The Crimean War was an opportunity for France to try to extend its allegedly insufficient economic exchanges with the Danubian principalities. The Treaty of Paris, which ended the Crimea War, was to open the Danube to public law and European trade. This paper examines the circumstances in which entrepreneurs from the Rhône shipping industry, threatened in France by the rise of railways, attempted to reuse their ships by establishing a river shipping company operating between Moldavia and Serbia. The story of this ephemeral attempt, initially favoured by a navigation concession, is part of the debates initiated around the opening of the Danube to the navigation of all flags.