Battle of Ratsua The Battle of Ratsua occurred during the Second World War and involved Australian and Japan ese forces . Part of the wider Bougainville Campaign of the Pacific theatre , the battle took place in the northern sector of Bougainville between June and August 1945 . Following the failed landing at Porton Plantation in early June , the fighting around Ratsua essentially became a containment action for the Australians as they concentrated their efforts upon driving south towards Buin , which was the main centre of Japanese resistance on the island at the time . As a result , the situation around Ratsua remained largely static until the end of hostilities in mid August . Background . After their defeat at Tsimba Ridge in early February 1945 , Major General Kesao Kijima — commander of the Japanese 38th Independent Mixed Brigade — had ordered a withdrawal to Numa Numa , leaving a force of 1 , 400 sailors drawn from the 87th Naval Garrison Force and 2 , 000 civilians to hold the Bonis Peninsula . Of these civilians , about 600 were armed , although only half were trained to undertake a combat role . As their supplies dwindled , in May – June the Japanese sailors — under the command of Captain Kato , the senior naval officer in Buka — began to raid the Australian supply lines between Ruri Bay and Ratsua as they attempted to hold a position between Porton Plantation and Tarbut . Meanwhile , Australian troops from the 11th Brigade had continued their advance north from Tsimba Ridge in April – May , clearing up to the Soraken Peninsula which was captured by the middle of the month . By the end of May , however , the Japanese fell back behind a series of fortified positions along the base of the Bonis Peninsula , and the Australian advance came to a halt . In an effort to break this resistance and allow the northwards advance to continue , the Australians attempted to outflank the Japanese line of resistance by launching an amphibious landing at Porton Plantation on 8 June . The plan called for a reinforced company from the 31st / 51st Battalion to land behind the Japanese positions and attack from the west , while the main force consisting of the remainder of the 31st / 51st Battalion and the 26th Battalion attempted to break through from the south . Due to poor planning , inadequate resources and strong Japanese defence , however , the landing failed at considerable cost to Australians , and as their efforts turned towards effecting a withdrawal from the beachhead and rescuing the stranded men , the attempt by the main force to break through from Ratsua also failed as tired troops came up against strong Japanese defensive positions . Battle . Following the failed landing by the Australians at Porton Plantation , the commander of the Australian II Corps , Lieutenant General Stanley Savige , decided to focus the main effort of the Australian campaign upon driving south towards the Japanese garrison at Buin , where the bulk of the Japanese forces were holding out . In order to concentrate enough forces for the next phase of the operation , however , Savige decided that the 11th Brigade , which had been carrying the advance north , should be relieved so that it could be transferred to the south following a period of rest and reorganisation . Nevertheless , there was still a need to maintain the pressure upon the Japanese in the north , and so the 23rd Brigade — which had been previously operating in the central sector after being transferred from garrison duty in the Outer Islands — was also given responsibility for the northern sector as well , relieving the 11th Brigade on 20 June . The brigade ' s commander — Brigadier Arnold Potts — was charged with keeping the Japanese force bottled up on the Bonis Peninsula and to send out patrols towards the Buka Passage . Initially , Potts was only allowed to allocate one of his three battalion s — the 27th — for the task , as the other two — the 7th and 8th Battalions — were to remain in the central sector ; however , after intelligence reports indicated that the Japanese forces in the northern sector were stronger than the Australians initially thought , he requested permission to transfer the 8th Battalion , along with a battery of artillery from the 4th Field Regiment that was to be based on the Soraken Peninsula . Due to the requirements of the advance to the south , however , no engineer or armoured support was initially available . This request was approved , and by 28 June the two battalions and their supporting artillery were assembled ; the 8th on the left , or western side of the peninsula , and the 27th on the right , with the artillery based on the Soraken Peninsula . The two battalions sent fighting patrols forward , however , due to the dense terrain , the Australian line of communication was quite long and the infantry spread out over a very wide area — with each battalion occupying a front , which was twice the normal standard — security of their rear areas became an issue as the Japanese took the opportunity to disrupt the Australian logistic efforts , conducting ambushes , cutting communications