Tadhg expelled Gilbert and allied with Ruaidhri, who assembled the men of Connacht and Brefne, together with many gallowglasses, and penetrated to the midst of Sil Murray and the rest of Connacht, and forthwith burned the town of Sligo, Ballymote, the great castle of Kilcolman, Ballintober, Dunamon with its castle, Roscommon, Randoon and Athlone, as well as all the houses which lay on his route ... he took pledges and hostages of the rest of the Sil Murray and was made king on Carnfree.
Tadhg accompanied Ruaidhri on his subsequent winter raids around Connacht, such as those at Leith Luigne and the slopes of Sliab Gam, and in particular to Glenn Fathraim, where they killed many thousand cows and sheep and horses.
At that time they stripped women and ruined children and lowly folk, and never within the memory of man were so many cattle, fruitlessly destroyed in one place.
As a result, both of the warfare and severe climatic conditions, "Many afflictions in all parts of Ireland: very many deaths, famine and many strange diseases, murders, and intolerable storms as well."
Tadhg now accompanied Fedlim, “the traitor” who switched sides and proceeded to wage war against his former allies, the Anglo-Irish of Connacht.
Tadhg's head, along with that of King Fedlim, was surmounted on the twin towers of the main gate of Athenry, as the most dangerous of the defeated Irish.