The Battle of Amiens, which began on 8 August 1918, was the opening phase of the Allied offensive later known as the Hundred Days Offensive that ultimately led to the end of the First World War. Allied forces advanced over seven miles on the first day, one of the greatest advances of the war. The battle is also notable for its effects on both sides' morale and the large number of surrendering German forces. This led Erich Ludendorff to describe the first day of the battle as "the black day of the German Army." Amiens was one of the first major battles involving armoured warfare and marked the end of trench warfare on the Western Front; fighting becoming mobile once again until the armistice was signed on 11 November 1918.