Throughout 1917 the 20th Battalion was involved in three major battles as the German Army was forced back towards the Hindenburg Line, seeing action at Bullecourt in May, Menin Road in September and Poelcappelle in October. At Lagnicourt, on 15 April, along with other units from the 5th Brigade, they took part in a defensive action along with four other battalions, where they managed to defeat a counter-attack by a German force almost five times its size. In 1918, the battalion was involved in repelling the German Spring Offensive, when the 20th was one of many Australian battalions that were hurried in to the line to stop it, and on 7 April 1918, they took part in a very sharp engagement at Hangard Wood. Once the German offensive was defeated, the Allies launched their own, known as the Hundred Days Offensive which eventually brought about an end to the war. During this time the 20th were involved in the battles at Amiens and Mont St Quentin in August, before participating in the attack on the "Beaurevoir Line" at Montbrehain in October.