(1088–1156), high king of Ireland. Toirdelbach became king of Connacht in 1106 and rose to national importance following the fall from power of Muirchertach Ua Briain in 1114. He spent the period to 1131 asserting power over the other provinces, then suffered setbacks, began to reassert himself in 1138, and from then until 1150, when Muirchertach Mac Lochlainn began to challenge him for the position, was widely recognized as king of Ireland. He was an innovatory military commander and his reign is notable for the use he made of naval forces and for the construction of castles and bridges. He deposed other provincial kings and partitioned their kingdoms, and his favourite son Conchobar (d. 1143) was appointed at various stages king of Dublin, Leinster, and Meath. He died in 1156, aged 68, at his fortress at Dunmore, Co. Galway, was buried in Clonmacnoise, and was succeeded by his son Rory O'Connor.
From The Oxford Companion to Irish History in Oxford Reference.
Subjects: European History.