Following the outbreak of the Second World War the battalion held a number of training exercises and camps until 1941, before being mobilised in March 1942 as part of the 29th Brigade, in the 5th Division.

Today, its lineage is perpetuated by the 31st/42nd Battalion, Royal Queensland Regiment, a unit which continues to serve in the Australian Army Reserve.

The 42nd Battalion was raised at Enoggera near Brisbane, Queensland, in December 1915 as part of the Australian Imperial Force (AIF) during the First World War.

[2] After this, the Australian Corps was withdrawn from the line for rest and reorganisation,[4] and the 42nd Battalion was disbanded on 22 October 1918 to provide reinforcements for other AIF units, which had suffered heavy casualties throughout the year.

[1] With its men mainly recruited from Sarina, Carmilla, and Yeppoon in Central Queensland, it had training centres in Rockhampton, Mount Morgan, and briefly also in Gladstone and Mackay.

In March 1942, as the threat posed by the Japanese in the Pacific grew, the battalion was mobilised for full-time service and moved to Tiaro.

In early 1942, the 29th Brigade moved to Townsville and was tasked with preparing defensive positions between Giru and Rollingstone in case of a Japanese invasion.

In August, the battalion returned to Australia after 18 months on operations, encamping at Young's Crossing in Petrie, Queensland, for reorganisation after a period of leave.

Entering the abandoned village of Mawaraka on 17 January, the battalion occupied it and then began patrolling forward, frequently clashing with Japanese forces amid the swamps in the area.

Meeting strong resistance the brigade advance was held up; however, the Japanese were subsequently cleared and the Silibai River captured on 10 July.

[8] In 1948, the 42nd Infantry Battalion, The Capricornia Regiment was reformed as part of the re-raised Citizens Military Forces (CMF), with three companies in Rockhampton and its headquarters in Maryborough.