Operation of Pacific War of World War II
The Landing at Jacquinot Bay was an Allied amphibious operation undertaken on 4 November 1944 during the New Britain Campaign of World War II. The landing was conducted as part of a change in responsibility for Allied operations on New Britain. The Australian 5th Division, under Major General Alan Ramsay, took over from the US 40th Infantry Division, which was needed for operations in the Philippines. The purpose of the operation was to establish a logistics base at Jacquinot Bay on the south coast of New Britain to support the 5th Division's planned operations near the major Japanese garrison at Rabaul.
Brigadier Raymond Sandover's 6th Brigade was directed to secure the Jacquinot Bay area. While the region was believed to be undefended, the initial landing was conducted by a combat-ready force comprising the reinforced Australian 14th/32nd Battalion protected by warships and with aircraft on standby. As expected, there was no opposition to the landing on 4 November and work soon began on logistics facilities.
Once a base was established at Jacquinot Bay, it was used to support Australian operations toward Rabaul. These were conducted in early 1945 in conjunction with advances on the northern side of New Britain. The campaign was effectively one of containment, isolating the larger Japanese force and allowing the Allies to conduct operations elsewhere.
Background.
Geography.
Jacquinot Bay lies on the south coast of the island of New Britain, to the east of Gasmata and the west of Wide Bay. The southern part of the island (i.e. excluding the Gazelle Peninsula and the isthmus) is dominated by a densely forested central mountain range. The range rises to and sits inland from a narrow coastal shelf. In 1943–1944, there were numerous small villages and localities around the bay. The main ones were Cutarp, a coconut plantation which lay on a headland to the north-east, and Palmalmal which lay to the south-west. In between, the village of Pomio lay on the northern shores of the bay. There was a coconut plantation around the southern part of the bay at Wunung, which was bounded by two freshwater rivers to the north and south, and another plantation around Palmalmal. A Roman Catholic mission was located at Mal Mal, although it was reportedly abandoned at the time. The beach opposite Pomio was considered suitable for landing operations, but between Pomio and Wunung, there was dense rainforest along the coast. Between Wunung and Palmalmal, the beach was considered suitable for landings, with some shelter offered to smaller vessels close in. There were only limited tracks around the region, and those that existed were assessed as not being suitable for motor traffic without improvement.
The region's climate was described as "hot and humid", with exceptionally high rainfall. The southern coastal region experienced a higher rainfall than the northern coast. The southern coast experienced a monsoon season during May to November, with the wettest period between July and September. Rain events were mainly at night or early morning. An Allied study completed in 1943 assessed average monthly rainfall at Palmalmal as in July, in August and in September. In the last quarter of the year, rainfall was assessed as declining, with November (the month of the operation) averaging around . Temperatures at the time were recorded at Gasmata as ranging between , although minimum temperatures largely averaged between and maximum temperatures averaged between . Humidity ranged between 75 and 85 percent. In terms of population, there were very few Europeans in the area prior to the war, with estimates ranging from 20 to 25. The indigenous population occupied several villages in the coastal area and the mountains, and were considered to form two main groups based around these areas.
The area around Jacquinot Bay was part of the Australian Territory of New Guinea, which had been mandated in 1920, and was considered to be under government control prior to the Japanese invasion. It formed part of the Gasmata sub-district, with a government and police post situated at Pomio, and was administered by an assistant district officer who reported to Rabaul. During the withdrawal of Allied forces from Rabaul in early 1942, the local population along the south coast had assisted Allied stragglers, and were believed to be supportive of the Allied cause, albeit pragmatic in their approach to the Japanese occupation.
Strategic situation.
During late 1943 and early 1944 Allied forces in the South West Pacific Area undertook Operation Cartwheel. This was a major offensive which aimed to isolate the main Japanese base in the area at Rabaul on the north-eastern tip of New Britain, and capture airstrips and anchorages which were needed to support a subsequent advance towards the Philippines. During December 1943 and January 1944 United States Army and United States Marine Corps units successfully landed in western New Britain at Arawe and Cape Gloucester. Japanese forces in western New Britain suffered a further defeat at Talasea in March 1944. Securing the western island prevented the Japanese launching attacks against the flank of the main Allied offensive along the north coast of New Guinea. Allied operations to secure the Huon Peninsula and the Markham–Ramu Valley, on the New Guinea mainland concluded in April 1944 with the capture of Madang. The focus of Allied operations on the mainland then turned towards securing Western New Guinea. The Admiralty Islands were captured during a campaign which lasted between 29 February and 18 May 1944. On Bougainville, a strong Japanese counter-attack had been repulsed in March 1944. A period of relative quiet followed until late 1944, after Australian forces relieved the US garrison (arriving from October).
