Complex sentence: 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 individuals.
Split into simpler sentences: 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. Dukes of Parma and Piacenza, when the two were established as separate positions held by two individuals.