31st / 51st Battalion ( Australia ) The 31st / 51st Battalion was an infantry battalion of the Australian Army , which served during World War II . Raised for service as part of the Militia in 1943 through the amalgamation of two previously existing battalions , the 31st / 51st Battalion undertook garrison duties in Dutch New Guinea in 1943 – 44 before taking part in the Bougainville Campaign in 1944 – 45 . Following the end of the war , the battalion served in the Pacific overseeing the transfer of Japanese prisoners of war and re - establishing law and order until mid - 1946 when it returned to Australia and was disbanded . History . Formation . The 31st / 51st Battalion was formed on 12 April 1943 at Yatlee , near Cairns , Queensland , by the amalgamation of two previously existing Queensland - based Militia infantry battalions : the 31st and 51st Battalions . Upon establishment , the battalion adopted the territorial title of the " Kennedy / Far North Queensland Regiment " , in order to perpetuate the designations of its two predecessor units . Although the battalion officially adopted the brown and yellow rectangular Unit Colour Patch of the 31st Battalion , members of the new battalion that had previously served with the 51st were authorised to wear its brown over light blue circular colour patch . Reinforcements to the unit were allocated the colour patch based upon the territorial area from which they had been recruited . The amalgamation came about due to a shortage of manpower in the Australian economy which had occurred as a result of an over mobilisation of Australia ' s military forces in the early years of the war . In an attempt to rectify this situation , the Australian government made the decision to release Militia personnel who had previously been employed in " essential industries " back into the civilian workforce . As a result of this , both the 31st and 51st Battalions , which had large numbers of personnel drawn from the agricultural sector , were well below their authorised establishments , and so it was decided that they would be merged to form a complete battalion . Merauke . Assigned to the 11th Brigade , 3rd Division , in May the newly formed battalion undertook amphibious training and intensive physical activities such as route marches around Yorkeys Knob , Queensland , in preparation for deployment overseas . In June – July 1943 , under the command of Lieutenant Colonel Geoffrey Brock , the battalion was deployed to Merauke , in Dutch New Guinea as part of Merauke Force . They departed from Cairns on board the TSS " Canberra " on 20 June , arriving at Thursday Island on 24 June . From there they were transferred to Horn Island before boarding the MV " Van de Ljin " and arriving at Merauke on 16 July 1943 . From July 1943 until August 1944 the battalion undertook long range patrols in the surrounding area and established outposts along the coast to the north - west . During this time the patrols from the 31st / 51st were involved in two major actions against the Japanese . The first came on 22 December 1943 near Japero , when a small patrol of nine men on board the " Rosemary " , a small diesel trawler , surprised a Japanese patrol consisting of two barges . In the fighting that followed , between 20 to 30 Japanese were killed for the loss of one Australian killed and five wounded . The second action came on 30 January 1944 when a waterborne force of about 200 Japanese was contacted and engaged by a 14 - man detachment at an outpost near the start of the Eilanden River , about from Merauke . Anchoring about from the outpost , the Japanese were engaged with fire from Bren light machine - guns , small arms and anti - tank rifles . Initially taken by surprise , the Japanese lost about men 60 killed before withdrawing about out to sea and engaging the outpost with heavy machine - guns and mortars . Nevertheless only three Australians were slightly injured as a result of the contact , receiving burns to their hands from their overheated Bren guns . On 24 July 1944 , the battalion was gazetted as an Australian Imperial Force unit , meaning that it could be sent outside of the bounds imposed upon Militia units as set out in the " Defence Act ( 1903 ) " . Shortly afterwards , they received orders that they would be withdrawn back to Australia in preparation for employment in combat elsewhere in the Pacific theatre . In early August 1944 , Lieutenant Colonel Philip Parbury took over command of the battalion , relieving Major Bernard Callinan who had been acting in the role after Brock was taken ill and later died in December 1943 . On 8 August the battalion embarked to return to Australia . Upon arrival , the men were given a brief period of leave before the battalion concentrated at Strathpine , Queensland , where they received reinforcements and undertook further training . They remained there for four months before departing for Bougainville on 6 December 1944 , under the command of Lieutenant Colonel Joseph Kelly . Bougainville . The 31st / 51st Battalion arrived at Torokina on Bougainville four