Operation Battle of Milne Bay

The 'Battle of Milne Bay', otherwise known as the 'Battle of Rabi', was fought between Japanese and Australian forces for Milne Bay, at the south-eastern tip of Papua, as a result of the Japanese 'Re' operation (25 August/7 September 1942).

In this undertaking, Imperial Japanese navy troops of the special naval landing forces organisation, together with two small tanks, landed in Milne Bay and attacked the Allied airfields which had been established on the eastern tip of New Guinea. As a result of poor intelligence, the Japanese had wholly miscalculated the size of the predominantly Australian garrison and, believing that the airfields were defended by only two or three companies, initially landed a force roughly equivalent in size to one battalion on 25 August 1942. The Allies, forewarned by 'Ultra' intelligence, had in fact heavily reinforced the garrison.

Despite suffering a significant setback at the outset, when part of their small invasion force had its landing craft destroyed by Royal Australian Air Force aircraft as they attempted to land on the coast behind the Australian defenders, the Japanese quickly pushed inland and began their advance towards the airfields. Heavy fighting followed as the Japanese encountered the Australian militia troops constituting the first line of defence. These troops were steadily pushed back, but the Australians then brought forward veteran units of the 2nd Australian Imperial Force which the Japanese had not expected. Allied air superiority helped tip the balance, providing close support to troops in combat and targeting Japanese logistics. Finding themselves strongly outnumbered, lacking supplies and suffering heavy casualties, the Japanese forces withdrew and the fighting ended on 7 September.

The battle is often described as the first major battle of the war in the Pacific in which Allied troops decisively defeated Japanese land forces. Although Japanese land forces had experienced local setbacks elsewhere in the Pacific earlier in the war, unlike that at Milne Bay, these earlier actions had not forced them to withdraw completely and abandon their strategic objective. Nor did they have such a profound impact upon the thoughts and perceptions of the Allies toward the Japanese, and their prospects for victory. The 'Battle of Milne Bay' thus revealed the limits of the Japanese capacity for expansion using relatively small forces in the face of increasingly larger Allied troop concentrations and command of the air. As a result of the battle, Allied morale was boosted and Milne Bay was developed into a major Allied base, which was used to mount subsequent operations in the region.

Milne Bay is a sheltered 97-sq mile (250-km˛) bay at the eastern tip of the Territory of Papua. The bay is 22 miles (35 km) long and 10 miles (16 km) wide, and its waters are deep enough for large ships to enter. The coastal area is flat with good air approaches, and therefore suitable for airstrips, although it is intercut by mangrove swamps and the many tributaries of local rivers. As a result of its swampy nature and its high rainfall, the latter amounting to some 200 in (5080 mm) per year, the area is rife with malaria and prone to flooding. After flooding, the coastal plains become 'virtually impassable quagmires of glutinous mud', and the ground is not suited for development. The bay is bounded to its north and south by the Stirling Ranges, which at places rise to 3,000 to 5,000 ft (915 to 1525 m) and are covered in kunai grass and dense scrubland. The main area of firm ground suitable for construction and development is found directly at the head of the bay. In 1942 this area was occupied by plantations of oil palms, coconuts and cocoa, as well as a number of jetties and villages, connected by what was described as a 'modest ''road'' system', that was actually nothing more than an earth track 33 to 39 ft (10 to 12 m) wide. The area was sparsely populated, although there were a number of villages along the track. Of these, Ahioma was situated farthest to the east, and together with Gili Gili in the west, it bounded Lilihoa, Waga Waga, Goroni, KB Mission, Rabi and Kilarbo.

The Japanese thrust into the Pacific region had started early in December 1941 with attacks against British and Commonwealth forces in the 'Battle of Hong Kong' and the 'E' (ii) campaign to take Malaya, and against the US Pacific Fleet, much of which was caught at anchor in Pearl Harbor in the 'Ai' operation by carrierborne warplanes. The Japanese advanced rapidly to the south, overwhelming resistance in Malaya, capturing Singapore in February 1942, and successfully occupying the Dutch East Indies, Timor and New Britain, on the last of which they established their major base at Rabaul. While a Japanese 'Mo' naval operation to take Port Moresby on the south coast of Papua was defeated in the 'Battle of the Coral Sea' in May, elsewhere US forces in the Philippine islands group capitulated, and Japanese forces advanced toward north-eastern India through Burma.

Although the Japanese had been checked in the 'Battle of the Coral Sea', another attempt at capturing Port Moresby was anticipated. The Allied supreme commander of the South-West Pacific Area, General Douglas MacArthur, decided to establish air bases for the defence of Port Moresby. To the west, he authorised the construction of an air base at Merauke in Dutch New Guinea, while another, codenamed 'Boston', was authorised in the area to the east in the largely unexplored Abau-Mullins Harbour area on 20 May. Any Japanese force approaching Port Moresby by sea would have to sail past these bases, whose aircraft would in all probability detect them early enough to make possible attacks before their neared Port Moresby. But the base in the east had other advantages too. Bombers flying missions against Rabaul and other Japanese bases to the north from there would not have to overfly the difficult Owen Stanley mountain range, and would not be subject to the vagaries of the weather and air turbulence over these mountains. For that reason, an airstrip suitable for heavy bombers was desired so that they could stage there from Port Moresby and bases in northern Australia.

