During the First War of Castro, Savelli was given the title of "Generalissimo" and was put in command of a contingent of papal troops fighting the Dukes of Parma. However, according to contemporary John Bargrave, Savelli had great respect for the Dukes and also believed Pope Urban VIII would not live long and so the war was futile. As a result, Savelli moved his troops slowly and was hesitant to engage in battle. Pope Urban relieved Savelli of his command and appointed his nephew, Taddeo Barberini, in Savelli's place.