The 3rd Battalion was an infantry battalion of the Australian Army. Originally raised as part of the First Australian Imperial Force for service during World War I, the battalion formed part of the 1st Brigade, attached to the 1st Division. It was formed shortly after the war broke out and was among the first Australian units to be sent overseas, arriving in Egypt in December 1914. In April 1915 the battalion participated in the Landing at Anzac Cove, coming ashore in the second and third waves. In December 1915 the 3rd Battalion was evacuated from the Gallipoli peninsula and withdrawn to Egypt again, where it took part in the defence of the Suez Canal before being sent to France to fight on the Western Front in March 1916. For the next two and a half years the unit would serve in the trenches in France and Belgium and would take part in many of the major battles fought during that time. In May 1919, following the end of the war, the battalion was disbanded and its personnel repatriated back to Australia.

1st Brigade is a combined arms formation of the Australian Army. Formed in 1903 as a militia formation based in New South Wales, it was reconstituted as part of the Australian Imperial Force in 1914 for service during World War I, the brigade fought at Gallipoli and on the Western Front before being disbanded in mid-1919. In 1921, the 1st Brigade was re-raised as a unit of Australia's part-time military forces, based in New South Wales. During World War II the brigade undertook defensive duties before being disbanded. In 1948, it was re-raised as an integral part of the Australian Regular Army. Currently the brigade is based at Robertson Barracks in Darwin and at RAAF Base Edinburgh near Adelaide, South Australia. It is the first of the Australian Army brigades to be re-organised as a combat brigade under Plan Beersheba.