During World War I, the 12th Brigade was re-raised in early 1916 as part of the expansion of the all volunteer First Australian Imperial Force. The brigade was formed in Egypt from a cadre of experienced personnel who had served during the Gallipoli Campaign as part of the 4th Brigade. Attached to the 4th Division and consisting of four infantry battalions—the 45th, 46th, 47th and 48th Battalions—it served in the trenches of the Western Front from June 1916 onwards. During this time, the brigade fought in several significant battles including the Battle of Pozières, the First Battle of Bullecourt, the Battle of Messines, the Battle of Passchendaele, and the German spring offensive. During the German spring offensive, the brigade fought a defensive action around Dernancourt. In May 1918, the brigade was one of three that was selected to disband one of its battalions in order to provide reinforcements to other units in the Australian Corps and it was at this time that the 47th Battalion was disbanded. The 12th Brigade's remaining battalions continued to fight after this, taking part in the final Allied offensive of the war, the Hundred Days Offensive, which was launched around Amiens in August and followed by a series of advances as the Allies broke through the Hindenburg Line.