The 25th Brigade was a brigade-sized infantry unit of the Australian Army that served during the Second World War. Raised in July 1940 and consisting of three infantry battalions, the 25th Brigade initially served in the United Kingdom, where it formed part of the garrison tasked with defending against a possible German invasion. In 1941, the brigade was redeployed to the Middle East where it took part in the Syria–Lebanon campaign fighting several actions around Merdjayoun and Jezzine.

The Battle of Balikpapan was the concluding stage of Operation Oboe, the campaign to liberate Japanese-held British and Dutch Borneo. The landings took place on 1 July 1945. The Australian 7th Division, composed of the 18th, 21st and 25th Infantry Brigades, with a small number of Netherlands East Indies KNIL troops, made an amphibious landing, codenamed Operation Oboe Two, a few miles north of Balikpapan. The Allied invasion fleet consisted of around 100 ships. The landing had been preceded by heavy bombing and shelling by Australian and US air and naval forces. The Allied force totalled 33,000 personnel and was commanded by Major General Edward Milford, while the Japanese force, commanded by Rear Admiral Michiaki Kamada, numbered between 8,400 and 10,000, of which between 3,100 and 3,900 were combatants. After the initial landing, the Allies secured the town and its port, and then advanced along the coast and into the hinterland, capturing the two Japanese airfields. Major combat operations concluded around 21 July, but were followed by mopping-up operations, which lasted until the end of the war in mid-August. Australian troops remained in the area until early 1946.