O'Brien (Ó Briain), Tadhg an Chomhaid

by Emmett O'Byrne

O'Brien (Ó Briain), Tadhg an Chomhaid (d. 1466), king of Thomond, was son of Toirdhealbhach Bog O'Brien, king of Thomond, and Catherine, daughter of Ulick fitz Walter Burke. In 1459 he succeeded his father as king. He maintained his family's close links with the Burkes by marrying Annabella, daughter of Ulick fitz Ulick Burke. One of the most significant events of his early kingship was his erection of the castle of Chomhad in the Burren, which was probably against his rival Donnchadh O'Brien. But after 1461 Tadhg began a systematic programme of conquest east of the Shannon. His success was aided by the four-year tenure of the deputyship of Ireland by Thomas FitzGerald (qv), 8th earl of Desmond, but it was Desmond's defeat at the hands of the O'Connor Falys (1466) that sparked Tadhg's most dramatic advance. Tadhg crossed the Shannon and conquered the Clanwilliam lands of the de Burghs straddling Limerick and Tipperary; he also invaded Desmond because the earl was harbouring a rival branch of O'Briens. Such was Tadhg's strength that he was able to bribe the Irish of Leinster to help by making disturbances. Desmond had little option but to accept O'Brien's conquests, and the county of Limerick was forced to grant him an annual black rent of £40. Tadhg's success was such that he entertained thoughts of reviving the kingship of Tara. Before he could breathe life into his plans, he caught a fever and died before the end of 1466 (though there is a suggestion that he was poisoned). But his successors continued to enjoy his gains, which led directly to the decline of the de Burghs of Clanwilliam in Tipperary and Limerick. This territory became a dependency of the O'Briens from 1466 , becoming a wedge between the lands of the Butlers and Desmond. Tadhg was succeeded by his brother Conchobhar O'Brien (Ó Briain) (1440–96), who consolidated the gains by keeping on good terms with the de Burghs of Clanricard, marrying his daughter Sláine to Uilleag Ruadh Burke (de Burgh) (qv). In 1469 Conchobhar came to the aid of his son-in-law when he was attacked by Aodh Ruadh O'Donnell (qv) of Donegal, but the pair were routed by the invading O'Donnells at the battle of Glanog. In 1470 Conchobhar was quickly back in the saddle, exploiting the disorder caused in the earldom of Desmond by the 1468 execution of the earl, Thomas FitzGerald.

From the middle years of the 1470s Conchobhar began to encounter growing opposition to his rule over Thomond. In 1474 his son Tadhg was killed in a dispute with his cousin Diarmait O'Brien. But it was the eventual emergence of Tadhg an Chomhaid's son, Toirdhealbhach Donn O'Brien (qv), that really threatened Conchobhar's crown. By 1486 Toirdhealbhach had wrested much of east Thomond from Conchobhar's grasp, and he allied himself with the FitzGeralds of Desmond by marrying Eleanor FitzGerald (1490). After this, Conchobhar was largely a figurehead rather than the real power in Thomond. He was succeeded on his death (1496 ) by his brother Toirdhealbhach Óg O'Brien (c.1445–98), who, however, died in 1498, leaving the way open for Toirdhealbhach Donn.