From An Illustrated History of Ireland by Margaret Anne Cusack
« start... Chapter XIII. ...continued
When the kings had united their forces, they obtained another important victory at Glen-Mama. Harolt, son of Olaf Cuaran, the then Danish king, was slain, and four thousand of his followers perished with him. The victorious army marched at once to Dublin. Here they obtained spoils of great value, and made many slaves and captives. According to some accounts, Brian remained in Dublin until the feast of St. Brigid (February 1st); other annalists say he only remained from Great Christmas to Little Christmas. Meanwhile there can be but little doubt that Brian had in view the acquisition of the right to be called sole monarch of Ireland. It is a blot on an otherwise noble character—an ugly spot in a picture of more than ordinary interest. Sitric, another son of Olaf's, fled for protection to Aedh and Eochaidh, two northern chieftains; but they gave him up, from motives of fear or policy to Brian's soldiers, and after due submission he was restored to his former position. Brian then gave his daughter in marriage to Sitric, and completed the family alliance by espousing Sitric's mother, Gormflaith, a lady of rather remarkable character, who had been divorced from her second husband, Malachy. Brian now proceeded to depose Malachy. The account of this important transaction is given in so varied a manner by different writers, that it seems almost impossible to ascertain the truth. The southern annalists are loud in their assertions of the incapacity of the reigning monarch, and would have it believed that Brian only yielded to the urgent entreaties of his countrymen in accepting the proffered crown. But the warlike exploits of Malachy have been too faithfully recorded to leave any doubt as to his prowess in the field: and we may probably class the regret of his opponent in accepting his position, with similar protestations made under circumstances in which such regret was as little likely to be real.
The poet Moore, with evident partiality for the subject of his song, declares that the magnanimous character of Malachy was the real ground of peace under such provocation, and that he submitted to the encroachments of his rival rather from motives of disinterested desire for his country's welfare, than from any reluctance or inability to fight his own battle.
 Glen-Mama,—The Glen of the Gap, near Dunlavin. This was the ancient stronghold of the kings of Leinster in Wicklow. There is a long and very interesting note on the locality, by the Rev. J. F .Shearman, R.C.C., in the "Introduction" to the Wars of the Gaedhil. He mentions that pits have been discovered even recently, containing the remains of the slain.