Made colonel then major-general, he fought in the subsequent German campaign at the battles of Lützen, Dresden, Kulm and Leipzig. In September that year he was sent on a mission to convince Napoleon's former Marshal, and Swedish Crown Prince Jean Baptiste Bernadotte, later King Charles XIV John of Sweden, to move his Army of the North across the Elbe to engage Napoleon's forces. At the start of 1814 he crossed the Rhine with the Russian army, setting foot in France for the first time in 10 years. He came into contact with the future Louis XVIII and Charles X and participated in the creation of a royalist party. His brother Louis, with whom he had shared many hardships, was killed at Brienne and so he became head of the House of Rochechouart. Louis-Victor-Léon fought in the Six Days Campaign and the battles of Arcis-sur-Aube, La Fère-Champenoise and Paris. Made commander of Paris, he captured the Hotel de Ville on 31 March. Face with rumours of a counter-attack by Napoleon, he organised the city's defences and then restored order in Paris, facing down the troubles provoked by the occupying troops by deploying mixed bodies of men consisting of both Russian and National Guard troops. On Louis XVIII's arrival on 20 April Rochechouart took leave of the Russian army to offer Louis his services.