Montholon had to spend many years in what is now Belgium, and in 1840 acted as "chief of staff" in the absurd "expedition" conducted by Louis Napoleon from London to Boulogne. He was condemned to imprisonment at Ham, but was released in 1847 thanks to the efforts of Gourgaud, who was then in favour with the administration; he then retired to England and published "Récits de la captivité de l'Empereur Napoléon à Sainte-Hélène". In 1849, he became one of the deputies for the Legislative Assembly under the Second French Republic. He lived to see the establishment of the Second French Empire in 1852.