The 20th Brigade was a brigade-sized infantry unit of the Australian Army. First raised in 1912 as a Militia formation to provide training under the compulsory training scheme, the brigade was later re-raised on 7 May 1940 as part of the all volunteer Second Australian Imperial Force for service during the World War II. The brigade was initially assigned to the 7th Division, but was later transferred to the 9th Division in early 1941. They subsequently took part in the Siege of Tobruk that year, and then the First and Second Battles of El Alamein in 1942. In early 1943, the brigade was returned to Australia to join the fighting against the Japanese in the Pacific. In late 1943, the brigade took part in the capture of Lae and then the Huon Peninsula campaign. Withdrawn to Australia in early 1944, its final campaign came during the Battle of North Borneo in the final months of the war. It was disbanded in February 1946.