The principals and Madamists were the two factions that fought power over the Savoy Duchy after the death of Duke Vittorio Amedeo I in 1637, during the Thirty Years' War, involving the Duchy in hostilities between France and Spain.

The Madamists, French-speaking, supported the Duke's widow, the "royal Madame" Maria Cristina, sister of King Louis XIII of France and regent of the Duchy of children, first Francis Giacinto (until his death in 1638) then Carlo Emanuele II. The principals, spanish-spaniards, supported the brothers of the deceased dean, Thomas of Savoy, prince of Carignano, and Cardinal Mauritius, who fled to Spain and opposed the regency of their sister-in-law.

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