During World War I, the 17th Brigade was formed as part of the all volunteer First Australian Imperial Force (AIF) in England, on the Salisbury Plain, as part of the 6th Division on 25 April 1917. The brigade consisted of four infantry battalions, and supported by a machine gun company and a light trench mortar battery. By September 1917, the brigade's strength was just over 3,000 men. Heavy casualties amongst Australian forces on the Western Front at Bullecourt and Messines throughout 1917 resulted in a manpower shortage amongst the five divisions of the AIF. As a result, plans to raise the 6th Division were shelved and its constituent formations were disbanded without seeing any action. The brigade's personnel were then used as reinforcements. The brigade's machine gun company was later re-designated as the 24th Machine Gun Company and eventually allocated to the 4th Machine Gun Battalion, going to serve as part of the 4th Division. Only 15 infantry brigades were raised as part of the Militia during the interwar years, so the 17th Brigade was not re-raised during this time.