and planting mines along the tracks . As the ambushes increased and casualties mounted , forward movement came to a halt , and by 21 July , the 27th Battalion reported having lost 10 men killed and 36 wounded without having gained any ground . In light of this failure , the Australian brigade commander requested further resources to undertake a full scale offensive aimed at clearing the Japanese from the peninsula . This request was passed up to corps - level , however , there it was denied as Savige could not afford to release assets that were being used in the drive south . Under pressure to keep casualties to a minimum due to criticism in the media in Australia , Potts formulated a plan to withdraw the 27th Battalion from the right flank and to instead concentrate his forces on the left flank along a front around the plantation at Buoi , to the north of Ratsua . Savige agreed to this on 22 July and the following day the 8th Battalion launched an attack against a feature known to them as " Commo Ridge " , where it was believed that the Japanese were attempting to set up a forward position . The attack went in after a preliminary attack from the air , with one company attacking with two Matilda tanks from the 2 / 4th Armoured Regiment in support . Although the airstrike had been largely ineffective and both of the tanks struggled to cross the " swampy ground " , the direct fire support provided by the tanks proved decisive and the Australians took the position within 20 minutes , killing 12 Japanese . On 24 July , the 8th Battalion launched another attack with two platoon s assaulting the Japanese position known as " Base 5 " . Prior to the assault , over 900 artillery shells and mortar bombs were brought down on the Japanese positions in an effort to prepare the position for the attack , however , this proved ineffective against well entrenched positions . The Australians reached their first objective , which was a small ridge in front of the main Japanese position , however , shortly after they began receiving effective fire from concealed positions which killed two men and wounded another in the forward section , pinning it in place . Attempts to outflank the bunkers were answered with heavy fire from a medium machine gun and another man was killed and three more wounded . As the attack began to falter , one of the wounded , a 20 - year - old private , Frank Partridge , who had been injured in the arm and thigh , braved the heavy fire that was being put down towards him and gathered the Bren light machine gun from the man who had been killed . After pouring suppressing fire onto the bunker , he discarded the Bren and regathered his rifle , before rushing towards the bunker with a grenade and killing its occupants . Partridge ' s actions reinvigorated the attack and allowed the Australians to take the second Japanese position . After the wounded were recovered , however , they withdrew having lost three men killed and five wounded . Against this eight Japanese were confirmed to have been killed . For his actions during the attack on 24 July , Partridge was awarded the Victoria Cross , the British Commonwealth ' s highest military decoration . He was the last Australian to be awarded the medal during the Second World War , and was also the youngest . Elsewhere , the Australians continued to mount patrols . On 2 August , a patrol from the 27th Battalion was sent out along the Ruri Bay Road in company with two tanks that were to act as their direct fire support . The Japanese were still active in the area , however , and had mined the road with a bomb which they had rigged to be detonated remotely . The Australian patrol triggered the device and the resulting explosion killed three men in one of the tanks and wounded eight infantrymen following behind . On 5 August , the Australians reoccupied the position at Base 5 after encountering only slight resistance and subsequently named it " Part Ridge " . After exploiting the position , it was discovered that the Japanese had built over 60 bunkers in the area , and subsequently they were withdrawn from the ridge again . Aftermath . On 11 August , in anticipation of the capitulation of Japan following the dropping of two atomic bombs on Japanese cities , the order to cease offensive combat operations on Bougainville was passed to all Australian units . Three days later , on 15 August , the Japanese Emperor Hirohito publicly announced Japan ' s unconditional surrender , effectively bringing about an end to the war . On 18 August , in the southern sector of the island the Japanese commander , General Masatane Kanda , dispatched an envoy across the swollen Mivo River to begin negotiations with the Australians for the surrender of the over 23 , 000 Japanese soldiers left on the island , bringing about an end to the campaign . Throughout the course of the fighting on Bougainville from November 1944 to August 1945 , 526 Australians were killed , while a further 1 , 572 were wounded . It is believed that 8 , 500 Japanese were killed in action , while a further 9 , 800 had died from disease during this same period .