He was king of Connacht with opposition from 1189 to 1202 with
Cathal Carragh Ua Conchobair, son of the previous king
Conchobar Maenmaige Ua Conchobair, Crobhdearg's nephew. In 1190 a meeting was held at
Clonfert to try and establish peace between the two claimants but was unsuccessful. Crobhdearg narrowly escaped drowning soon after when his ship was wrecked in a storm on
Lough Ree, himself and six others being the only survivors, thirty-six others perishing. In 1195 he led a hosting into Munster destroying several castles and towns. He founded
Ballintubber Abbey in 1216. His wife,
Mór Ní Briain, a daughter of king
Domnall Mór Ua Briain of
Thomond, died in 1218. He died in the same year and was succeeded by his son,
Aedh mac Cathal Crobdearg Ua Conchobair ''''for he had been king by the side of his father (rí ri láim a athar) and already held all the hostages of Connacht. And God granted him this kingdom, for no crime was committed in Connacht at the moment of his accession save one robbery on the road to Cruach, and the hands and feet of the robber were cut off, and the violation of one woman by O Mannachan's son, who was blinded forthwith for the offence.'''' The
Annals of Connacht give his death obit as, •
The King most feared and dreaded on every hand in Ireland, the king who carried out most plunderings and burnings against Galls and Gaels who opposed him, the king who was the fiercest and harshest towards his enemies that ever lived; the king who most blinded, killed and mutilated rebellious and disaffected subjects; the king who best established peace and tranquility of all the kings of Ireland; the king who built most monasteries and houses for religious communities; the king who most comforted clerks and poor men with food and fire on the floor of his own habitation; the king whom of all the kings in Ireland God made most perfect in every good quality; the king on whom God most bestowed fruit and increase in crops; the king who kept himself to one consort and practiced continence before God from her death till his own; the king whose wealth was partaken by laymen and clerics, infirm men, women and helpless folk, as had been prophesied in the writings and the visions of saints and righteous men of old, the king who suffered most mischances in his reign, but God raised him up from each in turn; the king who with manly valour and by the strength of his hand preserved his kingship and rule. And it is in the time of this king that tithes were first levied for God in Ireland. This righteous and upright king, this prudent, pious, just champion, died in the robe of a Grey Monk, after a victory over the world and the devil, in the monastery of Knockmoy, which with the land belonging to it he had himself offered to God and the monks, on the twenty-seventh day of May as regards the solar month and on a Monday as regards the week-day, and was nobly and honourably buried, having been for six and thirty years sole monarch of the province of Connacht. ==Inauguration==