The Duke of Parma (Italian: duca di Parma) was the ruler of the Duchy of Parma, a small historical state of north Italy, which existed between 1545 and 1802, and again from 1814 to 1859. The Duke of Parma was also Duke of Piacenza, except for the first years of the rule of Ottavio Farnese (1549–1556), and the time of the Napoleonic wars, when the two were established as separate positions held by two different individuals. The Duke of Parma also usually held the title of Duke of Guastalla from 1746 (when Francis I, Holy Roman Emperor occupied the Duchy of Guastalla after the last Gonzaga duke died childless) until 1847 (when the territory was ceded to Modena), except for the Napoleonic era, when Napoleon's sister Pauline was briefly Duchess of Guastalla and of Varella. The last duke, Rober