The German offensive ground to a halt in mid @-@ July and a brief lull followed , during which the Australians undertook a series of raids , known as Peaceful Penetrations . The Allies soon launched their own offensive — the Hundred Days Offensive — ultimately ending the war . Beginning on 8 August 1918 the offensive included four Australian divisions striking at Amiens . Using the combined arms techniques developed earlier at Hamel , significant gains were made on what became known as the " Black Day " of the German Army . The offensive continued for four months , and during Second Battle of the Somme the Australian Corps fought actions at Lihons , Etinehem , Proyart , Chuignes , and Mont St Quentin , before their final engagement of the war on 5 October 1918 at Montbrehain . The AIF was subsequently out of the line when the armistice was declared on 11 November 1918 .