Niall mac Muircheartach Ua Lochlainn, son of the High King had, on a royal heir's feasting visitation... through Leath Cuinn... committed various acts of violence in territories and churches.
Conchobar Maenmaige is next mentioned in the Annals of Ulster in 1174 in the following terse statement: "The battle of Durlus [was gained] by Domnall Ua Briain and by Conchobur Maenmhaighi upon the people of the son of the Empress (namely, of the king of the Saxons)."
In 1184 the King of Meath, Art Ua Melaghlin, "was treacherously slain by Dermot O' Brien (i.e. the son of Turlough), at the instigation of the English".
The armies of Connacht and Meath, led by both men, attacked and destroyed castles in areas conquered by the invaders, the result being "many of the English were slain".
Reconciled, Conchobair and Cathal Carragh burned Killaloe, as well churches as houses, and carried off all the jewels and riches of the inhabitants ... [left Thomond] ... destroyed and pillaged.
Two years later it was Connacht's turn to be on the receiving end, as John de Courcy led a Norman incursion into the province, accompanied by Conor mac Cormac.
Conchobar roused the Connacht chieftains, and was joined by his paternal 1st cousin, Donnell Mor Ua Brian, King of Thomond.
Forced back, the English were returning by way of the Curlew Mountains where they were attacked by the Connacians and Momonians... those who survived retreated with difficulty from the country, without effecting much destruction on this incursion.
Mac Carthy, King of Desmond, was in his house, and Ó Conor gave him a great stipend, namely, five horses out of every cantred in Connacht.