The New Guinea campaign of the Pacific War lasted from January 1942 until the end of the war in August 1945. During the initial phase in early 1942, the Empire of Japan invaded the Australian-administered territories of the New Guinea Mandate (23 January) and Papua (8 March) and overran western New Guinea (beginning 29/30 March), which was a part of the Netherlands East Indies. During the second phase, lasting from late 1942 until the Japanese surrender, the Allies—consisting primarily of Australian and US forces—cleared the Japanese first from Papua, then the Mandate and finally from the Dutch colony.
The campaign resulted in a crushing defeat and heavy losses for the Empire of Japan. As in most Pacific War campaigns, disease and starvation claimed more Japanese lives than enemy action. Most Japanese troops never even came into contact with Allied forces, and were instead simply cut off and subjected to an effective blockade by the US Navy. Garrisons were effectively besieged and denied shipments of food and medical supplies, and as a result, some claim that 97% of Japanese deaths in this campaign were from non-combat causes.
According to John Laffin, the campaign "was arguably the most arduous fought by any Allied troops during World War II".
The colonial capital of Port Moresby on the south coast of Papua was the strategic key for the Japanese in this area of operations. Capturing it would both neutralize the Allies' principal forward base and serve as a springboard for a possible invasion of Australia. For the same reasons, General Douglas MacArthur, Supreme Commander Allied Forces South West Pacific Area was determined to hold it. MacArthur was further determined to conquer all of New Guinea in his progress toward the eventual recapture of the Philippines. General Headquarters Southwest Pacific Area Operational Instruction No.7 of 25 May 1942, issued by Commander-Allied-Forces, General Douglas MacArthur, placed all Australian and US Army, Air Force and Navy Forces in the Port Moresby Area under the control of New Guinea Force.
Due north of Port Moresby, on the northeast coast of Papua, are Huon Gulf and the Huon Peninsula. The Japanese entered Lae and Salamaua, two locations on Huon Gulf, unopposed in early March 1942. MacArthur would have liked to deny this area to the Japanese, but he had neither sufficient air nor naval forces to undertake a counterlanding. The Japanese at Rabaul and other bases on New Britain would have easily overwhelmed any such effort (by mid-September, MacArthur's entire naval force under Vice Admiral Arthur S. Carpender consisted entirely of 5 cruisers, 8 destroyers, 20 submarines 7 small craft). The only Allied response was a bombing raid of Lae and Salamaua by aircraft flying over the Owen Stanley Range from the carriers USS Lexington and USS Yorktown, leading the Japanese to reinforce these sites.
Japanese attempt on Port Moresby
Operation Mo was the designation given by the Japanese to their initial plan to take possession of Port Moresby. Their operation plan decreed a five-pronged attack: one task force to establish a seaplane base at Tulagi in the lower Solomons, one to establish a seaplane base in the Louisiade Archipelago off the eastern tip of New Guinea, one of transports to land troops near Port Moresby, one with a light carrier to cover the landing, and one with two fleet carriers to sink the Allied forces sent in response. In the resulting 4–8 May 1942 Battle of the Coral Sea, the Allies suffered higher losses in ships, but achieved a crucial strategic victory by turning the Japanese landing force back, thereby removing the threat to Port Moresby, at least for the time being.
After this failure, the Japanese decided on a longer term, two-pronged assault for their next attempt on Port Moresby. Forward positions would first be established at Milne Bay, located in the forked eastern end of the Papuan peninsula, and at Buna, a village on the northeast coast of Papua about halfway between Huon Gulf and Milne Bay. Simultaneous operations from these two locations, one amphibious and one overland, would converge on the target city.
"[T]he Owen Stanley Range is a jagged, precipitous obstacle covered with tropical rainforest up to the pass at 6500-foot elevation, and with moss like a thick wet sponge up to the highest peaks, 13,000 feet above the sea. The Kokoda Trail [was] suitable for splay-toed Papuan aborigines but a torture to modern soldiers carrying heavy equipment..."
– Samuel Eliot Morison, Breaking the Bismarcks Barrier, p. 34
Buna was easily taken as the Allies had no military presence there (MacArthur wisely chose not to attempt an occupation by paratroopers since any such force would have been easily wiped out by the Japanese). The Japanese occupied the village with an initial force of 1,500 on 21 July and by 22 August had 11,430 men under arms at Buna. Then began the grueling Kokoda Track campaign, a brutal experience for both the Japanese and Australian troops involved. On 17 September, the Japanese had reached the village of Ioribaiwa, just 30 kilometres (20 mi) from the Allied airdrome at Port Moresby. The Australians held firm and began their counterdrive on 26 September. "...the Japanese retreat down the Kokoda Trail had turned into a rout. Thousands perished from starvation and disease; the commanding general, Horii, was drowned." Thus was the overland threat to Port Moresby permanently removed.
