Marne, Battles of theWorld War I, two unsuccessful German offensives in northern France. In the First Battle 6-9 September 1914, German advance was halted by French and British troops under the overall command of the French general Jospeh Joffre; in the Second Battle 15 July-4 August 1918, the German advance was defeated by British, French, and US troops under the French general Henri Pétain, and German morale crumbled.