carrying off herds of cattle and captives. While this raid rattled Toirdelbach, he demonstrated that he was not weak by attacking the Conmaicne and Breifne, with mixed fortunes; he defeated the former at Mag Na, but his army was defeated by the men of Breifne at Mag Brenair. He attacked the Northern Uí Néill the next year in 1111, plundering Termonn Dabeoc in Tír Chonaill and ravaging modern County Fermanagh as far as Lough Erne.
Domnall, Toirdelbach's brother who he had taken the Kingship of Connacht from would remain in Connacht, however, and contested Toirdelbach's claim to the throne of the Kingdom, but he was finally expelled southward to Munster by Toirdelbhach several years later in 1114. A year later in 1115, an attempt to assassinate him was made by some of his nobles who were discontent with his rule at Ath Bo, but they were unsuccessful.
Although much of his time and resources during his early reign were spent in Munster, he was also involved in campaigns elsewhere. In 1115, his wife Orlaith of the Kingdom of Meath died, ending the alliance between Toirdelbach and Murchad Ia Mael Sechnaill, King of Meath. Toirdelbach defeated their forces on both land and on the River Shannon, gaining the submission of Meath. He later married Connacht noblewoman Cailleach De, daughter of Ua hEidin, who was the mother of future High King Ruaidrí Ua Conchobair, Toirdelbach's son. At the end of 1115, he bestowed gifts upon the church at the monastery at Clonmacaoise, including a drinking horn and chalice.
A tactic Toirdelbhach used throughout his career in politics and as High King was divide and rule. This can be seen in several instances, most notably the partition of Munster, which at the time, under the rule of the Ua Briain (O'Brien dynasty) was the most powerful kingdom in Ireland and had controlled the High Kingship for over a century, since the death of Brian Boru.
Partition and war in Munster
In 1114, Toirdelbhach took advantage of political turmoil in the Kingdom of Munster, which at the time was ruled by his uncle, Muircherteach Ua Briain, King of Munster and High King of Ireland, who had previously often supported Toirdelbach as he reigned in Connacht and was the one who backed him to take the Kingship from his brother, had become "sick to the point of a living Skeleton". It was at this point that Diarmuid, brother of Muircherteach, took the Kingship and banished Muircherteach.
He also created a new supply of water for settlements in eastern Connacht when he constructed a six-mile-long canal which redirected the River Suck around a castle and towards nearby towns and villages. The route of this damn probably began near the modern town of Ballinasloe which was built on the river later.
A political strategy often utilised successfully by Toirdelbhach was the appointment of relatives or loyal nobles as rulers or governors of towns, cities and other lesser regions or kingdoms. This allowed him to keep control of every area in the country and avoid rebellions or alliances against him.
The Northern Uí Néill were alarmed by these attacks on the province of Ulster and decided to take action to assist the O'Donnells. Muircherteach Mac Lochlainn (who would later succeed Toirdelbach as High King of Ireland), who was a member of the Cenel Eoghain branch of the Ui Néill Dynasty, decided to request the assistance of the Viking Norse-Gaels who inhabited the Norse Kingdom of the Isles in the modern Hebrides and Western Isles of Scotland.