In 1921, the brigade was re-raised as a unit of Australia's part-time military forces, based in the state of Victoria.

At this time, the brigade's constituent units were located around regional New South Wales including Armidale, Inverell, Tamworth, Maitland, Newcastle and Adamstown.

[4] Following initial training at Broadmeadows in Victoria, they embarked for overseas in the second wave of Australian forces to be dispatched, leaving in December 1914.

[4] In April 1915, the brigade participated in the ANZAC landing at Gallipoli, arriving on the second day as the division's reserve,[5] before joining the eight-month campaign that followed.

[8] In June 1916, after spending a couple of months manning defences along the Suez Canal, the brigade, along with the rest of the 4th Division was transferred to Europe where they joined the war on the Western Front in France and Belgium.

The tactics used during the battle on 4 July 1918 were conceived by General John Monash and largely carried out by Australian infantrymen, along with a number of US troops.

[12] On 12 August 1918 Monash was knighted in the field by King George V.[5] The 4th Brigade remained in the front line until late September 1918,[4] taking part in the Hundred Days Offensive, including the fighting on 8 August, which was later described as the "Black Day" by the German commander, Erich Ludendorff.

These were: Albert Jacka, Martin O'Meara, John Dwyer, Harry Murray, Henry Dalziel, Thomas Axford, Maurice Buckley and Dominic McCarthy.

[18] In 1921, Australia's part-time military forces were re-organised to perpetuate the numerical designations and structure of the AIF formations that had existed during World War I.

[20] Where possible the decision was made to raise the new formations in the recruiting areas from where the World War I units had drawn their personnel.

[20] Initially, despite a level of war-weariness in Australia, numbers within the Citizens Force were maintained through voluntary recruitment and the compulsory training scheme, and due to strategic concerns around the expansion of Japanese naval power within the Pacific, there was a need to maintain a strong part-time military force.

[22] The manpower situation grew more acute in 1929 when the Scullin Labor government suspended the compulsory training scheme and replaced it with a voluntary "Militia".

[27] The manpower situation, however, began to improve in 1936 and then again in 1938 when tensions in Europe increased concerns about the possibility of another war.

[29] At the outbreak of World War II, the brigade was a part-time formation of the Militia, based in Victoria.

[33] In September 1944, the brigade returned to Australia for reorganisation and training before taking part in the New Britain campaign.

Post war, the brigade assisted with occupation duties and oversaw the Japanese surrender around Rabaul.

[43] Throughout the Cold War period which followed, the composition of the brigade changed a number of times as the role of part-time military forces evolved.

[44] During this time, due to increased manpower and resources, the brigade was able to achieve full manning and equipment scales and, as a result, in 1959, formed the basis of a 3,500-man combined arms exercise undertaken at Puckapunyal.

[49] In late 1964, however, the decision was made to end the experiment with the Pentropic establishment,[50] partly because of the difficulties it created with allied interoperability.

[51][52] By 1976, due to limited resources and manpower the brigade's parent formation, the 3rd Division, had become a largely hollow structure.