"Filia Wilelmi comitis de Burgundia Hermentrudis et filii sui Fridericus, Raginaudus, Theodericus" founded the Cluniac abbey of Froidefontaine by charter dated 8 Mar 1105 in which she names "suis antecessoribus…filiis autem Theoderici atque sue uxoris Hermentrudis, Lodewico, Wilelmo, Hugone". He inherited his families territories along the Meuse valley in 1103. He was expelled by his Meuse subjects in [1113] because of his intolerable behaviour, and transferred to the county of Montbéliard: the Chronicle of Alberic de Trois-Fontaines names "Theodericus" as brother of "Raynaldum…comes Barri et Montionis" specifying that Thierry was expelled in 1113 and retained only the county of Montbéliard.
Comte de Montbéliard. Etienne Bishop of Metz declared that “frater meus Teodericus comes de Montbiliart” recognised the incorrectness of his claims relating to Gorze Abbey by charter dated to [1138/63], naming “cognati nostri Theoderic, Mettensis primicerii”.A charter dated to [1145] confirms the donations to Belchamp abbey by "dominus Theodericus comes de Monte Beligardis", with the consent of "Theoderici filii sui". Humbert Archbishop of Besançon confirmed the foundation of Grâce-Dieu abbey by “dominus Theobaldus de Rubeo Monte et dominus Richardus de Montefalcone...assensu uxorum suarum atque filiorum suorum”, in the presence of “...Theodoricus comes de Monte Belli Cordis...”, by charter dated “V Non Mai” 1147. "Theodericus comes de Monte Biligardis" donated toll revenues to numerous abbeys, after the death of "Theoderici filii mei", by charter dated 1160.
His death, and that of his son, are recorded in 1163 and before 1160 respectively in the necrology of the abbey of Saint-Pierre le Vif, Sens, where their supposed ancestor Louis died [1016/25].
The name of Thierry's wife is not known. 1
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