The 2/31st Battalion was an infantry battalion of the Australian Army that served during World War II. It was raised in June 1940 and was assigned to the 25th Brigade, 7th Division. It initially served in the United Kingdom where it undertook defensive duties before being moved to the Middle East in 1941. After taking part in the fighting in Syria and Lebanon, the battalion undertook garrison duties around Tripoli before being transferred back to Australia in 1942. In late 1942 the battalion was sent to New Guinea to fight against the Japanese along the Kokoda Track. They subsequently fought a number of battles throughout 1942, 1943 and early 1944. Their last campaign came in mid-1945 when they landed on Borneo. After the war the battalion was disbanded in March 1946.

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.