The Battle for Milne Bay was one of the two land battles that saved Port Moresby and secured Australia from the threat of invasion. Although arguably less well known than the famous defence of the Kokoda Track, the Australian victory at Milne Bay was significant for two very important reasons. The first was that the Japanese attempt to outflank the defenders of the Track and take Port Moresby from the east failed. The second reason the defenders of Milne Bay are deservedly remembered, is that they inflicted on the Japanese their first defeat on land. The impact on Allied morale of such a feat cannot be underestimated.
The Japanese attack on Milne Bay occurred for a number of reasons. When the earlier amphibious invasion was foiled by the Battle of the Coral Sea, the Japanese resorted to land attacks. The major assault, across the Owen Stanley Ranges via the Kokoda Track, was progressing only slowly in the harsh terrain, difficult resupply conditions and in the face of vigorous Australian resistance. The Japanese decided on an ambitious outflanking manoeuvre with another thrust from the eastern end of PNG, from Milne Bay. The discovery that the Allies were constructing airfields there also encouraged the Japanese to undertake the operation. (The airfields, which were to play a central role in the battle, experienced their first air raid on 4th August.) The Japanese also planned to base air and naval assets in Milne Bay to support operations both on Kokoda and east into the islands.
The strategic importance of the Bay was understood by both sides. In addition to the 7th Australian Infantry Brigade (a Militia Brigade) that had been in the area from July, the Australians reinforced the garrison with the veteran 18th Brigade, defenders of Tobruk, in mid August. There were also over 1300 US airfield construction engineers. Together, these troops made up ‘Milne Force’. For once the Japanese, rather than General Macarthur, underestimated the size of the opposition. Japanese intelligence estimated only two or three companies were in the area, which explains the relatively small size of the invasion force – about 2,000 marines and some light tanks.
The battle began in the late evening of 25th August, when the Japanese landed between Wahahuba and Ahioma. (They had intended to land further west near Rabi, this error forcing their troops to cross an additional 11 kilometres of the appalling terrain.) Although well supported by naval gunfire, the Japanese were forced to fight hard to make progress. Troops from two Militia Battalions of the 7th Brigade, the 61st and the 25th, contested the landings (especially near K. B. Mission), causing heavy casualties. However, reinforced by another 800 Marines and with strong naval support, the Japanese began to make a steady advance westward along the coastal track. The presence of two light tanks and the Japanese use of night attacks tended to disrupt the Australian defenders who conducted a fighting retreat back to No. 3 airstrip, where the Japanese were again held on the night of the 27th.
There was lull in the fighting until a determined attack on No. 3 strip was launched in the early hours of the 31st of August. Although the Japanese launched 3 massed charges, the Australian infantry, together with troops from the US 43rd Engineer Regiment, held firm. Making no progress, dawn saw the Japanese withdraw, having lost many men to machine guns and artillery fire. At 9.00 am, the Australians launched a counter-attack, initially using one of the AIF Battalions, the 2/12th but joined later by companies from the 2/9th Battalion.
Although the enemy fought fierce rear-guard actions, over the next five days, the Australians drove the Japanese back over ten kilometres. Resistance hardened when the Japanese were pushed back to their landing point. The 2/9th Battalion, in hard fighting that saw the Corporal J.A. French win the Victoria Cross, eventually penetrated the enemy base area.
The effect of this was to convince the Japanese to withdraw and between 3rd and 6th September, the Japanese marines were withdrawn. For the first time, a Japanese amphibious landing had been resisted and repelled.
It is easy to look at the superiority of numbers enjoyed by the defenders as reasons for this unexpected success but that misrepresents the significance of this battle. Despite superior Allied troop numbers, Malaya and Singapore had fallen without trouble. The deep water in the Bay was a major advantage to the Japanese, possessing as they did complete maritime superiority at night. This enabled them to provide strong naval support to the invasion force while also offering tactical mobility along the coast. The Allied Command could not ignore the threat of a landing behind established defensive lines. Nor could it ignore the threat to their northern flanks, and many of General Clowes’ superior numbers were tied up guarding these vulnerable lines of approach. It was not clear to the Australian command at the time that the
Japanese on the coastal strip were the only enemy involved in the operation. The Japanese also possessed armour, which complicated the defence problem for the Australian commander. The advantage largely lay with the Japanese but, for the first time, they failed to capitalise on it.