The Allied commander-in-chief of the Allied Land Forces, General Sir Thomas Blamey, selected a garrison for 'Boston' on 24 May. The troops were informed that their mission was only to defend against Japanese raids, and in the event of a major attack they were to destroy everything of value and withdraw. The 'Boston' project fell through, as a reconnaissance of the area gave an unfavourable report, and Milne Bay was suggested as a more suitable alternative site. A party of 12 Americans and Australians set out to explore Milne Bay in a Consolidated PBY four-engined flying boat on 8 June, and was impressed by the flat areas, the roads and the jetties, all of which would facilitate air base construction. On receipt of the party’s favourable report, MacArthur’s headquarters cancelled 'Boston' on 11 June and substituted Milne Bay, which was given the codename 'Fall River'. The use of existing place names as codenames proved to be unwise, as some supplies were mistakenly sent to the real Fall River, Massachusetts, in the north-eastern USA.

The first Australian troops reached Milne Bay from Port Moresby in the Dutch KPM line ships Karsik and Bontekoe, escorted by the Australian sloop Warrego and corvette Ballarat on 25 June. Karsik docked at a pontoon wharf that had been hastily constructed from petrol drums by Papuan workers, who had been recruited by the Australian New Guinea Administration Unit and then assisted in unloading the ships. The troops included two and a half companies and a machine gun platoon of the 55th Battalion of Brigadier W. E. Smith’s 14th Brigade, the 9th Light Anti-Aircraft Battery with eight Bofors 40-mm guns, one platoon of the US 101st Coast Artillery Battalion (Anti-Aircraft) with eight -5=in (12.7-mm) machine guns, and two 3.7-in (94-mm) anti-aircraft guns of the 23rd Heavy Anti-Aircraft Battery. Company E of the 46th Engineers of the US Army Corps of Engineers arrived on Bontekoe with air base construction equipment. Some 29 KPM ships had escaped to Australia after the fall of the Dutch East Indies. These vessels were manned by Dutch and Javanese crews, and were the lifeline of the garrison at Milne Bay, making approximately two out of every three voyages there during the campaign, the remainder being by Australian, British and US ships. Five KPM ships were to be lost during the fighting in Papua.

Work on the first airfield, which became known as No. 1 Airstrip, began on 8 June, with the area near Gili Gili being cleared by Papuan workers under the supervision of ANGAU and by US 96th Engineer Separate Battalion personnel. Company E of the 46th Engineers began work on the site during 30 June. In addition to the runway, the engineers had to build camouflaged dispersal areas for 32 fighters, taxiways and accommodation for 500 men. To support the air base and the garrison, a platoon was diverted to working on the docks and roads. Although the channels in Milne Bay allowed deep-draught ships to approach within 40 ft (12 m) of the shore, they had to be unloaded onto pontoons and the stores manhandled onto vehicles, an especially labour-intensive process.

Three Curtiss Kittyhawk single-engined fighters of the RAAF’s No. 76 Squadron landed on the airstrip on 22 July, and more aircraft of the same unit and also the RAAF’s No. 75 Squadron arrived on 25 July. They found that only 4,950 by 80 ft (1510 by 25 m) of the 6,000 by 100-ft (1830 by 30l.5-m) runway was covered with Marston Matting, and that water frequently covered he runway. as they landed, aircraft sometimes skidded off the runway and became bogged.

With No. 1 Airstrip operational, work began on two more airfields. Some 5,000 coconut palms were removed for No. 2 Airstrip, and the site was levelled and graded, but its use first required the construction of at least two 60-ft (18-m) bridges, so work moved to No. 3 Airstrip near Kilarbo. Its construction was undertaken by the 2/43rd Engineers less Company E, which arrived on 4 August. That day Japanese aircraft began to bomb and strafe Milne Bay, concentrating their efforts on attacking the airfields and the engineers. Four Mitsubishi A6M Reisen 'Zero' single-engined fighters and a dive-bomber attacked No. 1 Airstrip, where one Kittyhawk was destroyed on the ground, while another Kittyhawk of No. 76 Squadron shot down the dive-bomber. Following this, the Australians established a radar system to provide early warning. On 11 August, 22 Kittyhawk fighters intercepted 12 A6M fighters. Despite their numerical advantage, the Australians lost three Kittyhawk fighters, while claiming four A6M fighters shot down.

On 11 July, troops of Brigadier J. Field’s 7th Brigade started to arrive to bolster the garrison. The brigade comprised the 9th, 25th and 61st Battalions, militia units from Queensland. They brought with them guns of the 4th Battery of the 101st Anti-Tank Regiment, the 2/6th Heavy Anti-Aircraft Battery, and the 2/9th Light Anti-Aircraft Battery, along with the first Australian engineer unit, the 24th Field Company. Field assumed command of Milne Force, a task force with operational control over all Allied air, land and naval forces in the area, but only when an attack was imminent. Field reported directly to Blamey’s Allied Land Forces in Brisbane rather than New Guinea Force in Port Moresby, and his most urgent tasks were of an engineering nature. While the US engineers built the airstrips and wharves, the Australians worked on the roads and accommodation, and the small force of sappers had to be augmented by infantry and Papuan labourers.

Although malaria was known to be endemic in the Milne Bay area, precautions taken against the disease were haphazard. Men wore shorts and kept their sleeves rolled up. Their mosquito repellent cream was ineffective, quinine was in short supply and many men arrived without their mosquito nets, which were stowed deep in the ships' holds and took several days to unload. A daily dosage of 10 grains of quinine was prescribed, but Field’s troops were told not to take their quinine until they had been in the area for a week. By this time, many had become infected with the disease. The Director of Medicine at Allied Land Forces Headquarters was Brigadier N. H. Fairley, an expert on tropical medicine and, when he visited Port Moresby in June, he was highly 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 therefore ensured 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. Some of the equipment was lost or ruined in transit, however, and the danger from malaria was not yet appreciated at Milne Bay.

