In 1806, in the reorganization of Germany occasioned by the dissolution of the Holy Roman Empire, Maximilian I Joseph, now King of Bavaria, ceded Berg to Napoleon in return for the Principality of Ansbach.

On 15 March 1806, the French emperor put Berg under the rule of his brother-in-law Joachim Murat, including territories of the former Prussian Duchy of Cleves east of the Rhine river.

His lands were further enlarged by the annexation of the County of Mark, the Prince-Bishopric of Münster, the Imperial city of Dortmund and numerous minor territories of the Lower Rhenish-Westphalian Circle.

The state was in constant economic decline ever since its formation, this is in large part due to Napoleon's failed Continental System which led to a series of revolts and uprisings.

The grand duchy's short existence came to an end when the French forces pulled back in the course of the German campaign of 1813.