US engineers, protected by Australian infantry and artillery, had been constructing airfields in the area since June 1942. By late August, when the Japanese mounted their offensive, Milne Force numbered almost 9,000 ground troops, of which half were infantry. Two Australian fighter squadrons, at the base since July, were supported at the time of the offensive by detachments of bombers and torpedo-bombers.

Japanese planners felt that the US counter-offensive at Guadalcanal in the Solomon Islands in early August could be contained. Nevertheless, they delayed the offensive against Rabi, which was the name of the planned landing point in Milne Bay, until their 25th Air Squadron was operational at Buna on the north coast of Papua. The Japanese 8th Fleet underestimated the Allied strength at Milne Bay, and initially committed approximately 800 Special Naval Landing Party (SNLP) troops with approximately 360 base establishment and support troops to a direct landing at Rabi, and a 350 strong SNLP to an overland attack on the Milne Bay airstrips from Taupota on the north coast. In a blow to the overall Japanese strategy, this latter force was stranded en route at Goodenough Island when Allied Kittyhawks destroyed their transport barges, effectively ruling them out of the operation.

Japanese air attacks on the base at Milne Bay began early in the month as a prelude to the successful landing of the main force during the night of 25 August. However, Allied attacks on Buna and Japanese losses over Milne Bay severely restricted the Japanese air units’ ability to provide cover for the invasion transports, and their offensive effectiveness.

The difficulty of the terrain compounded Japanese progress towards the airstrips to the west of the landing point. Stubborn resistance from the Australian defenders, and the effective coordination of ground and air forces by the Allies prompted the 8th Fleet to deploy a further 750 SNLP troops, which landed during the night of 29 August at Waga Waga, 6 kilometres east of Rabi. Despite this, heavy Japanese losses on 31 August from allied troops well entrenched near No.3 Strip further thwarted attempts to advance. Furthermore, destruction of Japanese barges by Australian Kittyhawks from No. 75 and No. 76 Squadrons removed the ability to move troops along the coast under the cover of darkness.

From 1 September, the Japanese were gradually forced east back along the coast. Poor weather had repeatedly prevented Japanese planes from Buna and Kavieng from supporting the Rabi offensive, and despite some effective support by sea, the decision to cancel planned reinforcements and to withdraw completely was taken by 8th Fleet command on 5 September. Two thirds of the total strength of approximately 2,000 were evacuated over the following nights. The remaining 600 were either killed in battle or perished attempting to return overland to Buna. The Allied losses were far less, with 161 killed and a further 212 injured.

The Japanese offensive had completely failed in the face of a superior, strongly defended Allied force. The defeat would have been quicker had not the Australian commander, Major General Cyril Clowes, been cautious in his approach to the initial Japanese incursions, not knowing if further landings would compromise his flanks and rear positions. The conditions also conspired against the Japanese advance on the airfields, with their light tanks quickly immobilised by the boggy roads, and their troops worn down by the incessant rain. Pinned down during the day by effectively directed Allied air attacks and infrequent friendly air cover, and with no means to outflank the defenders by sea, the Japanese advance quickly turned into a fighting retreat to consolidate prior to the arrival of expected reinforcements. However, the redeployment of these fresh troops due to the worsening situation in the Solomons left little hope of a successful end to the campaign.

The failure by the Japanese to secure the strategic airfields at Milne Bay had dire consequences for the planned invasion of Port Moresby. Even if Major General HORII’s South Seas Force could successfully cross the Owen Stanley Range, there would be little chance of support and reinforcement from the sea-route without a forward base and close air support. On the contrary, the Allies were now free to expand their presence at Milne Bay, and to use it as a springboard along the north coast towards Buna. This, combined with the deteriorating situation at Guadalcanal, greatly influenced the decision by Japanese command at Rabaul to abandon offensives against Port Moresby, and effectively signalled a turning point in the New Guinea campaign.

Contributed by Steven Bullard (AJRP)

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