The 55th Battalion’s companies had already been hard hit by malaria and other tropical diseases, and were withdrawn and sent back to Port Moresby early in August, but the garrison was further reinforced with 2nd Australian Imperial Force troops of Brigadier G. F. Wootten’s 18th Brigade of the 7th Division, which began arriving on 12 August and would be complete only on 21 August. This veteran brigade, which had fought in the siege of Tobruk earlier in the war,comprised the 2/9th, 2/10th and 2/12th Battalions. Anti-aircraft and artillery support was provided by the 9th Battery of the 2/3rd Light Anti-Aircraft Regiment, the US 709th Anti-Aircraft Battery and the 9th Battery of the 2/5th Field Regiment, while various signals and logistics troops provided further support.

With two brigades now at Milne Bay, Major General C. A. Clowes was appointed to command Milne Force, which was placed under the control of New Guinea Force, now commanded by Lieutenant General S.F. Rowell, on 12 August. Clowes’s headquarters was formed in Sydney at the end of July and was flown to Milne Bay. Clowes himself arrived with some of his staff on 13 August, but had to wait until the rest arrived before he could formally assume command of Milne Force on 22 August. By this time there were 7,459 Australian and 1,365 US Army personnel at Milne Bay, of whom about 4,500 were infantry. There were also about 600 RAAF personnel. Clowes assigned the inexperienced 7th Brigade a defensive role, guarding key points around Milne Bay from seaborne or airborne attack, and kept the veteran 18th Brigade in reserve ready to counterattack any threatened sector. Lacking accurate maps and finding that the signals equipment was unreliable in the conditions, the Australian command and control system consisted largely of cable telephones, or where there was not enough linee, runners. The soft ground made movement by road and even on foot difficult.

Japanese aircraft soon discovered the Allied presence at Milne Bay. This was clearly a threat to Japanese plans for another seaborne advance on Port Moresby, which was to start with a landing on Samarai island in the China Strait, not far from Milne Bay. On 31 July the commander of the Japanese 17th Army, Lieutenant General Harukichi Hyakutake, requested that Vice Admiral Gunichi Mikawa’s 8th Fleet instead take the new Allied base at Milne Bay. Mikawa agreed and created the 'Re' operation, which was scheduled for the middle of August. 'Re' received a high priority after aircraft of the 25th Air Flotilla discovered the new Milne Bay airfields on 4 August, but was then postponed as a result of the US 'Watchtower' landings on Guadalcanal on 7 August.

Under the misconception that the airfields were defended by only two or three companies of Australian infantry, totalling between 300 and 600 men, the initial Japanese assault force was based on only some 1,250 men. The Imperial Japanese army was unwilling to conduct the operation as it feared that landing barges sent to the area would be attacked by Allied aircraft. Following a dispute between officers of the Imperial Japanese army and navy, it was agreed that the navy would have responsibility for the landing, and as a result, the assault force was drawn from the Japanese naval infantry, known as the Kaigun Rikusentai (special naval landing forces). Some 612 naval troops of the 5th Kure Special Naval Landing Force, led by Commander Masajiro Hayashi, were scheduled to land on the eastern coast near a point identified by the Japanese as 'Rabi', along with 197 men from the 5th Sasebo Special Naval Landing Force led by Lieutenant Fujikawa. It was planned that a further 350 personnel from the 10th Special Naval Landing Force, along with 100 men of the 2nd Air Advance Party, would land from barges on the northern coast of the peninsula at Taupota, in Goodenough Bay, where it would advance over the Stirling mountain range to attack the Australians from the rear. Following the battle, the chief-of-staff of the Japanese Combined Fleet, Vice Admiral Matome Ugaki, assessed that the landing force was not of high calibre as it contained many 30/35-year-old men who were not fully fit and had 'inferior fighting spirit'. Naval support was to be provided by Rear Admiral Mitsuharu Matsuyama’s 18th Cruiser Division. The Japanese enjoyed some initial advantage in the form of possessing two Type 95 light tanks, but after an initial attack these tanks became marooned in the mud and abandoned. The Japanese also had control of the sea during the night, allowing reinforcement and evacuation.

Offsetting the Japanese tactical advantages, the Allies had the benefit of the strategic advantage of possessing superior intelligence about the Japanese intentions. The Japanese knew very little about Allied forces at Milne Bay, while the Allies received advance warning that the Japanese were planning an invasion. In the middle of July, codebreakers under the command of Commander Eric Nave informed MacArthur that toward the end of August the Japanese planned to attack Milne Bay, and provided detailed information about the numbers of men to be expected, which units would be involved, their standard of training, and the names of the ships that the Japanese had allocated to the operation. MacArthur’s intelligence chief, Brigadier General Charles A. Willoughby, had anticipated a Japanese reaction against Milne Force, and interpreted the Japanese reconnaissance of 4 August as foreshadowing an operation. After Allied Naval Forces 'Ultra' signals intelligence decrypted a message that disclosed that a Japanese submarine picquet line had been established to cover the approaches to Milne Bay, Willoughby predicted that an attack was imminent. In response, MacArthur rushed Wooten’s 18th Brigade to Milne Bay. Major General George C. Kenney, the commander of the Allied Air Forces, South-West Pacific Area, ordered an increase in the number of air patrols over the likely Japanese invasion routes, and additionally ordered pre-emptive air attacks against the Japanese airfields at Buna on 24 and 25 August, which reduced to a mere six the number of Japanese fighters available to support 'Re'.

