Originally raised in 1915 for service during World War I as part of the 1st Australian Imperial Force, it was attached to the 6th Brigade, 2nd Division and served during the Gallipoli campaign and in the trenches of the Western Front in France and Belgium.

[3] Organised into four rifle companies, designated 'A' through to 'D', with a machine gun section in support, the battalion had an authorised strength of 1,023 men of all ranks.

[1][4] After arriving in Egypt, the 24th completed its training during July and August before being sent to Gallipoli in early September as reinforcements for the forces that had landed there in April.

It was during this final attack, on 5 October, that one of the battalion's subalterns, George Ingram, performed the deeds that resulted in him being awarded the Victoria Cross.

[10] To a large extent most of these units were raised in the areas from where their personnel had been drawn during the war, thus maintaining their regional links in the process.

[12] At the outset of the World War II, due to the provisions of the Defence Act (1903) which prohibited sending the Militia to fight outside of Australian territory,[14][Note 2] the decision was made to raise an all volunteer force to serve overseas—initial operations were conceived to be likely in the Middle East, France and later possibly the United Kingdom—while it was decided that the Militia would be used to defend the Australian mainland and to improve Australia's overall level of readiness through the reinstitution of compulsory military service and extended periods of continuous periods of training.

[16] During this time the 24th/39th Battalion undertook a number of periods of continuous training, firstly in September 1939 when a company-sized element exercised at Trawool for a month.

Following Japan's entry into the war, the 39th Battalion was sent to New Guinea and would go on to play a key role in the Australian defensive actions along the Kokoda Track in July and August 1942.

In 1943, the battalion was deployed to New Guinea aboard the transport Duntroon[19] along with the rest of the 3rd Division, arriving in Port Moresby over the course of three months between February and April.

[22] Later, in September 1943, the battalion attacked Markham Point,[23] before being detached to the 7th Division for the Finisterre Range campaign, during which they moved from Nadzab to Dumpu and helped to clear the Ramu Valley in early 1944, securing the 15th Brigade's western flank as the Australians pushed the advance towards Madang, which was secured in April 1944 by the 57th/60th Battalion.

[12][24] In August 1944, the 24th Battalion was withdrawn back to Australia, embarking aboard the transport Van Heutsz at Madang, for rest and reorganization.

[25] After the soldiers returned from leave, a period of re-organisation and training followed on the Atherton Tablelands before the 24th Battalion deployed with the rest of the 15th Brigade to Bougainville in April 1945.

In mid-June, after bypassing Unani along a lateral track that passed behind Monoitu, the battalion was involved in actions around the Hari and the Ogorata Rivers,[27] pushing towards Kingori and then on to Katsuwa along the Commando Road, crossing the Mobiai.