The campaign was initiated by the Allies in late 1943 as part of a major offensive which aimed to neutralise the important Japanese base at Rabaul, the capital of New Britain, and was conducted in two phases between December 1943 and the end of the war in August 1945.

Initial fighting on New Britain took place around the western end of the island in December 1943 and January 1944, with US forces landing and securing bases around Arawe and Cape Gloucester.

[5] On 1 July 1942, 849 POWs and 208 civilian men who had been captured on New Britain were killed when the Montevideo Maru was torpedoed by an American submarine en route to Japan.

[6] These forces lacked naval and air support,[14] and were increasingly isolated and eventually cut-off from resupply due to Allied interdiction efforts, which meant that the garrison was largely left to its own devices.

Simultaneously, the units assigned to the South West Pacific Area, commanded by General Douglas MacArthur, were to secure Lae and Salamaua on the north coast of New Guinea.

Under this plan, MacArthur's forces were to establish airfields on two islands off the coast of New Guinea, capture the Huon Peninsula region of the mainland and land in western New Britain.

[18] While the initial plans for Operation Cartwheel directed MacArthur to capture Rabaul, in June 1943 the Joint Chiefs of Staff decided that this was unnecessary as the Japanese base there could be neutralized by blockade and aerial bombardment.

MacArthur initially opposed this change in plans, but it was endorsed by the British and United States Combined Chiefs of Staff during the Quebec Conference in August.

However, the planned landing at Gasmata was cancelled in November due to concerns over the Japanese reinforcing the region and its proximity to the airfields at Rabaul, as well as the terrain being judged too swampy.

Instead, on 21 November it was decided to capture the Arawe area on the south-west coast of New Britain to establish a base for PT boats and hopefully divert Japanese attention away from the main landing at Cape Gloucester.

[31] The 17th Division was selected to provide troops for this purpose; the main body of this unit arrived in Rabaul from China on 4 and 5 October, having suffered around 1,400 casualties due to submarine and air attacks while en route to New Britain.

[32] For the Arawe operation, the Director Task Force, under the command of Brigadier General Julian Cunningham,[28] concentrated on Goodenough Island where they carried out training prior to embarking on 13 December 1943.

Two small advanced elements set off almost immediately under the cover of darkness with orders to destroy a radio transmitter on Pilelo Island to the south-east and to sever the track leading towards the peninsula around Umtingalu village.

[40] A heavy aerial bombardment was directed against Cape Gloucester's garrison in the weeks before the landing which destroyed many of the fixed defences and affected the soldiers' morale.

In January 1944, the Allies sought to press their advantage further, launching another Dexterity operation on the New Guinea coast with a landing at Saidor as the Huon Peninsula was cleared by Australian and US forces.

[47] In the months following the operations to secure Arawe and Cape Gloucester, there was only limited fighting on New Britain as Japanese forces largely chose to avoid combat during this period and continued their withdrawal towards Rabaul.

[54] In April 1944, once Arawe and Cape Gloucester had been secured, the US 40th Infantry Division under Major General Rapp Brush[55] arrived to relieve the Marines and cavalrymen that had landed in December 1943.

Instead, the Japanese judged that the Allies would advance slowly across New Britain towards the town and attack it only if their campaign towards Japan became bogged down or concluded, or if the size of Australian forces on the island was increased.

While this was incorrect by a factor of two, Allied assessments of Japanese intentions were more accurate, with planners believing that Imamura's force would adopt a defensive posture, remaining largely inside the fortifications that had been established around Rabaul.

[61] In fact Japanese combat strength was approximately 69,000 men, including 53,000 army troops and 16,000 sailors, and while they were mainly located in the Gazelle Peninsula in the north around Rabaul, there were watching-stations established as far forward as Awul.

Allied bombing had heavily reduced Japanese air and naval forces to the extent that there were only two operational aircraft left, and the only vessels that remained were 150 barges that could move small amounts of supplies or troops around the coast.

Nevertheless, it was decided that the Australians would carry out a limited offensive, consisting largely of patrol actions, with the goal of advancing beyond the western tip of the island where the US garrison had remained.

[68] After this, the Australians on the north coast pushed their line towards Open Bay, establishing an outpost around Baia and patrolling the Mavelo Plantation, during which several minor skirmishes were fought.

[66] After this, a series of engagements took place over a six-week period to reduce the main Japanese position around Mount Sugi, commencing with the 19th Infantry Battalion's assault across the Wulwut River on 5 March.

[71] The position around Mount Sugi, which stretched across a number of ridges to the west of the Wulwut, was strongly defended with mortars, machine guns and pillboxes, and heavy rain also frustrated Australian attempts to reduce the Japanese stronghold.

In the months that followed, the Australians mounted a series of patrols aimed at maintaining the line around the neck of the Gazelle Peninsula to prevent any attempt by the Japanese to break out from Rabaul.

[67] The 2/2nd Commando Squadron conducted a patrol which penetrated close to Rabaul, and judged that the terrain was so rough it would not be possible for large Japanese units to move over it to attack the Australian forces.

[79] US Army historian John Miller also concluded that the operations to secure Arawe and Cape Gloucester "were probably not essential to the reduction of Rabaul or the approach to the Philippines", while there were some benefits to the offensive in western New Britain and comparatively few casualties.

[83] Peter Charlton also regarded the Australian operations as successful, but was critical of both the decision to deploy the 5th Division against a much more powerful Japanese force and the limited support provided for the campaign.

[85] Eustace Keogh concurs with this assessment, arguing that any offensive would have lacked strategic purpose without sufficient naval and air support, which at the time was unavailable to the Japanese.