Over the course of 23 and 24 August, aircraft of the 25th Air Flotilla carried out preparatory bombing around the airfield at Rabi. The main Japanese invasion force departed Rabaul on New Britain island on 24 August, under Matsuyama’s command, at 07.00. The force comprised the light cruisers Tenryu and Tatsuta and the destroyers Urakaze, Tanikaze and Hamakaze as well as the transports Nankai Maru and Kinai Maru and the submarine chasers CH-22 and CH-24.

At 08.30 on 24 August, the Milne Bay headquarters was alerted by an RAAF Lockheed Hudson twin-engined bomber and coastal reconnaissance aeroplane, near Kitava island off the Trobriand islands group, and coastwatchers that a Japanese convoy was approaching the Milne Bay area. The Australian destroyr Arunta, which was escorting the transport Tasman, left the Milne Bay area and steamed for Port Moresby after learning of the invasion force. Reports of a second Japanese convoy, comprising seven barges which had sailed from Buna carrying the force that would land at Taupota, were also received at this time. In response to this sighting, after the initially poor weather had cleared, 12 RAAF Kittyhawk fighters were scrambled at 12.00. The barges were spotted on the beach near Goodenough island, where the 350 troops of the 5th Sasebo Special Naval Landing Force, under the command of Commander Tsukioka, had gone ashore to rest. The Australian pilots then strafed the barges and, over the course of two hours, destroyed all of them and thus stranded their former occupants.

After the initial sighting, the main invasion force, comprising the heavy naval screening force and the two transports, remained elusive until the morning of 25 August. In an effort to intercept it, US Boeing B-17 Flying Fortress four-engined heavy bombers operating from bases at Mareeba and Charters Towers in Queensland, were despatched, although they were unable to complete their mission as the weather deteriorated. Later in the afternoon, a number of Kittyhawk fighters and one Hudson bomber strafed the convoy and attempted to hit the transports with 250-lb (113-kg) bombs near Rabi island. The convoy suffered only limited damage and no ships were sunk. After this, as a result of the withdrawal of Arunta and Tasman, the only Allied naval presence in the area, an RAAF tender was sent to the bay to serve as a picket, ready to provide early warning of the Japanese approach.

Meanwhile, earlier in the day, Clowes had decided to shorten his lines and ordered that D Company of the 61st Battalion, which had been sent to Akioma in the east, to withdraw back behind B Company at KB Mission and reposition itself at the No. 3 Airstrip at Gili Gili. However, a shortage of water craft delayed D Company’s departure until the evening of 25 August after the luggers Bronzewing, Elevala and Dadosee had been requisitioned. At about 22.30. the Japanese main force of more than 1,000 men and two Type 95 Ha-Go tanks, had made landfall near Waga Waga, on the northern shore of the bay; as a result of a navigational error, they came ashore about 1.85 miles (3 km) to the east of the planned place, which put it farther away from the objective. Nevertheless, the Japanese quickly sent out patrols to secure the area, rounding up local villagers and establishing a beach-head.

Later in the same evening, two of the small water craft which D Company were using to withdraw to Gili Gili, encountered the Japanese landing force, and in the firefight that followed, Elevala was forced to beach and its occupants compelled to the jungle on foot, eventually reaching Gili Gili some time later; the other vessel, Bronzewing, was holed and of its passengers 11 were killed either in the engagement or by the Japanese following their capture.

By dawn on 26 August, advancing to the west along the coast with armoured support, the Japanese had reached the main position held by B Company, 61st Battalion, around KB Mission. The Japanese force moved through the jungle at the edge of the coastal track, with the two light tanks in the lead. Although they lacked anti-tank weapons, the Australians were able to turn back the Japanese attack. At this stage, the Japanese suffered a serious setback when their base area was heavily attacked in daylight by RAAF Kittyhawk and one Hudson aircraft, along with North American B-25 Mitchell and Martin B-26 Marauder twin-engined medium bombers as well as B-17 heavy bombers of Kenney’s US 5th Army Air Force. A number of Japanese troops were killed in the attack, while a large quantity of supplies was destroyed, as too were a number of the landing barges beached near the KB Mission. Aside from severely hampering the Japanese supply system, the destruction of the landing barges also prevented their use to outflank the Australian battalions. The Japanese had no air cover as the fighters based at Buna, which were to have patrolled over Milne Bay, had been shot down by Allied fighters shortly after they took off and other aircraft based at Rabaul were forced to turn back in the face of adverse weather.

The Japanese were nonetheless still pressing on the 61st Battalion’s positions throughout the day. Field, who had command responsibility for this area, decided to send two platoons of the 25th Battalion to provide support. Later, the 61st Battalion’s remaining two companies, together with their mortar platoon, were also despatched. The muddy track meant that the Australians were unable to move anti-tank guns into position, but as a stop-gap measure, quantities of sticky bombs and anti-tank mines were moved up to the forward units. At 16.45, with air and artillery support, the Australians launched a minor attack on the Japanese forward positions located about 600 yards (550 m) to the east of the mission, pushing the Japanese back another 200 yards (185 m). Wearied by the day’s fighting, though, theypulled back to Motieau, to the west of the mission.

