The Marne is a river in France, a tributary of the Seine in the area east and southeast of Paris. It is about 525 km (326 mi) long. The river gives its name to the Marne département; during World War I two battles were fought along it.

The Marne starts in the Langres plateau, runs generally north then bends west between Saint-Dizier and Châlons-en-Champagne, joining the Seine at Charenton just upstream from Paris.