THIERRY de Mousson, son of THIERRY de Mousson & his wife Ermentrude de Bourgogne [Comté] ([1076/78]-[mid-Jan] 1163). "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"[1568]. 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[1569]. 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"[1570]. 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"[1571]. "Theodericus comes de Monte Biligardis" donated toll revenues to numerous abbeys, after the death of "Theoderici filii mei", by charter dated 1160[1572]. 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][1573].
m ---. The name of Thierry's wife is not known