BRIAN (926–1014), king of Ireland, known in Irish writings as Brian Boroimhe (Cogadh Gaedhel re Gallaibh, Rolls Series, p. 208), Boroma ('Tigernachi Annales' in Bodleian MS. Rawlinson B 488), most comonly in earlier books as Brian mac Cennedigh (Book of Leinster, facsimile, fol. 309 a; Tigernach, ed. O'Conor, pp. 266, 268), and in English writings as Bryan mac Kennedy and Brian Boru, was a native of the northern part of Munster, and was of the royal descent of Thomond, of the family known as Dal Cais, who claimed the right of alternate succession to the kingship of Cashel, as the chief kingship of Munster is usually called by the Irish writers. His father was Cenneide, son of Lorcan, and Brian, who was born in 926, was the youngest of three sons. The time of Brian's youth was one of continued harrying of Ireland by the Danes, whose hold on the sea-ports of the country had been steadily increasing since their first invasion in 795, and from Limerick they made many plundering expeditions into the country of the Dal Cais. Brian's elder brother Mathgamhain became head of the tribe, and under him Brian's life as a warrior began ; but when Mathgamhain made peace Brian continued the war by expeditions from the mountains of Clare, but was unable to make way against the Danes, and at last, with only a few followers left, had to take refuge with his brother. The war soon began again, and Mathgamhain succeeded in seizing Cashel and the vacant kingship of Munster. The Danes of Limerick with many native Irish allies marched against the king of Cashel and his brother, and were defeated at Sulcoit in Tipperary. This battle, fought about 968, was the first of Brian's victories over the Danes, and was followed by the sack of Danish Limerick. In 976 a conspiracy of rival chiefs in Munster led to the murder of Mathgamhain, and Brian became chief of the Dal Cais with an abundant inheritance of wars. Succession to the kingship of Cashel was alternate between the Dal Cais and the Eoghanacht, that is between the tribes north of the plain in the middle of which the rock of Cashel rises and those south of it. Maelmuadh, Mathgamhain's murderer, was the next heir of the Eoghanacht, and became king after the murder. Brian defeated and slew him in a pitched battle at Belach Lechta, in the north of the present county Cork, in 978, and thus himself became king of Cashel. He had, however, much hard fighting before he was able to obtain hostages, in proof of submission, from all the tribes of Munster. Constant warfare made the Dal Cais more and more formidable, and having obtained recognition throughout Munster, Brian first led them against Gillapatric, king of Ossory, and then marching into Leinster was, in 984, acknowledged as king by its chiefs. His successes had evidently determined him to extend his sway over as much of Ireland as he could.
Brian sailed up the Shannon from his stronghold at Killaloe, and with varying success ravaged Meath, Connaught, and Breifne, and at length entered into an alliance with Maelsechlainn mac Domhnaill, chief king of Ireland. The Leinstermen with the Danes of Dublin rose against Brian in the year 1000, and, with the help of the king of Ireland, he defeated them with great slaughter at Glenmama in Wicklow, and immediately after marched into Dublin. Sitric the Danish king submitted to Brian, who took a Danish wife and gave an Irish one to Sitric. He now thought himself powerful enough to end his alliance with Maelsechlainn, and sent a body of Danes into Meath towards Tara. Tara had long been an uninhabited green mound, as it is at this day, and its possession was only important from the fact that it was associated with the name of sovereignty and with the actual possession of the rich pastures by which it is surrounded. Maelsechlainn defeated the first force sent against him, but Brian advanced at the head of an army of Munstermen, Leinstermen, Ossorymen, and Danes, and Maelsechlainn retired to his stronghold of Dun na Sciath on Loch Ennell, and sent for help to his natural allies, Aedh, king of Ailech, and Eochaidh, king of Uladh, and to Cathal, king of Connaught ; but all in vain, and he was obliged to offer hostages to Brian. Thus, in the eyes of the Irish, Brian became chief king of Ireland, and the Clonmacnois historian, Tigernach, has at the end of the year 1001 the entry 'Brian Borama regnat' (Bodleian MS. Rawlinson B 488, fol. 15 b, col. ii. line 31). He next made war on the west, received submission from the Connaughtmen, and was thus actual lord of Ireland from the Fews mountains in Armagh southwards. The men of western and central Ulster under the king of Ailech, and those of Dalriada and Dalnaraide under the king of Uladh, still resisted him, but they were also at war with one another, and in 1004 met in battle at Craebh Tulcha and were both slain. Brian at once marched through Meath to Armagh, where he made an offering of gold upon the altar of the great church and acknowledged the ecclesiastical supremacy of Armagh in the only charter of his, the original of which has survived to our day. The charter is in the handwriting of Maolsuthain, Brian's confessor, and is on fol. 16 b of the 'Book of
