He was also styled King of Limerick, a title belonging to the O'Brien dynasty since Brian Boru's sacking of the Hiberno-Norse city state after the Battle of Sulcoit in the 10th century.

Domnall Mór ("Donall the Great") was the third son of Toirdhealbhach mac Diarmada Ua Briain, King of Munster, who reigned from 1142 to 1167.

The same year, Domnall entered into conflict with the High King of Ireland, Ruaidrí Ua Conchobair and was forced to pay him a tribute of 300 cows.

In 1171, he submitted to King Henry II of England at Cashel, but he continued to fight successfully against the Norman incursion into southwest Ireland for many years.

Supported by Robert Fitz-Stephen and Miles de Cogan, the Lord Deputy set out to take possession of Limerick, but on approaching the city, turned back in a panic.