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 and 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 Shortly afterwards, they received orders that they would be withdrawn back to Australia in preparation for employment in combat elsewhere in the Pacific theatre.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 where, along with the rest of the 11th Brigade, they formed part of