the Dál gCais thus did not take part in the Battle of Druim Dearg, which the Gaels lost, damaging the reputation of Thomond as a consequence. Brian Ruadh Ó Briain kept the pressure up by burning Clare Castle and forcing the de Muscregos' to flee to Wales, but he had troubles from his own countrymen. The Mac Con Mara, Ó Deághaidh and Mac Gormáin clans supported his nephew Toirdelbach Ó Briain, a son of Tadhg Cael Uisce, for the kingship instead and revolted. Seeing an opportunity, Edward II offered Thomond to Thomas de Clare if he could take advantage of the Ó Briain feud. The events which followed have passed down to history as the Cathreim Thoirdhealbhaigh. After Brian briefly regained Clonroad with de Clare's help, Toirdelbach arrived with support from Galway in the form of the de Burghs and once again took control in 1277. Brian was executed by his "ally" at Bunratty, but de Clare was soon reconciled with his son Donnchadh mac Brian Ó Briain and supported him against Toirdelbach. The feud continued until Donnchadh drowned at a party on Islandmagrath, on the River Fergus. With Toirdelbach now undisputed king, the Mac Con Mara were able to hound de Clare. The conflict between the two lines continued into the next generation between Donnchadh mac Toirdelbach Ó Briain (backed by William Liath de Burgh) and Diarmuid Cléirech Ó Briain (backed by Richard de Clare). There was military success at Bunratty in 1311 for Diarmuid and his cousin Donnchadh was killed at Corcomroe. Following this, Clann Tadhg's leader was Muircheartach mac Toirdelbach Ó Briain and after Diarmuid's "sudden" death, Clann Briain Ruadh's leader became Donnchadh mac Domhnall Ó Briain. The Bruce Wars in Ireland added an unpredictable element and saw some surprising ad hoc alliances come into play. Donnchadh elected to support Edward the Bruce, which made his patron de Clare an enemy. Muircheartach who now reigned supreme in Thomond, due to his connection to de Burgh, was nominally on the side of the Lordship of Ireland. The cousins fought at the Second Battle of Athenry. Muircheartach's brother Diarmuid mac Toirdelbach Ó Briain managed to destroy Donnchadh and most of Clann Briain Ruadh's supporters at the Battle of Corcomroe in 1317. The end of the de Clares and Norman territorial claims in Thomond came the following year at the Battle of Dysert O'Dea, where Conchobhar Ó Deághaidh held out