The Marne (/mɑːrn/; French pronunciation: [maʁn] ⓘ) is a river in France, an eastern tributary of the Seine in the area east and southeast of Paris.

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.

In the First Battle of the Marne (September 1914), the military governor of Paris, General Joseph Gallieni, took the initiative in driving the Germans back from the capital, rendering their war-plan inoperative.

[5] In the Second Battle of the Marne (July-August 1918), the last major German offensive on the Western Front was defeated by an Allied counter-attack, leading eventually to the Armistice.

[7] Furthermore, a portion of the Canal de l'Ourcq also runs parallel and quite close to the Marne before swinging away to enter Paris from the north; at one time the two were linked by a "tub-boat" inclined plane near Meaux.