What battle took place during an offensive that pushed the Germans out of France, forcing them to retreat beyond the Hindenburg Line?
Battle of the Scarpe (1918): The Battle of the Scarpe was a World War I battle that took place during the Hundred Days Offensive between 26 and 30 August 1918. Hundred Days Offensive: The Hundred Days Offensive was the final period of the First World War, during which the Allies launched a series of offensives against the Central Powers on the Western Front from 8 August to 11 November 1918, beginning with the Battle of Amiens. Hundred Days Offensive:  The offensive essentially pushed the Germans out of France, forcing them to retreat beyond the Hindenburg Line, and was followed by an armistice.
Battle of the Scarpe