2 / 4th Pioneer Battalion ( Australia ) The 2 / 4th Pioneer Battalion was a unit of the Australian Army raised for service during the Second World War . An pioneer unit , the battalion undertook both infantry and engineer tasks . Despite being raised early in the war , the battalion did not see action until the final months , taking part in the Borneo campaign where , as part of the 1st Beach Group , it fought against the Japanese in support of the 9th Division . It was disbanded in early 1946 following the end of hostilities . History . Formed in February 1941 at Greta , New South Wales , the 2 / 4th Pioneer Battalion was one of four pioneer battalion s raised to provide engineer support to the 2nd Australian Imperial Force ’ s four infantry division s . Trained as infantry , the battalion undertook both the infantry and engineer support roles and was organised along conventional infantry lines with a headquarters and four companies , but was made up of personnel with trade or practical skills , and within the divisional structure , the pioneers were administered as corps troops under the direction of the divisional engineer commander . Allocated to the 23rd Brigade of the 8th Division , after initial training it was sent north to Darwin in September to construct defences around the Adelaide River and Noonamah amidst concerns about Japanese intentions in the Pacific . While most of the division deployed to Malaya , the 2 / 4th remained behind and following the Japanese entry into the war , the battalion was allocated to bolster the garrison at Koepang as part of Sparrow Force on Timor . An advanced party was sent to the island in early February 1942 , and on 14 February the rest of the battalion followed ; however , the convoy in which they were embarked was attacked by Japanese aircraft and it was turned back . Returning to Darwin , the majority of the 2 / 4th ’ s equipment was lost when the ship carrying it was sunk in Darwin harbour during a Japanese air attack on 19 February . Consequently , the battalion ’ s deployment was cancelled and it remained in the north for more than a year , during which time they undertook defensive duties to counter the threat of Japanese invasion . During this time , the battalion was commanded by Lieutenant Colonel John McCarty . In November 1942 , the battalion was re - assigned to the 3rd Brigade , a Militia formation that had been mobilised for full - time service and sent to the Northern Territory earlier in the year to bolster the field force there . In March 1943 , the strategic situation had improved and the pioneers were relieved of garrison duties , moving to the Atherton Tablelands where the 2nd AIF divisions were converted to the jungle division establishment as the Army prepared to go on the offensive in New Guinea . The battalion remained there throughout 1943 and the following year it was assigned to the 1st Beach Group , which had been raised to provide support to amphibious operations . In mid - 1945 , the battalion finally went into action . In June that year , as part of one of the final Australian operations of the war , the battalion landed on Labuan as part of the Operation Oboe landings in Borneo , assigned to support the 9th Division . Serving in the terminal support role around the beachhead , the 2 / 4th saw limited combat and its casualties during the fighting on Borneo were light with only five men being killed in battle . The majority of these were suffered during a raid on the Australian beachhead by 50 Japanese soldiers on 21 June . Following the conclusion of hostilities in August 1945 , the battalion remained in the Kuching area where it undertook garrison duties maintaining law and order and processing Japanese prisoners of war for return to Japan , before returning to Australia in December . As the demobilisation process began , the battalion ’ s personnel were transferred for further service or discharged and it was eventually disbanded in early 1946 . For its service during the war , the 2 / 4th received two battle honour s : South - West Pacific 1945 and Borneo . Nineteen men were killed in action or died on active service while serving with the battalion and three were wounded ; two members of the battalion were decorated with a Mention in Despatches . After the war , the pioneer role was assumed as a specialisation within the conventional infantry establishment within the Australian Army , and consequently the wartime pioneer battalions have not been re - raised .