The 20th Battalion was raised in March 1915 in Liverpool, New South Wales, as part of the Australian Imperial Force (AIF). A small number of its original recruits had already served with the Australian Naval and Military Expeditionary Force in New Guinea in 1914. After undertaking initial training, the battalion left Australia in June and after a further period of training in Egypt they landed at Anzac Cove on 22 August 1915 as part of the 5th Brigade, 2nd Division. They played only a minor part in the fighting during the August Offensive which was coming to a close by the time they arrived and so for the majority of time that they were at Gallipoli, the battalion was deployed in the defence of Russell's Top. They remained on the peninsula until the evacuation on 20 December 1915.