In 1478, Girolamo supported the Pazzi conspiracy against the Medici family. When this failed, he attempted a territorial expansion against the Duchy of Ferrara which in 1482 became known as the "Salt War". The war caused the cession of Rovigo from Ferrara to Venice, but the Papal States did not obtain any territory. The war resulted in an economic crisis, and Forlì was heavily taxed, whereby Girolamo became unpopular. Eventually he was murdered by the rival in 1488, and his wife Caterina became regent for his son Ottaviano Riario (1479–1523).