Milne Bay showed the limits of Japanese capability to expand using relatively small forces in the face of increasingly larger Allied troop concentrations and command of the air.

In 1942 this area was occupied by plantations of palm oil, coconuts and cocoa,[9] as well as a number of jetties and villages, connected by what was described by Major Sydney Elliott-Smith of the Australian New Guinea Administrative Unit (ANGAU) as a "modest 'road' system"[5] that was, in actuality, only a dirt track 10–12 metres (33–39 ft) wide.

[13] They rapidly advanced south, overwhelming resistance in Malaya, capturing Singapore in February 1942, and successfully occupying Timor, Rabaul and the Dutch East Indies.

The Allied Supreme Commander of the South West Pacific Area, General Douglas MacArthur, decided to establish airbases to protect Port Moresby.

Bombers flying missions to Rabaul and other Japanese bases to the north from there would not have to overfly the Owen Stanley Range, and would not be subject to the vagaries of the weather and air turbulence over the mountains.

Karsik docked at a pontoon wharf that had been hastily constructed from petrol drums by Papuan workers, who had been recruited by ANGAU and who subsequently assisted in unloading the ships.

They were manned by Dutch and Javanese crews, and were the lifeline of the garrison at Milne Bay, making roughly two out of every three voyages there during the campaign, the remainder being by Australian, British and US ships.

[23] Although the channels in Milne Bay allowed deep draught ships to approach within 40 feet (12 m) of the shore, they had to be unloaded onto pontoons and the stores manhandled onto vehicles, a labour-intensive process.

He visited Port Moresby in June, and was alarmed at the ineffectiveness of the measures being taken to combat the disease, which he realised was capable of destroying the entire Allied force in Papua.

He made sure that the 110th Casualty Clearing Station left Brisbane for Milne Bay with a fully equipped pathological laboratory and a large quantity of anti-malarial supplies, including 200,000 quinine tablets.

[39] Lacking accurate maps and finding that their signals equipment was unreliable in the conditions, the Australian command and control system consisted largely of cable telephones, or where there was not enough line available, runners.

On 31 July the commander of the Japanese XVII Army, Lieutenant General Harukichi Hyakutake, requested that Vice Admiral Gunichi Mikawa's 8th Fleet capture the new Allied base at Milne Bay instead.

[50] Following the battle, the chief of staff of the Japanese Combined Fleet, Vice Admiral Matome Ugaki, assessed that the landing force was not of a high calibre as it contained many 30- to 35-year-old soldiers who were not fully fit and had "inferior fighting spirit".

[55] HMAS Arunta – escorting the transport SS Tasman – left the Milne Bay area and sailed for Port Moresby after learning of the invasion force.

[57] After this, due to the withdrawal of the only Allied naval presence in the area – Arunta and Tasman – an RAAF tender was sent to act as a picket in the bay, ready to provide early warning of the approaching Japanese.

[62] By dawn of 26 August, advancing west along the coast with armoured support, the Japanese had reached the main position manned by troops from B Company, 61st Infantry Battalion, around KB Mission.

[76] The 2/10th's forward patrols made contact with the 61st Infantry Battalion at around 10:30 am on 27 August and,[72] upon arrival at around 5:00 pm,[77] they began to establish their position; with only limited entrenching tools, they found the going difficult.

[83] The airstrip proved a perfect defensive location, offering a wide, clear field of fire, while at its end, thick mud served to prevent the movement of Japanese tanks.

[102][103] At this point, Commander Minoru Yano, who had arrived with the Japanese reinforcements on 29 August, took over from Hayashi, and after the survivors of the attack had reformed in the dead ground around Poin Creek, he led them about 200 yards (180 m) north of the airstrip in an attempt to outflank the 61st Infantry Battalion's positions on Stephen's Ridge.

In this regard, the 2/9th, initially with orders to join the 2/12th's counterattack, was delayed an extra day after an erroneous intelligence report from MacArthur's headquarters warning Clowes of a renewed Japanese attack forced him to briefly adopt a more defensive posture.

[118] With the Japanese position at Milne Bay close to collapse, on 2 September Yano sent a radio message to the headquarters of the 8th Fleet which stated: "[w]e have reached the worst possible situation.

The terrain in this part of the bay offered significant advantage to defending forces, lined as it was with numerous creeks which slowed movement and obscured firing lanes.

[122] Engaged with sustained machine gun fire, the two assault platoons withdrew back across the creek while elements of another company that was in support moved to the northern flank.

He was posthumously awarded the Victoria Cross for his "cool courage and disregard of his own personal safety" which "saved members of his section from heavy casualties and was responsible for the successful conclusion of the attack".

In response, plans were made to send the Aoba Detachment, which comprised the Army's 4th Infantry Regiment and an artillery company,[130][131] to Rabi to complete the capture of the airfield.

[3] On 6 September, the Allied offensive reached the main camp of the Japanese landing force, fighting a number of minor actions against small groups that had been left behind after the evacuation.

[135][136] The next night, two Japanese warships – a cruiser and a destroyer – bombarded Australian positions causing a number of casualties for 15 minutes before leaving the bay; it would be their final act in the battle.

[158] Milne Bay showed the limits of Japanese capability to expand using relatively small forces in the face of increasingly larger Allied troop concentrations and command of the air.

[160] In the end, subsequent defeats at Buna–Gona and on Guadalcanal did not allow them to implement these plans, as the Allies gained the ascendency in the region throughout late 1942 and the Japanese were forced to fall back to the northern coast of New Guinea.

[169] After this, amongst the Allies there was "a sense that fortune's wheel was turning",[168] and although leaders such as Blamey emphasised the difficulties that lay ahead, a feeling of confidence in eventual victory emerged.