Thirty Years War

Italy

Montferrat and its fortress of Casale Monferrato were subsidiary territories of the Duchy of Mantua and their possession allowed the holder to threaten Milan. When the Duke of Mantua died in December 1627, France and Spain backed rival claimants, resulting in the 1628 to 1631 War of the Mantuan Succession. The French-born Duke of Nevers was backed by France and the Republic of Venice, his rival the Duke of Guastalla by Spain, Ferdinand II, Savoy and Tuscany. While a relatively minor conflict, the struggle had a disproportionate impact on the Thirty Years War, since Pope Urban VIII viewed Habsburg expansion in Italy as a threat to the Papal States. His opposition to Ferdinand II divided the Catholic powers, and made it acceptable for France to employ Protestant allies against Austria.