The duchies of Parma and Piacenza had been occupied in 1796 by French troops under Napoleon Bonaparte, and the political situation of the State became extremely confused.
Duke Ferdinand had maintained his throne under French military governors until the Treaty of Aranjuez of 1801, when a general agreement between the House of Bourbon and Napoleon formally decides the cession of the duchy to France in exchange for Tuscany, but the Duke lasts in Parma until he dies in 1802, perhaps by poisoning.
Napoleon was undecided about the future of the duchy, aspiring to a total engagement of the Bourbons in the European wars as his allies.
Even as French laws and administration were gradually introduced, the formal annexation to the French Empire was declared only in 1808 after the outbreak of the conflict against Bourbonic Spain. The duchy was reformed as the département of Taro.
In 1814, the duchies Are restored under Napoleon's Habsburg wife, Marie Louise, who rules them for the rest of her life.
After Marie Louise's death in 1847, the Duchy is restored to the Bourbon-Parma line, which had been ruling the tiny Duchy of Lucca.
In this context, Guastalla is ceded to Modena.
The Bourbons rule until 1859, when they were driven out by a revolution following the French and Sardinian victory in the war against Austria (called Austrian War in France and Second War of Independence in Italy).
The Duchy of Parma and Piacenza join with the Grand Duchy of Tuscany and the Duchy of Modena to form the United Provinces of Central Italy in December 1859.
