Cosimo I de' Medici, Grand Duke of Tuscany
Several fortresses formerly held by the Republic of Siena were acquired by Spain following the latter's demise, by treaty between Philip II of Spain and Cosimo I de' Medici, Grand Duke of Tuscany on , to form what became known as the "Estado de los Presidios". They were held by Spain until the War of the Spanish Succession, when they came under Austrian ownership, and were administered from Naples.