The Constitution of the principality was written by Napoleon on 22 June (1805), establishing a Council of State to assist the princess and a legislative Senate.

Henceforth the Principality of Lucca and Piombino became part of the Grand Duchy of Tuscany, and consequently a territory of the First French Empire.

In 1814, the Imperial Austrian Army occupied Lucca, ending French control with the fall of Napoleon.

The Congress of Vienna (1814–1815) bestowed the duchy upon the Infanta of Spain Maria Louisa, erstwhile Queen of Etruria and the matriarch of the House of Bourbon-Parma.

This was a form of compensation for not having returned their Duchy of Parma to them and instead having granted it to Napoleon's wife, Marie-Louise of Habsburg-Lorraine.