Since Port Moresby was the only port supporting operations in Papua, its defence was critical to the campaign. The air defences consisted of P-39 and P-40 fighters. RAAF radar could not provide sufficient warning of Japanese attacks, so reliance was placed on coastwatchers and spotters in the hills until an American radar unit arrived in September with better equipment. Japanese bombers were often escorted by fighters which came in at 30,000 ft (9,100 m)—too high to be intercepted by the P-39s and P-40s—giving the Japanese an altitude advantage in air combat. The cost to the Allied fighters was high. By June, 20–25 P-39s had been lost in air combat, while three more had been destroyed on the ground and eight had been destroyed in landings by accident. The Australian and American anti-aircraft gunners of the Composite Anti-Aircraft Defences played a crucial part. The gunners got a lot of practice; Port Moresby suffered its 78th raid on 17 August 1942. A gradual improvement in their numbers and skill forced the Japanese bombers up to higher altitude, where they were less accurate, and then, in August, to raiding by night.
Although RAAF PBY Catalinas and Lockheed Hudsons were based at Port Moresby, because of the Japanese air attacks, long-range bombers like B-17s, B-25s, and B-26s could not be safely based there and were instead staged through from bases in Australia. This resulted in considerable fatigue for the air crews. Due to USAAF doctrine and a lack of long-range escorts, long-range bomber raids on targets like Rabaul went in unescorted and suffered heavy losses, prompting severe criticism of Lieutenant GeneralGeorge Brett by war correspondents for misusing his forces. But fighters did provide cover for the transports, and for bombers when their targets were within range. Aircraft based at Port Moresby and Milne Bay fought to prevent the Japanese from basing aircraft at Buna, and attempted to prevent the Japanese reinforcement of the Buna area. As the Japanese ground forces pressed toward Port Moresby, the Allied Air Forces struck supply points along the Kokoda Track. Japanese makeshift bridges were attacked by P-40s with 500 lb (230 kg) bombs.
"Thenceforth, the Battle of Milne Bay became an infantry struggle in the sopping jungle carried on mostly at night under pouring rain. The Aussies were fighting mad, for they had found some of their captured fellows tied to trees and bayoneted to death, surmounted by the placard, 'It took them a long time to die'."
– Samuel Eliot Morison, Breaking the Bismarcks Barrier, p. 38
While it was beyond MacArthur's capabilities to deny Buna to the Japanese, the same could not be said of Milne Bay, which was easily accessible by Allied naval forces. In early June, US Army engineers, Australian infantry and an anti-aircraft battery were landed near the Lever Brothers coconut plantation at Gili Gili, and work was begun on an airfield. By 22 August, about 8,500 Australians and 1,300 Americans were on site. The Japanese arrived and the 25 August – 7 September Battle of Milne Bay was underway. Historian Samuel Eliot Morison summed up the results this way:
...the enemy had shot his bolt; he never showed up again in these waters. The Battle for Milne Bay was a small one as World War II engagements went, but very important. Except for the initial assault on Wake Island, this was the first time that a Japanese amphibious operation had been thrown for a loss ... Furthermore, the Milne Bay affair demonstrated once again that an amphibious assault without air protection, and with an assault force inferior to that of the defenders, could not succeed.
The D'Entrecasteaux Islands lie directly off the northeast coast of the lower portion of the Papuan peninsula. The westernmost island of this group, Goodenough, had been occupied in August 1942 by 353 stranded troops from bombed Japanese landing craft. The destroyer Yayoi, sent to recover these men, was itself bombed and sunk on 11 September. A force of 800 Australian troops landed on 22 October on either side of the Japanese position. Beleaguered, the survivors of the Japanese garrison were evacuated by submarine on the night of 26 October. The Allies proceeded to turn the island into an air base.
"In the swamp country which surrounded the area were large crocodiles ... Incidence of malaria was almost one hundred per cent. At Sanananda the swamp and jungle were typhus-ridden ... crawling roots reached out into stagnant pools infested with mosquitoes and numerous crawling insects ... every foxhole filled with water. Thompson sub machine-guns jammed with the gritty mud and were unreliable in the humid atmosphere ... "
– John Vader, New Guinea: The Tide Is Stemmed, pp. 102–103
The Japanese drive to conquer all of New Guinea had been decisively stopped. MacArthur was now determined to liberate the island as a stepping-stone to the reconquest of the Philippines. MacArthur's rollback began with the 16 November 1942 – 22 January 1943 Battle of Buna-Gona. The experience of the green US 32nd Infantry Division, just out of training camp and utterly unschooled in jungle warfare, was nearly disastrous. Instances were noted of officers completely out of their depth, of men eating meals when they should have been on the firing line, even of cowardice. MacArthur relieved the division commander and on 30 November instructed Lieutenant General Robert L. Eichelberger, commander of the US I Corps, to go to the front personally with the charge "to remove all officers who won't fight ... if necessary, put sergeants in charge of battalions ... I want you to take Buna, or not come back alive."
"Also formidable was the tenacity of the enemy, who would fight to the death in these stinking holes, starving, diseased and with their dead rotting and unburied beside them."
– John Vader, New Guinea: The Tide Is Stemmed, p. 93
The Australian 7th Division under the command of Major General George Alan Vasey, along with the revitalized US 32nd Division, restarted the Allied offensive. Gona fell to the Australians on 9 December 1942, Buna to the US 32nd on 2 January 1943, and Sanananda, located between the two larger villages, fell to the Australians on 22 January.