The Australians then attempted to break contact and withdraw towards a creek line where they hoped to establish a defensive line as darkness came. The Japanese remained in close contact with the Australians, however, harassing their rear elements. The men of B Company then sought to establish their position, while the 2/10th Battalion made preparations to move eastward toward Ahioma, passing through the lines of the 25th and 61st Battalions. In the early evening, Japanese ships shelled the Australian positions and the, at 22.00. the Japanese launched a heavy attack which continued sporadically through the night. By 04.00, the Japanese had started to employ infiltration and deception techniques to try to outflank the Australian positions. Anticipating an armoured attack at dawn, the Australians withdrew back to the Gama river, 1 mile (1.6 km) to the west. During the night, the destroyer Hamakaze entered Milne Bay to establish contact with the Japanese troops and land supplies. The landing force had been out of radio contact since 14.00. and the destroyer was unable to raise it with either radio or signalling lamps. As a result, Hamakaze departed Milne Bay at 02.30 without landing any supplies.

Shortly after dawn, in the air, a Japanese force consisting of eight Aichi D3A single-engined dive-bombers escorted by 12 A6M fighters attacked the Allied airfield at Gili Gili. One of the attacking aircraft was shot down, while only a small amount of damage was inflicted. Meanwhile, around the KB Mission as the Japanese undertook a reconnaissance of the positions, the 2/10th Battalion, of just 420 men, was ordered to the Gama river. This undertaking was badly planned and did not have a clear purpose: it was launched as both a reconnaissance in force and as a counterattack, but evolved into an attempt to establish a blocking force at KB Mission. Moreover, while the Australians had no knowledge of the strength or intentions of the Japanese, no force would be able to reinforce the battalion once it moved outside the main defensive lines near the airstrips. The 2/10th Battalion’s forward patrols made contact with the 61st Battalion at about 10.30 on 27 August and, upon arrival at around 17.00, began to establish its position. Possessing only limited entrenching tools, the battalion found the going difficult. At this point, the men of the 25th and 61st Battalion were ordered to pull back, having lost 18 men killed and a further 18 wounded, along with an unknown number missing.

At 20.00, the Japanese sent two Type 95 tanks with bright headlights into the plantation. The men of the 2/10th Battalion tried to disable the tanks with sticky bombs, but in the humid conditions the bombs did not adhere to the Japanese vehicles. In the fighting that followed over the course of 150 minutes, the Australians sustained heavy casualties. Receiving indirect fire support from the 2/5th Field Regiment’s 25-pdr gun/howitzers sited near Gili Gili, they repelled four frontal attacks. However, by 00.00 the Japanese had penetrated into the Australian position and in the confusion the 2/10th Battalion withdrew in some disorder to a number of scattered positions on the western bank of the Gama river, which they had reached by about 02.00 on 28 August. Another attack by tank-mounted infantry forced them back still farther, however, moving back through the 61st and 25th Battalions toward No. 3 Airstrip, which was still under construction to the south of Kilarbo. During the brief engagement around KB Mission, the Australians had lost 43 men killed and another 26 wounded.

As the 2/10th Battalion pulled back, the 25th Battalion, which had moved forward from Gili Gili to relieve the 61st Battalion, deployed around the airstrip and at Rabi, Duira creek and Kilarbo, laying mines in key locations. The airstrip proved a perfect defensive location, for it offered a wide, clear field of fire, while at its end, thick mud served to prevent the movement of Japanese tanks. At about dawn the Japanese advance reached the airstrip and, under the cover of field artillery and mortars, the Japanese launched an attack. Although the Australians did not know it, the tanks that were supporting the attack became stuck in the mud and were subsequently abandoned, and were later discovered by an Australian patrol on 29 August. Meanwhile, men of the 25th and 61st Battalions, along with Americans from the 709th Anti-Aircraft Battery, turned back the attacking Japanese infantry. Further strafing by Kittyhawk fighters followed, and the Japanese were forced to fall back 1.2 miles (2 km) to the east of Rabi.

For the next two days there was a lull in the fighting, and during this time the Australians consolidated their defences. Despite being seriously depleted, the 61st Battalion was ordered back to the perimeter around the airstrip, subsequently deploying around Stephen’s Ridge and linking with the 25th Battalion’s positions between the coast and Wehria Creek. Fire support was provided by mortars of the 25th Battalion along with Vickers machine guns of the 61st Battalion and the 0.3- and 0.5-in (7.72- and 12.7-mm) machine guns mounted on the US half-tracked vehicles. The US engineers and anti-aircraft gunners became the first US troops to engage in ground combat in New Guinea.

Elsewhere, the 2/12th Battalion started to move forward from Waigani to enable it to join the fighting later as a counterattack force. Along with the 2/9th Battalion, the 2/12th Battalion was subsequently tasked to carry out an attack from No. 3 Airstrip to KB Mission. Meanwhile, the Japanese also sought to reconfigure their forces and Mikawa decided to strengthen the forces that were already ashore. These reinforcements, comprising 567 men of the 3rd Kure Special Naval Landing Force and 200 of the 5th Yokosuka Special Naval Landing Force, departed Rabaul on 28 August. At about 16.30 an RAAF patrol aeroplane spotted the Japanese convoy, which comprised one cruiser and nine destroyers, and reported the fact to the Allied headquarters. Believing that further landings were imminent, Clowes cancelled his plans to begin a counterattack with the troops of the 18th Brigade. Orders were also passed for the 30 Kittyhawk fighters at Gili Gili to be flown off to Port Moresby in case the Japanese succeeded in breaking through to the airfield. No attack took place, though, and consequently during the early morning on 29 August the aircraft returned, albeit minus two machines which had crashed during the move.

