The Hindenburg Line was built between 2 and behind the German front line. On 25 February German forces began retreating to the line and the withdrawal was completed on 5 April, leaving behind a devastated territory to be occupied by the Allies. This withdrawal negated the French strategy of attacking both flanks of the Noyon salient, as it no longer existed. However, offensive advances by the British continued as the High Command claimed, with some justice, that this withdrawal resulted from the casualties the Germans received during the Battles of the Somme and Verdun, despite the Allies suffering greater losses.