king of Connaught and from 1121 the most powerful Irish prince. In 1118 he divided Munster into two coequal kingdoms; in 1125 he deposed the king of Meath and appointed three kings in his stead; in 1126 he made his son Conchobar king of Dublin and Leinster; and in 1129 he built Ireland's first castle, on the River Shannon at Athlone.