These churches, with whatever town may have been connected with them, were plundered by the Danes as early as the year 812; and there is every reason to believe that they fortified the island in the Shannon, or what is now called the English town, with walls and towers very shortly afterwards, as our annalists record the predatory devastations of the Danes of Limerick in Connaught and Meath as early as the year 843, as well as at various years subsequent. They were, however, at length conquered, but not removed, by the victorious arms of Brian Boru, and afterwards Limerick appears in history only as an Irish city, though its inhabitants were chiefly of Danish descent. It was here that Turlogh O’Brien, king of Munster, received in 1064 the homage of Donlevy, king of Ulidia; and his son and successor, Murtogh O’Brien, having given Cashel, the ancient metropolis of Munster, to the church, made Limerick his chief residence and the capital of the province, from which time it continued to be the seat of the kings of Thomond or North Munster, who were hence called kings of Limerick until its final conquest by the English in the commencement of the thirteenth century.
But though thus relieved from the terrors of foreign aggression, Limerick was not secured from the equally sanguinary attacks of the Irish themselves; and our annalists record the burning of the city by Dermod Mac Murrogh in 1014, the very year after the death of Brian, and again in 1088 by Donnell Mac Loughlin, king of Aileach, or the Northern Hy Niall. It was besieged in 1157 by Murtogh, the son of Niall Mac Loughlin, at the head of the forces of the North and of Leinster, when the Danish inhabitants were forced to renounce the authority of Turlogh O’Brien, and to banish him east of the Shannon; and though he was soon after restored to a moiety of his principality, he was obliged in 1160 to give hostages to Roderic O’Conor, to escape his vengeance.
Thus weakened and harassed by the intestine divisions which so fearfully increased in Ireland after the successful and splendid usurpation of the supreme monarchy by their ancestor Brian Boru, it should not be wondered at if the kings of Limerick had made but a feeble resistance to the enthusiastic and disciplined bravery of the Anglo-Norman adventurers, or that their city should have been easily won and as easily kept by these bold warriors; and yet it was not till after many towns of greater importance, if not strength, had been taken by them and securely held, that Limerick ceased to acknowledge its ancient lords as masters. Its king, Donnell O’Brien, was indeed one of the first of the Irish princes, who, forsaking the Irish monarch after the arrival of Strongbow, leagued himself with the English in support of Mac Murrogh, whose daughter, the half sister of the Earl’s wife, he had married; and as a reward for his defection, the king of Limerick claimed the assistance of Strongbow in attacking the king of Ossory. The result of this request is so honourable to the character of one of the Norman chiefs, and is so graphically sketched by Maurice Regan, the king of Leinster’s secretary, that we are tempted to relate it in his own words, as translated by Sir George Carew.