days later and , along with the rest of the 11th Brigade , they began an offensive campaign which saw them involved in heavy combat with the Japanese . They were committed to the fighting in three periods . The first , between December 1944 and February 1945 , saw the battalion take Tsimba Ridge , cross the Genga River and capture Downs Ridge . Later , in March and April 1945 , they undertook long range patrols in the central sector of the island in the vicinity of the Numa Numa Trail . Their final commitment came between May and July 1945 when the battalion was switched to the northern sector , where they took part in the fighting around the Bonis Peninsula . As a part of this phase , the battalion fought along the Ratsua front and undertook a disastrous amphibious landing at Porton Plantation . Conceived as a company - level effort to outflank the significant Japanese defences that were holding up the advance from Ratsua , the operation was plagued by poor planning , inadequate resources , intelligence failures and strategic and tactical errors at all levels . After landing at the wrong beach on 8 June , and finding themselves caught in a tight box of Japanese defensive positions , the 190 men from ' A ' and ' C ' Companies , under Captain Henry Downs , were unable to advance inland . One of the landing craft ran aground and supplies began to dwindle . In an effort to link up with the beleaguered company , ' D ' Company , which was holding the line along the Ratsua front , attempted to breakthrough the Japanese lines . Although some patrols were able to penetrate to within of Porton , they were unable to get any closer . Eventually the order to withdraw was given from 11th Brigade headquarters . During the subsequent evacuation , two more landing craft ran aground and although one managed to float free , the other remained stuck hard on a reef . Over the course of the next couple of days , the men in the landing craft were subjected to heavy Japanese attack and it was not until 11 June that rescue efforts were completed . The battalion lost 23 men killed or missing , presumed dead , while a further 106 were wounded in the operation . Following the failure of the landing at Porton Plantation , the planned Australian advance into the Bonis Peninsula was called off , and the Australians focused their main effort on Bougainville towards the capture of Buin in the south . The effort in the north was reduced to that of a holding action as further resources were transferred out of the sector . Nevertheless , the 31st / 51st Battalion continued to undertake patrols along the Ratsua front , during which they suffered further casualties , until they were withdrawn from combat operations on 28 June . They were subsequently moved back to Torokina . Disbandment . Following the cessation of hostilities on 15 August 1945 , the battalion undertook garrison duties on Nauru and Ocean Island . In this role they helped to maintain law and order and investigate war crimes , oversaw the transfer of over 4 , 000 Japanese prisoners of war to Bougainville and maintained a military administration until 1 November 1945 when civil control was re - established . A short time later , the detachment on Ocean Island was withdrawn back to Nauru . In December 1945 , most of the battalion ( except one platoon ) was withdrawn to New Britain to rejoin the 11th Brigade . In February 1946 , the platoon that had remained on Nauru arrived in Rabaul . As the demobilisation process began , the 31st / 51st stayed on New Britain until May when they received orders to return to Australia . On 15 April Lieutenant Colonel Donald Lamb took over as battalion commander . As personnel were discharged or transferred to other units for further service , the battalion ' s numbers declined until eventually , on 4 July 1946 , the battalion was disbanded . Throughout the course of the war , the 31st / 51st Battalion lost 61 men killed and 168 wounded . The majority of these came during the fighting on Bougainville where 41 men were killed in action , seven were posted as missing in action ( presumed killed ) and 12 died of wounds . Members of the battalion received the following decorations : one Distinguished Service Order , one Distinguished Conduct Medal , three Military Cross es , 10 Military Medal s , one British Empire Medal and 27 Mentions in Despatches . Both the 31st and 51st Battalions were later re - raised as separate units when Australia ' s part - time military was re - raised in 1948 under the guise of the Citizen Military Forces . Later , they became company - level formations of the Pentropic 2nd Battalion , Royal Queensland Regiment , in 1960 . A further re - organisation saw the units split again in 1965 and re - raised as battalion - level formations under their old numerical designations . They have remained separate since then . Battle honours . For their involvement in World War II , the 31st / 51st Battalion received the following battle honour s : Commanding officers . The following officers served as commanding officer of the 31st / 51st Battalion :