in a surprising turn of events, in 1151, o brian was deposed as king of munster by his son, muircheartach. muircheartach was subsequently captured ""by treachery"" by ""tadhg son of diarmaid o brian and diarmaid súgach o conchobhair"" and delivered to his father. however, tadhg mac diarmaid o brian rose against o brian in rebellion, with the result that ""toirdhealbhach son of ruaidhrí o conchobhair came with him to defend the kingship of munster for him.""!