While Thomas hoped to stay with her at the French court, the king's mother, Blanche of Castile, wanted greater control over the new queen, and so dismissed all who came with her before the couple even reached Paris.

He returned to visit the family around Easter of 1240 and was given a gift which Henry III of England extracted from the lands of Simon de Montfort.

[5] In July 1243, Thomas and his brother Amadeus were ordered by Enzo of Sardinia to join in a siege of Vercelli, which had recently switched allegiances from the Empire to the Pope.

[6] When the brothers wrote to the new Pope Innocent IV to appeal, he granted their request, and further indicated that Thomas would be protected from excommunication without papal authorization.

In response, Pope Alexander IV placed an interdict against Turin and Asti, and King Henry III of England imprisoned all Lombards in his kingdom.

Thomas's brothers, Peter and Philip led an army down from Savoy in 1256, and were able to force a negotiated settlement by the end of the year.

[8] Although he was the next brother of Amadeus IV, he never became the Count of Savoy because he predeceased his nephew, Boniface, who himself died without sons to succeed him.