House of Savoy-Carignano

[2] The fief of Carignano had belonged to the Savoys since 1418, and the fact that it was part of the Principality of Piedmont, only twenty kilometers south of Turin, meant that it could be a princedom for Thomas in name only, being endowed neither with independence nor revenues of substance.

[3] Instead of receiving a significant patrimony, Thomas was wed in 1625 to Marie de Bourbon, sister and co-heiress of Louis, Count of Soissons, who would be killed in 1641 while fomenting rebellion against Cardinal Richelieu.

It was arranged that Thomas Francis, as son of a reigning monarch, would hold the rank of first among the princes étrangers at the French court—taking precedence even before the formerly all-powerful House of Guise, whose kinship to the sovereign Duke of Lorraine was more remote.

Marie eventually inherited her brother's main holding in France, the county of Soissons; this would be established as a secundogeniture for the French branch of the family.

He managed to rally the remnants at Namur, then retreated before the numerically superior French and Dutch forces, and he probably served the rest of the campaign with Ferdinand.

The invasion was initially very successful, and seemed capable of reaching Paris, where there was a great panic; if Ferdinand and Thomas had pushed on, they might have ended the war at this point.

In 1645, now commanding with du Plessis Praslin, he took Vigevano, and repulsed a Spanish attempt to block his withdrawal at the River Mora, the nearest he ever came to a success in the field.

In 1646, Thomas Francis was put in command of the French expedition sent south to take the Tuscan forts, after which he was to advance further south to Naples, drive out the Spanish and put himself on the throne of the kingdom; but the expedition set off late, and when he besieged Orbetello, the supporting French fleet was defeated by the Spanish and he was forced to raise the siege and conduct a difficult retreat, which he performed poorly.

During the Fronde, Thomas Francis linked himself closely with Cardinal Mazarin who, although effectively chief minister of France, was like him an Italian outsider at the French court.

In the early 1650s, Thomas Francis was seen as an important member of Mazarin's party, closely linked to the Cardinal, regularly seen in conference with him, and active in his support.

The Franco-Spanish war had been continuing in north Italy, and late in 1654 the increasing Savoyard hostility to the current French commander Grancey led to a search for a new allied commander-in-chief; the French would have preferred to send the Duke of York (later King James II); as he was unacceptable to Turin, Thomas Francis was appointed as joint commander, akthough his wife was held in France almost as a hostage for his good behaviour.