He is chiefly remembered for his role in advocating for Frenchman Jean Baptiste Bernadotte's succession to the Swedish crown in 1810.

Although the Swedish government, amazed at Mörner's effrontery, placed him under arrest, the candidature of Bernadotte gradually gained favor.

On 21 August 1810 in Örebro, Bernadotte was elected by the Riksdag of the Estates to be the new Crown Prince, and was subsequently made Generalissimus of the Swedish Armed Forces by the King, Charles XIII.

He was deputy governor of Jämtland from 1824, until he was appointed customs inspector at Blockhusudden in 1829, remaining in that office until he retired in 1841.

The film tells a fictionalized story of Désirée Clary, spouse of Charles XIV of Sweden, and her relationship with Napoleon.