He was often both at war and at peace with the foreigners of Cork and Limerick, and did not hesitate more than once to employ their arms for the maintenance of his own supremacy; but his only authentic captivity was, as a hostage, in the hands of Murkertach.

Thorlogh O'Brien, once King of all Munster, refused to accept a mere third, and carrying away his jewels and valuables, including the drinking horn of the great Brian, he threw himself again on the protection of Murkertach of Aileach. The elder branch of the family of O'Melaghlin were equally indisposed to accept half of Meath, where they had claimed the whole from the Shannon to the sea.

While the latter was absent, on his expedition to Insi-Gall, Kellachan fell upon the Deisi and Ossorians, and inflicted severe chastisement upon them-alleging, as his provocation, that they had given hostages to Murkertach, and acknowledged him as Roydamna of all Erin, in contempt of the co-equal rights of Cashel.

Kellachan alone was submitted to the indignity of wearing a fetter. With these distinguished hostages, Murkertach and his leather-cloaked "ten hundred" returned to Aileach, where, for five months, they spent a season of unbounded rejoicing.

In the years 933, at Slieve Behma, in his own Province, Murkertach won a third victory; and in 936, taking political advantage of the result of the great English battle of Brunanburgh, which had so seriously diminished the Danish strength, the Roydamna, in company with the King, assaulted Dublin, expelled its garrison, levelled its fortress, and left the dwellings of the Northmen in ashes.

Murkertach, according to Malmsbury, maintained a close correspondence with Henry I., for whose advice he professed great deference. He was accused of aiding the rebellion of the Montgomerys against that Prince; and if at one time he did so, seems to have abandoned their alliance, when threatened with reprisals on the Irish engaged in peaceful commerce with England.

That winter Magnus spent with Murkertach at Kinkora, and "towards spring both kings went westward with their army all the way to Ulster." This was one of those annual visitations which kings, whose authority was not yet established, were accustomed to make.

In the years 933, at Slieve Behma, in his own Province, Murkertach won a third victory; and in 936, taking political advantage of the result of the great English battle of Brunanburgh, which had so seriously diminished the Danish strength, the Roydamna, in company with the King, assaulted Dublin, expelled its garrison, levelled its fortress, and left the dwellings of the Northmen in ashes.

He was not, like his father, like Murkertach O'Brien, Malachy II., Brian, Murkertach of the leathern cloaks, or Malachy I., eminent as a lawgiver, a soldier, or a popular leader. He does not appear to have inspired love, or awe, or reverence, into those of his own household and patrimony, not to speak of his distant cotemporaries.

He stood at the very summit of his good fortune, when the Danes of Dublin, reinforced from abroad, after his "Circuit," renewed their old plundering practices. They marched north, at the close of winter, under Earl Blacair, their destination evidently being Armagh. Murkertach, with some troops hastily collected, disputed their passage at the ford of Ardee.