After the Japanese invasion of New Guinea the Americans, aided by Australian troops, organized a series of landings and other offensive actions against the Japanese in New Guinea. The campaign was long and arduous, but by the end of 1944 the Japanese threat was contained in New Guinea. After this point the American forces moved to other fronts, leaving the Australian troops to commence mop up operations. The Japanese forces in New Guinea finally surrendered in August 1945.
In the beginning of 1942 the Japanese started their assault on the Australian-held territories of New Guinea Mandate and Papua, and on Western Guinea, which was a part of the Dutch East Indies. In the second phase of the battle, the Allied forces seized the initiative and managed to recapture the lost territories. The campaign in New Guinea lasted until the Japanese surrender in 1945.
The next phase of the Pacific campaign was driven by expediency and characterized by improvisation. The US, committed to ‘Germany first’, planned to dispatch most of its available troop strength to fight in North Africa. General Douglas MacArthur, in Australia, lacked men to launch the assault on Rabaul which he favored. Instead, Australian troops, slowly reinforced by Americans, were committed to frustrate Japanese designs on the vast jungle island of Papua New Guinea. Separated from the northern tip of Australia by only two hundred miles of sea, this became the scene of one of the grimmest struggles of the war.
Early in the New Guinea campaign, MacArthur revealed some unique leadership characteristics. MacArthur’s staff tried to convince themselves and others that MacArthur was a military genius. Some people believed it, but many did not. MacArthur’s paranoia, lust for personal publicity, political ambition, structured and comfortable lifestyle, and hypochondria were well known in the army. His erratic performance in the Philippines should have led to his relief and retirement, but, instead, the Medal of Honor and a flood of media attention, encouraged by President Roosevelt, diverted attention from America’s military disasters.
The Japanese began establishing small forces on the eastern coast of the island in March 1942, with the intention of seizing Port Moresby, capital of Australian-ruled Papua, two hundred miles distant on the south-west shore. American success at Midway denied the Japanese any prospect of a swift capture of New Guinea through seaborne landings. Tokyo’s local commander, Col. Tsuji, made a personal decision instead to secure the island the hard way, by an overland advance, and forged an order supposedly from Imperial headquarters to authorize his operation.
The only possible resumption of the offensive to which the Japanese now turned was an overland assault to seize Port Moresby. Because the new Allied command in the South Pacific was building up slowly, the Japanese were able to get first to the northern end of the land route, the Kokoda trail. Landing an army contingent at Buna, they proceeded to push back the Australians across the rugged Owen Stanley Mountains.
The Japanese eventually covered 120 miles out of the 150 necessary to reach their objective, over the Owen Stanley Mountains. A new air commander was sent out, and that commander, General George C. Kenney, soon brought about dramatic improvements. The air strikes he commanded helped the Australians to finally bring the Japanese to a halt. By then the Japanese were themselves so weakened from losses and the horrendous terrain that they were told to halt by their headquarters. From places within sight of Port Moresby the Japanese began a withdrawal back across the Kokoda trail; few ever saw home.
If the Japanese had beaten the Allies to Buna, the reverse was true at the southeastern end of New Guinea. There Australian troops with some American engineers and anti-aircraft units had been landed at Milne Bay to begin establishing what became one of the great shipping and air bases in the South Pacific. When Japanese Marines came ashore they were met by the entrenched Allied force. In two weeks of bitter fighting the Japanese were crushed, losing over 2,000 men and evacuating only a remnant. For the first time in the war, a major Japanese amphibious force had been defeated ashore. The tide was turning against Japan on New Guinea even before her weary land forces had begun to trudge back over the Kokoda trail.
The follow-up to the victory at Milne Bay did not go smoothly. Heavy Allied casualties due both to Japanese weapons and to disease, the sacking of both United States and Australian generals and a proclamation of victory from MacArthur's headquarters long before the campaign was over, characterized a battle that did not end in victory for the Allies until January 1943.
The Japanese defeat at Buna-Gona made it all the more important to hold on in central New Guinea. The agreed strategy, formalized in a new war plan, provided for the defense of the existing perimeter in the south. The Japanese would try hard to rebuild the strength of their forces on New Guinea, depleted by the Australian-US victory in Papua, in the hope of holding on to the northern portion of the great island, thereby protecting the approaches to their major base at Rabaul. These efforts were thwarted by quick Allied moves, greatly aided by an airlift arranged by the 5th Air Force, and by a crushing defeat inflicted by the same air force on a major Japanese reinforcement effort in the Battle of the Bismarck Sea.