The Japanese convoy arrived off Waga Waga at 20.l15 on 29 August, and began landing troops and supplies. While this was taking place the warships shelled Allied positions around Gili Gili and by 23.30 had completed their landing. The shelling was not significant, however, and there were no casualties from it. Throughout 30 August, the Australians carried out patrol operations while the Japanese laid up in the jungle in preparation for an attack that night.

Later that night the Japanese began forming up along the track at the eastern end of No. 3 Airstrip by the sea,and at 03.00 on 31 August launched their attack. Advancing over open ground and illuminated by Australian flares, the first Japanese attack was repelled by the heavy machine gun and mortar fire of the 25th and 61st Battalions as well as the 46th Engineer General Service Regiment and the artillery fire of the Australian 2/5th Field Regiment. A further two banzai charges were attempted, but they too met the same fate, with heavy Japanese casualties, including Hayashi, the Japanese commander. At this point, Commander Minoru Yano, who had arrived with the Japanese reinforcements on 29 August, succeeded Hayashi and, after the survivors of the attack had re-formed in the dead ground around Poin Creek, he led them about 200 yards (185 m) north of the airstrip in an attempt to outflank the 61st Battalion’s positions on Stephen’s Ridge. After running into a platoon of Australians who engaged them with Bren light machine guns, the Japanese withdrew just before dawn. The Japanese survivors of this attack were shocked by the heavy firepower the Allied forces had been able to deploy, and the assault force was left in a state of disarray.

Early on 31 August, the 2/12th Battalion began moving towards KB Mission, with D Company leading the way and struggling through muddy conditions along the track, which had been turned into a quagmire by the heavy rain and equally heavy traffic over it. After passing through the 61st Battalion’s position, at around 09.00 the battalion began its counterattack along the northern coast of Milne Bay. As they moved, the Australians were harassed by snipers and ambush parties. They also encountered several Japanese soldiers who tried to lure the Australians in close for attack by pretending to be dead. In response, some Australians systematically bayoneted and shot the bodies of the Japanese dead. At 12.00, the 9th Battalion, a militia unit of the 7th Brigade despatched two companies to occupy some of the ground that the 2/12th Battalion had regained around No. 3 Airstrip and KB Mission.

Making slow progress against considerable resistance, the Australians reached KB Mission late in the day. A Japanese force remained there, and the Australians attacked with fixed bayonets. In the resulting combat, 60 Japanese were killed or wounded. The Australians were then able to establish themselves firmly at the mission. Meanwhile, the 9th Battalion’s two companies took position at Kilarbo and between the Gama river and Homo creek with orders to establish blocking positions to allow the 2/12th Battalion to continue its advance during the morning of the following day.

That night, a force of around 300 Japanese, which had been falling back since it had run into the 61st Battalion on Stephen’s Ridge, encountered positions manned by the 2/12th and 9th Battalions around the Gama river. In a surprise attack, the Australians inflicted heavy casualties on the Japanese. After the battle, the Australians estimated that as many as 90 Japanese had been killed. After this, the Japanese began to employ infiltration techniques in an attempt to pass through the numerous listening posts that had been set up along the side of the track which formed the front of one side of the 2/12th's Battalion’s position. Elsewhere, at KB Mission, from about 20.00 they switched to harassment tactics in an effort to distract the Australians and assist their comrades seeking to break through the Australian positions from the Gama river. This lasted throughout the night.

On the following morning of 1 September, the 2/12th Battalion went over to the offensive once again, while a force of seven Kittyhawk fighters attacked the Japanese headquarters around Waga Waga. By this time, the Japanese had abandoned their attempt to reach the airfields and instead sought only to hold off the Australians long enough to be evacuated. This was not known by the Allies, who were in fact expecting the Japanese to undertake further offensive action. In this regard, the 2/9th Battalion, initially with orders to join the 2/12th Battalion’s counterattack, was delayed by an extra day after an erroneous intelligence report from MacArthur’s headquarters had warned Clowes of a renewed Japanese attack, which persuaded the Austraian commander briefly to adopt a more defensive posture. The attack did not occur and, as a result, on 2 September the 2/9th Battalion was moved by barge up to KB Mission. The next day it took over from the 2/12th Battalion and led the Australian advance.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. We will together calmly defend our position to the death. We pray for absolute victory for the empire and for long-lasting fortune in battle for you all.'

The terrain in this part of the bay offered significant advantage to the defence, lined as it was with numerous creeks which slowed movement and obscured firing lanes. Throughout 3 September, the 2/9th Battalion came up against significant resistance: in one engagement around the middle of the morning along a stream to the west of Elevada creek the battalion lost 34 men killed or wounded as it tried to force its way across a creek. Engaged by sustained machine gun fire, the two assault platoons withdrew across the creek while elements of another company that was in support moved to the northern flank. Launching their assault, the Australians found that the Japanese had withdrawn, leaving about 20 dead.

After this, the 2/9th Battalion advanced another 500 yards (460 m), reaching Sanderson’s Bay, before deciding to set up its night location. During the night, Japanese ships again shelled Australian positions on the bay’s northern shore, but without causing any casualties among the defenders.

