The 21st Brigade was a brigade-sized infantry unit of the Australian Army. It was briefly raised in 1912 as a Militia formation providing training as part of the compulsory training scheme. Later, it was re-formed in April 1940 as part of the Second Australian Imperial Force, the unit was raised for service during World War II. As part of the 7th Division the brigade's constituent units were raised from volunteers from several Australian states. After rudimentary training in Australia, the brigade deployed for the Middle East in October 1940. Defensive duties were mounted along the Libyan border in early 1941, before the brigade was committed to the Syria-Lebanon campaign, fighting against Vichy French forces. In early 1942, following Japan's entry into the war, the brigade returned to Australia. After a period of defensive duties in Australia, it was deployed to New Guinea and subsequently played a key role in the Kokoda Track campaign, delaying the Japanese advance towards Port Moresby and then joining the pursuit as the Japanese withdrew towards Buna–Gona. In 1943–1944, the brigade took part in the capture of Lae and the Ramu Valley–Finisterre Range campaign. Its final campaign of the war, came in the final months when it took part in the Balikpapan landings. It was disbanded in 1946. History Formation The 21st Brigade briefly existed as Militia brigade that was partially formed in 1912, following the introduction of the compulsory training scheme. At this time, it was assigned to the 5th Military District. The brigade's constituent units were spread across various locations in Western Australia including Kalgoorlie, Leonora, Boulder, Coolgardie, Albany, Wagin and Northam. The brigade consisted of only three infantry battalions, instead of the four that was usual at the time. These were consecutively designated as the 83rd, 84th and 85th Infantry Battalions. The formation was short lived, and was not raised as part of the First Australian Imperial Force (AIF) during the First World War. It remained on the order of battle as a Militia formation during the war, but was not re-raised in the interwar years when the Militia was reorganised to replicate the numerical designations of the AIF in 1921. The brigade was re-formed on 4 April 1940 as part of the 7th Division of the Second Australian Imperial Force (2nd AIF). Upon establishment, the brigade opened its headquarters in May 1940, in Melbourne, Victoria. Consisting of three infantry battalions—the 2/14th, 2/16th