Who married Catherine de' Medici, Governor of Siena?

Caterina de' Medici (2 May 1593 – 1629) was a Tuscan noblewoman of the Medici family. She became Duchess of Mantua and Montferrat as the second wife of Duke Ferdinando and Governor of Siena from 1627. She was the second daughter of Grand Duke Ferdinando I of Tuscany and his wife Christina of Lorraine.

Ferdinand I Gonzaga (26 April 1587 – 29 October 1626) was Duke of Mantua and Duke of Montferrat from 1612 until his death.