Following Japan's entry into the war in December 1941, the battalion was mobilised for war service. In early 1942, when concerns about a Japanese invasion of Australia heightened, the battalion, consisting of 44 officers and 890 other ranks, was moved to Jimboomba, in Queensland, from Bonegilla. The invasion did not eventuate and the government decided to demobilise part of the military to rectify a manpower shortage that developed in the Australian economy. As a result, on 27 August 1942, the 52nd Battalion was once again amalgamated with the 37th Battalion to form the 37th/52nd Battalion, and some of its personnel were released back to civilian industry. The 10th Brigade was disbanded around this time, and subsequently the 37th/52nd Battalion was assigned to the 4th Brigade. Together the amalgamated battalion subsequently served in the Huon Peninsula and New Britain campaigns in 1944 and 1945 before being disbanded on 12 June 1946.