American and Australian troops in a series of carefully planned and coordinated moves crushed the main Japanese forces in the Lae and Salamaua area. A combined US-Australian force, assisted by a parachute assault to capture a nearby area for an airfield, succeeded in taking both Lae and Salamaua with the surviving Japanese defenders driven into the jungle. The Allies were greatly assisted by a surprise attack of the 5th Air Force which destroyed almost 200 Japanese planes on the ground at Wewak, thus depriving the Japanese in central New Guinea of air cover for several weeks in the face of the Allied offensive.
Hardly had the main bases of Japanese power in central New Guinea been taken than the 9th Australian Division landed at Finschhafen at the tip of the Huon peninsula and took the town and harbor after ten days of bitter fighting. They thus anchored an Allied presence on the New Guinea side of the straits separating that great island from New Britain, the long curving island with Rabaul, Japan's major bastion in the Southwest Pacific, at the other end. By the time Finschhafen was secured, the other wing of the ‘Cartwheel’ operation to isolate Rabaul, the offensive in the Solomons, had also made major advances.
In a series of policy conferences in Tokyo, the Japanese agreed on a somewhat modified strategy for the defense of their Pacific empire. They drew a new defensive line — including Bougainville and parts of New Guinea — which they would hold as long as at all possible, with that defense strengthened by extensive reinforcements which were now to be sent to the Southern Pacific. This would hopefully buy them enough time to refit and rearm their armies and air force.
While the Japanese were getting ready to reinforce their 35,000 soldiers on the threatened island with additional troops from New Britain and naval air units from the Combined Fleet, the Allies carried out several diversionary operations to mislead the Japanese and throw them off balance. The main assault went into a lightly defended and unlikely portion of Bougainville, Empress Augusta Bay. Attacks by planes and warships on the Japanese air bases at both ends of the island threw off the defenders, who were totally surprised by the 3rd Marine Division's landing. The Japanese counterattack mounted by naval forces already on the way from Rabaul was defeated by the smaller but better handled forces of Admiral Aaron Stanton Merrill.
A final operation in the process concerning Rabaul was the landing of the 1st Marine Division and army units at Cape Gloucester near the western end of New Britain. This operation helped contain the Japanese forces of over 100,000 men who remained on both New Britain and the nearby island of New Ireland until 1945. Rabaul had been isolated and largely neutralized. ‘Cartwheel’, the operation designed to convert the Japanese base at Rabaul from an effective bastion in defense and a potential basis for new offensives into a wasting liability, had been completed.
In a gamble which paid off handsomely, the Americans had landed a reconnaissance force in the Admiralty Islands on short notice. Bypassing the bulk of Japanese units in central New Guinea, the Americans had then surprised them by going 600 miles up the coast to Hollandia, soon making this small community in the Dutch portion of New Guinea into a major base. Because it turned out that the land nearby was not suitable for airfields which could carry heavy bombers, MacArthur quickly threw his forces forward, landing on the little island of Wakde to seize its airfield, and launching an assault on Biak. The American troops eventually destroyed the Japanese force on Biak and secured the airfields.
The purpose of seizing the Biak airfields and those on Wakde had been to provide air support for the last offensive on New Guinea—the seizure of points in the northwest, the area called Vogelkop. American troops landed first on Noemfoor and then at Sansapor, establishing themselves quickly while the substantial and recently reinforced Japanese garrison in the area, the equivalent of two divisions, faded into the jungle until the 1945 surrender rather than fight it out.
Of the remaining Japanese forces only General Adachi Hataao's 18th Army would attempt a major counter-offensive against Aitape, one of the American coastal strong points. Beaten off with losses of over 10,000 men, the 18th Army, like the Japanese 2nd Army in northwest New Guinea, was left behind by the war. Their containment was turned over to the Australians. General Thomas Blarney ordered aggressive operations by the Australians. Only on New Britain, where the Japanese greatly outnumbered the Australians, was a policy of containment rather than constant attacks followed. The Japanese forces surrendered in September 1945 after the atomic bombings of Hiroshima and Nagasaki.
The New Guinea campaign remains a focus of controversy. It inflicted misery on all its participants, many of whom doubted its usefulness, especially in the later stages. For a few brief weeks before the Coral Sea and Midway, it seemed a possible Japanese stepping stone to Australia, but by June 1942 this prospect was already dead. In some respects, the campaign became thereafter an Asian counterpart of Britain’s North African and 1942–44 Burma operations.