The Japanese Eighth Area Army, under General Hitoshi Imamura, was headquartered at Rabaul. Its area of operations encompassed the Solomon Islands chain (including Bougainville), mainland New Guinea and the Bismarck Archipelago (of which, New Britain was the largest island). It had suffered significant reversals on mainland New Guinea and in the Solomon Islands. With the loss of western New Britain, Imperial Japanese Army (IJA) forces were concentrated in the north-east of the island on the Gazelle Peninsula to defend Rabaul against a direct attack. The Imperial Japanese Navy (IJN) maintained a network of coastwatching stations along New Britain's coast. The Japanese garrisons and some local officials used brutality to try and rule the civilian population. In March 1944 the Eighth Area Army was directed by the General Staff to "hold the area around Rabaul for as long as possible, in cooperation with the Imperial Japanese Navy". Until mid-1944 the Eighth Area Army believed that the Allies would conduct a major assault on Rabaul. After this time, they judged that the Allies were more likely to gradually expand their control over New Britain and only attack the town if their campaign towards Japan became bogged down or concluded, or if the size of Australian forces on the island was increased.
In late April 1944, the US Army's 40th Infantry Division assumed responsibility for garrisoning the Allied positions in New Britain, moving from Guadalcanal. The use of an Australian formation to relieve the Marines had been considered at this time, but due to a lack of suitable shipping and equipment interoperability issues, the decision was made to temporarily defer this. The 40th Infantry Division subsequently maintained positions around Talasea–Cape Hoskins, Arawe and Cape Gloucester and did not conduct offensive operations against the Japanese forces in the east of the island. As a result, the fighting on New Britain devolved largely into what historian Peter Dennis has called a "tacit truce" with the US and Japanese troops being separated by a "no man's land", in which Australian-led native troops from the Allied Intelligence Bureau (AIB) conducted a small-scale guerilla campaign.
In mid-1944, the Australian Government agreed to take on responsibility for military operations in the British and Australian territories and mandates in the South-West Pacific, including Australian New Guinea, of which New Britain was part, and the northern Solomon Islands. US troops were reallocated for operations to secure the Philippines. In August, the Australian Army's 5th Division, under Major General Alan Ramsay, was selected to replace the 40th Infantry Division on New Britain. The formation was to assume responsibility for the island on 1 November. Instead of maintaining the American bases in western New Britain the Australians planned to operate closer to the Japanese forces around the Gazelle Peninsula. 
By the time of the Australian take over, Allied intelligence estimated that the Japanese forces on New Britain amounted to 38,000 personnel, but in actuality there were 93,000 Japanese on the island. The Japanese personnel were focused upon sustaining themselves, with rice-growing and gardening being undertaken to supplement the limited supplies that were arriving. Naval and air support for the force was limited, with only two aircraft capable of action and no ships other than 150 barges that could move up to 90 personnel or 15 tons of stores.
As of April 1944, small Japanese observation posts were located along the south coast of New Britain as far west as the village of Awul, near Cape Dampier, approximately east of Arawe. There was an observation post at Jacquinot Bay. A larger force was stationed at Henry Reid Bay in the Wide Bay area. During that month the AIB force responsible for the south coast of New Britain was ordered to destroy all the Japanese posts to the west of Henry Reid Bay. This unit comprised about 140 native troops led by five Australian officers and ten Australian non-commissioned officers.
Preliminary operations.
In mid-April, the coastwatching station at Jacquinot Bay was the first Japanese position to be attacked. A platoon of native troops led by two Australians attacked it after learning that it was lightly defended. Five of the ten IJN personnel stationed there were killed in the initial attack, and four of the survivors were hunted down and killed. The other Japanese sailor was taken prisoner. Two other Japanese sailors were taken prisoner in the Jacquinot Bay region on 22 April after the native troops attacked a barge. The three prisoners were evacuated by an American PT boat later that month. The IJN command responsible for New Britain was never able to determine the fate of the Jacquinot Bay garrison or the barge.
Broader operations against the Japanese observation posts began in June. On the fifth of the month a patrol of American troops attacked the position at Awul, causing its garrison to retreat into the centre of the island. Other attacks by the AIB force followed, and by early September all of the Japanese observation posts west of Wide Bay had been destroyed. Japanese troops conducted small-scale reprisals against the native population of the Wide Bay hinterland, and the AIB officers attempted to persuade the population of this area to move inland before more severe reprisals were conducted.
During the operations along the south coast of New Britain, the AIB officers sought to discourage the Japanese from moving west of the Wide Bay area by circulating rumours among the local population that a large Australian base had been established at Jacquinot Bay. In reality no such base existed at this time. The AIB force continued to make guerilla attacks on Japanese positions until early October, when it was ordered to cease offensive operations and concentrate on intelligence gathering ahead of the Australian landing at Jacquinot Bay. The AIB's operations from June to October were assisted on occasion by Allied air attacks and naval bombardments.
Preparations.
To support the 5th Division's planned offensive operations the Australian high command in the New Guinea area, New Guinea Force, determined that a logistics base needed to be established closer to Rabaul than those used by the US Army forces on New Britain. At a conference held on 24 August involving the commanders of New Guinea Force and the 5th Division, it was decided to investigate whether the Talasea–Hoskins area on the north coast of New Britain and the Jacquinot Bay area on the south coast of the island could accommodate bases for the 5th Division. The 5th Division had previously been deployed to New Guinea in 1943–1944, but had been reorganised for operations on New Britain. By the time of its commitment it consisted of three infantry brigades: the 4th, 6th and 13th.
On 5 September, a party of 105 personnel from the 5th Division, 2/8th Commando Squadron, New Guinea Force and Royal Australian Air Force (RAAF) was