On 4 September, the Australian advance continued as the 2/9th Battalion moved along the coast on each side of the coastal track. After about one hour, the leading company encountered a Japanese defensive position at Goroni. Throughout the day the Australians worked to outflank the position before launching an attack at 15.15. During this action, one of the 2/9th Battalion’s sections was held up by fire from three Japanese machine gun positions. Corporal John French ordered the other members of the section to take cover before he attacked and destroyed two of the machine guns with grenades. French then attacked the third position with his Thompson sub-machine gun. The Japanese firing ceased and the Australian section advanced to find that the machine gunners had been killed and that French had died in front of the third position. By the end of 4 September, the Japanese force had only 50 fully fit men: all the other surviving troops were either incapacitated or could offer only token resistance. In addition, the commanders of all the Japanese companies had been killed and only three or four platoon leaders remained.

Following the fighting on 31 August, the Japanese forces ashore had reported the situation to their headquarters at Rabaul. In response, plans were made to send the 'Aoba' Detachment, which comprised the army’s 4th Regiment and one artillery company, to Rabi to complete the capture of the airfield. The 'Aoba' Detachment was not scheduled to arrive until 11 September, so it was planned in the meantime to reinforce Yano’s force with 130 men of the 5th Yokosuka Special Naval Landing Force. An abortive attempt was made to land these troops on 2 September and then again on 4 September. By that time, however, as further reports were received by the Japanese headquarters, it had become clear that Yano’s troops would not be able to hold out until the 'Aoba' Detachment arrived. As a result, on 5 September, the Japanese high command ordered a withdrawal. This was carried out from the sea that evening.

On 5 September, six Bristol Beaufort twin-engined torpedo bombers of the RAAF’s No. 100 Squadron had arrived at Milne Bay. Three Bristol Beaufighter twin-engined heavy fighters of the RAAF’s No. 30 Squadron, the first unit to receive this type, joined them on the following day. The Beaufort bombers were tasked with providing additional support against further landings and undertaking anti-shipping missions. On 6 September, the Allied offensive reached the Japanese landing force’s main camp, fighting a number of minor actions against small groups left behind after the evacuation.

Shortly after 22.00 on 6 September, as the freighter Anshun was continuing unloading cargo under her lights, the port came under fire from the Japanese light cruiser Tenryu and the destroyer Arashi, and Anshun received about 10 hits from the cruiser and rolled onto her side. The Japanese ships also shelled shore positions at Gili Gili and Waga Waga, and illuminated, but did not fire on, the hospital ship Manunda which was displaying her hospital ship colours and lights. During the next night, two Japanese warships, a light cruiser and a destroyer, shelled Australian positions for 15 minutes and caused a number of casualties before exiting the bay. This was the |Imperial Japanese navy’s final act in the battle. During the mopping-up operations that followed, patrols by Australian troops tracked down and killed a number of Japanese troops who were attempting to trek overland to Buna.

The 350 Japanese troops who had been stranded on Goodenough island after their barges were destroyed on 24 August were not rescued until a time late in October. An attempt to evacuate the force on 11 September ended in failure when the two destroyers assigned to the task were attacked by USAAF aircraft, resulting in the loss of Yayoi. Two more attempts to rescue the force on 13 and 22 September were unsuccessful, though supplies were air-dropped on the island. A submarine landed more supplies and evacuated 50 sick personnel on 3 and 13 October. As part of the preparations for the attack on Buna and Gona, the 2/12th Battalion was assigned to secure Goodenough island on 19 October. The battalion landed three days later, and a series of small engagements on 23 and 24 October cost the Australian force 13 men killed and 19 wounded, while the Japanese suffered 20 men killed and 15 wounded. The remaining Japanese troops were evacuated by two barges to nearby Fergusson island on the night of 24 October, and the light cruiser Tenryu rescued them two days later. After securing the island, the 2/12th Battalion began work on building Vivigani airfield on its eastern coast.

The Allies continued to develop the base area at Milne Bay in support of the counter-offensive along the northern coast of Papua and New Guinea. The American base became US Advanced Sub Base A on 21 April 1943, US Advance Base A on 14 August and US Base A on 15 November. Its Australian counterpart, the Milne Bay Base Sub Area, was formed on 14 June 1943. Two 155-mm (6.1-in) coastal guns with searchlights were provided to protect the base from naval threats. New roads were built and the existing roads upgraded to make them passable in wet conditions. By June 1944, there were more than 100 miles (160 km) of road in the area.

A bitumen-surfaced second runway was built at No. 1 Airstrip by the RAAF’s No. 6 Mobile Works Squadron, after which the original runway was used only for emergencies and taxiing. The minefield around No. 3 Airstrip was lifted and the airstrip was completed, with revetments and hardstands for 70 medium bombers. A new wharf, known as Liles' wharf after the US engineer who supervised its construction, was built in September and October 1942. This was capable of handling Liberty ships, and after this ships could sail direct to Milne Bay from the USA, reducing the pressure on Australian ports and saving two or three days' sailing time in addition to the time formerly taken to unload and then reload the cargo on smaller ships in those ports. PT-boats were based at Milne Bay from December 1942, with PT-boat overhaul facilities, a destroyer base, a trans-shipment and staging area and a station hospital.

