The First Battle of the Marne was a battle in the First World War. It was fought between the German Empire on one side, and the French and British on the other. The battle ended with a tactical retreat of the German army. It was one of the first signs that the Schlieffen Plan had failed. The battle cost the lives of over one million French and British soldiers. It also cost the lives of over 750,000 soldiers on the German side. The battle was fought from 5 - 12 September 1914. The battle marked the end of the German advance into France. It marked the beginning of trench warfare that World War I became famous for.