In October 1941, during World War II, the two battalions were delinked and the 53rd was later deployed to New Guinea, where they took part in the Kokoda Track campaign.

Poorly prepared and trained, and lacking up to date equipment, they did not perform well and were amalgamated with the 55th once more in October 1942, with whom they took part in further campaigns in New Guinea and Bougainville, before being disbanded in May 1946.

The 53rd Battalion was initially raised in mid-February 1916 as part of the expansion of the all-volunteer First Australian Imperial Force (1st AIF) that took place in Egypt during World War I.

Once that was over, the battalion rotated between manning defensive positions at the front and undertaking training and labouring duties in the rear areas.

[7] As the Allies were pushed back by the offensive, the Australian divisions were brought south to the Somme to help blunt the German advance.

[9] Due to the impact of the Great Depression, and a general complacency towards matters relating to defence, the battalion had few volunteers and limited funding.

It was decided that the Militia would be used to defend the Australian mainland and to improve Australia's overall level of readiness in the event of war in the Pacific, through the reinstitution of compulsory military service and extended periods of training.

[15] In October 1941, the 55th/53rd Battalion was undertaking a period of continuous training at Bathurst, New South Wales, when it was announced that they were to be delinked once more and the 53rd would be sent to act as a garrison force in Darwin, Northern Territory.

In December, as they were due to embark for the trip to the north, they were still below strength and in order to meet this shortfall they received a draft of 104 conscripts.

Japan had entered the war the previous month and the battalion was to form part of the garrison for the port, in case of a possible invasion.

[11][17] Suffering badly from malaria and other tropical diseases, the men were mainly used to provide work parties, instead of undertaking the training that they would require for the fighting that would come.

[11] The two detached companies moved into position and upon their arrival they received a number of Bren guns and had a small amount of training with them, but it was not enough to bring them up to the standard required for combat against the battle-hardened Japanese soldiers that they were about to come up against.

[11] As a result of this loss, communications between the companies broke down, rendering co-ordinated action impossible and 53rd began to fall back.

This came at the worst possible moment for the Australians, as it left a gap in their defences along the Kokoda Track, leaving the way open for the Japanese to march straight through to Alola.

[11] Holding their position as required, the 53rd Battalion remained in the line until the night of 5 September, when they were ordered to fall back along the track.

They were eventually removed from the front line fighting, being utilised instead in mundane garrison duties in the rear areas, while 100 men were transferred to reinforce the 39th Battalion.