On 14 April 1943, the Allied base was attacked by 188 Japanese aircraft during the Japanese 'I' air offensive. The base’s anti-aircraft defences were limited, but a force of 24 RAAF Kittyhawk fighters was available to respond to the attack. Minor damage was inflicted on the supply dumps around the airfields, while one British ship, Gorgon, was damaged and Van Heemskerk, a Dutch transport carrying US troops, was sunk. At least three Allied aircraft were shot down, while the Japanese lost seven aircraft. Milne Bay was later used as a staging area for the 'Postern' landing at Lae in September 1943 and for the 'Backhander' landing which started the New Britain campaign in December 1943. The base at Milne Bay remained operational until the end of the war.

During the Australian counterattack at Milne Bay, the advancing troops found evidence that the Japanese had committed a number of war crimes, specifically the execution of both prisoners of war and civilians. None of the 36 Australian troops who were captured by the Japanese survived: several were found to have been executed, with some showing signs of having been mutilated as well. In addition, at least 59 civilians were murdered between 25 August and 6 September: included in this were a number of Papuan women who were sexually assaulted before being killed. The war crimes committed at Milne Bay had the effect of hardening Australian soldiers' attitudes towards Japanese troops for the remainder of the war.

The Australians estimated Japanese casualties at about 700 to 750 men killed in action, and a Japanese source reported 625 killed in action. Of the 1,943 Japanese soldiers landed at Milne Bay, ships of the 18th Cruiser Division evacuated 1,318 men, including 311 wounded. The Australians suffered 373 casualties, of which 167 were killed or missing. The US forces lost 14 men killed and several wounded.

Although Allied casualties during the battle had been light, in the wake of the battle Milne Bay suffered an epidemic of malaria that posed a threat to the base as great as that from the Japanese attack. more than one in six men of the Milne Force, including Clowes, came down with the disease. The incidence of malaria soared to 33 per 1,000 per week in September, and to 82 per 1,000 per week in December. At this rate, the whole force could have been incapacitated in a matter of months. It placed enormous strain on the medical units and the supplies of anti-malarial drugs. The chief pathologist of New Guinea Force, Lieutenant Colonel E. Ford, went to see Blamey, who was now in personal command of New Guinea Force, and told him that 1,000 men and a large quantity of anti-malarial supplies were urgently required at Milne Bay to avert a disaster. Blamey took a personal interest in the matter and expedited supply shipments, and also ensured that the required personnel were made available. The arrival of quantities of the new drug atabrine allowed this more effective drug to be substituted for quinine. The incidence of malaria dropped dramatically after December, the month in which atabrine became the official Australian prophylactic drug, and by March 1943 the crisis had passed. After this, the incidence of malaria among the garrison at Milne Bay was similar to other bases in Papua and New Guinea.

Strategically, as a result of the fighting around Milne Bay Japanese operations within the region were limited. The defeat of 'Re' kept the Japanese from bypassing the holding action that the Australians were conducting on the Kokoda Track. Milne Bay revealed 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. Japanese commanders were then forced to change their plans in the region, shifting the focus toward repelling the US forces that had landed on Guadalcanal, while maintaining a smaller effort around Buna and Gona under Major General Tomitaro Horii. The Japanese planned, once they had retaken Guadalcanal, to reinforce Horii’s forces and launch a reinvigorated attack on the Australians around Port Moresby. In the end, subsequent defeats at Buna and Gona and on Guadalcanal made these plans irrelevant as the Allies gained the ascendency in the region throughout the later part of 1942, and the Japanese were forced to fall back to the northern coast of New Guinea. In the aftermath of the battle, a large amount of intelligence was also gained by the Allies, providing their planners with a better understanding of the strengths and weaknesses of the Japanese and their equipment. It also demonstrated that the Australian militia units were effective fighting forces.

The most significant result, though, was the effect that the victory had on the morale of Allied servicemen elsewhere in Asia and the Pacific, especially those on the Kokoda Track, and British troops fighting in Burma. Although the Japanese had previously suffered minor local defeats, such as their first landing on Wake island and the 'Battle of the Tenaru' on Guadalcanal, these actions, unlike the 'Battle of Milne Bay', had not resulted in complete Japanese withdrawal and the abandonment of the military campaign. The Allied victory at Milne Bay therefore represented Japan’s first 'full-scale defeat on land'.

Within Australia, initial public reaction to the victory was one of cautious optimism. An article in The Canberra Times early in September 1942 labelled the victory a 'tonic surprise', and while highlighting the example as a portent of future battlefield success by Australian forces in the region, also pointed out the task that lay ahead of the Australians in New Guinea remained a 'major problem'. Most significantly, though, it highlighted the importance of morale in turning the tide in the war, describing it as 'the bridge that must carry all the vast and complicated effort being directed towards victory'.

Among individual Australian soldiers, the news of the victory helped to dispel some of the notions about the invincibility of the Japanese soldier that had developed in the minds of Allied soldiers following the defeats in the early part of 1942, and which had impacted on Allied planning up to that point. Some of these notions would remain until the end of the war, but the news of Milne Bay allowed many soldiers to rationalise the Japanese soldiers' past victories as being the result of tangible factors, such as numerical superiority, that could be overcome, rather than innate factors associated with the intangible qualities of the Japanese soldier that were not so easily overcome. After this, among the Allies there was 'a sense that fortune’s wheel was turning', and although leaders such as Blamey emphasised the difficulties that lay ahead, a feeling of confidence in eventual victory emerged. MacArthur warned the US Department of War that success was attributable to good intelligence that allowed him to concentrate a superior force at Milne Bay, and might not be repeatable.