By January 1943, the Americans and Australians had ejected the Japanese from Papua, New Guinea. General Douglas MacArthur, the Southwest Pacific Area (SWPA) commander, had secured an airstrip and staging base at Buna on the New Guinea north coast. But heavy U.S. casualties left the unprepared American divisions too dissipated for battle, requiring about six months to recuperate. The Australians, despite their own losses, took on the next phase against the Japanese.
Unloading supplies on the beach at Hollandia, New Guinea, April 1944.
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Despite the Japanese defeat at Buna and the heavy losses in the continuing struggle for Guadalcanal, in January 1943 Japan still held the preponderant air, naval, and ground strength in the Southwest Pacific and retained the strategic initiative in New Guinea. With these advantages, they planned to strike again for Port Moresby, their target on the south coast of Papua.
Expanding from a major air base and anchorage on the Huon Gulf at Lae (NE New Guinea) the next Japanese objective was to secure a forward air base at Wau, weakly held by the Australians, located about 150 miles west-northwest of Buna. The ability of U.S. Navy cryptanalysts to provide MacArthur with solid intelligence made it impossible for the Japanese to evade Allied countermoves to their plans. Japanese reinforcements were sent to Lae for the Wau operation, but Allied air attacks sank most the troop ships. Without reinforcements, the under strength attack on Wau was repulsed by the Australians, who were reinforced themselves using American air transports. A second Japanese attempt to reinforce Lae was again attacked and destroyed during the Battle of the Bismarck Sea (2-5 March 1943), when the U.S. Fifth Air Force and Royal Australian Air Force together with U.S. Navy small craft sank eight transports and four destroyers.
From February to June 1943 the eastern New Guinea battle zone lapsed into a stalemate as the Allies and the Japanese reinforced and replaced earlier losses. Shipping shortages created logistics and transportation bottlenecks for both sides. Neither side had the resources in early 1943 to force a decisive victory, and both expected a war of attrition to continue.
Amphibious Operations Accelerate the Pace in New Guinea
In June 1943, SWPA conducted an amphibious operation, landing at Nassau Bay, about forty miles from Lae, to threaten Japanese defenders at Salamaua, north of Nassau Bay on the approaches to Lae. As a pincer movement, while the Americans pushed along the coast, Australian troops advanced on a western axis from Wau through the Markham Valley. Although the Japanese defenders were few in number, the jungle terrain made progress extremely slow and costly. The Allies were helped by strikes on 17-18 August 1943 against the Japanese airfield at Wewak that damaged or destroyed 128 planes, 75% of the Japanese aircraft. American losses from the end of June until 12 September, when Salamaua fell, were 81 killed and 396 wounded while the Australians suffered 112 killed, 346 wounded, and 12 missing. Many others were sick or psychologically damaged from the appalling conditions. The Japanese lost more than 1,000 men.
Amphibious landings 4-6 September put Australian troops on a beachhead eighteen miles east of Lae. On 5 September American airborne troops established a new position at Nadzab, about twenty miles west of Lae. The dual operations forced the Japanese to withdraw to Finschhafen fifty miles east of Lae, which was occupied on 16 September. The Japanese evaded the Australians by a detour into the mountains, but at a terrible cost in Japanese lives.
Finschhafen was the strong point that guarded the western side of the sixty-mile-wide straits separating New Guinea and New Britain. From fortified Satelberg Ridge, high ground overlooking the entire coastline, about 3,000 Japanese waited for the Allies, ready to block any further push toward Sio.
Strategic Changes in the New Guinea Campaign
At the Quebec Conference in August 1943, the decision was made to bypass Rabaul and concentrate MacArthur's forces on the neutralization of the Japanese on New Guinea as far west as Wewak. In the same period, the Japanese loss of the Central Solomons and the Aleutians convinced Tokyo to convert New Guinea into a delaying action to keep as many of MacArthur's troops tied down as possible. Under these new strategic guidelines, the campaign continued.
Australian troops arrived at Finschhafen on 22 September, quickly cleared the port, then started up the Satelberg ridge line where they took heavy casualties against the entrenched defenders.
Two weeks later the Japanese retaliated with a ground attack, easily repulsed by the Australians, and an amphibious landing that was much harder to repel. The Japanese counterattack was eventually broken, and Finschhafen was occupied on 2 October, but the Japanese fought on until late November 1943, with a loss of at least 5,500 soldiers.
MacArthur's next New Guinea objective was Madang, about halfway between Finschhafen and Wewak. To strike Madang, Allied amphibious forces were protected on the flank from Japanese based on New Britain by the seizure of bases there. On 15 December, three Army landings were made in the Arawe area followed on 26 December by a larger landing of U.S. Marines which captured the important air base at Cape Gloucester.
During December 1943, Australian troops moved both from Finschhafen along the coast on the north side of Finisterre Range as well as through the Ramu Valley on the south side of the range. Saidor, 175 miles west of Finschhafen, was taken with an unopposed landing of U.S. Sixth Army troops on 2 January 1944 to cut off the Japanese retreat, trapping a division at Sio. The Japanese sidestepped inland around Saidor, abandoning equipment and valuable cryptographic intelligence materials retrieved by the Allies. Continuing air attacks against Japanese supply lines and airfields by Army and Naval forces contributed materially to the
success of ground operations.
Allied Forces Gain the Advantage in New Guinea
By 31 January 1944, MacArthur's SWPA forces had three regimental combat teams, three engineer special brigades, and five Australian infantry divisions, with three more U.S. infantry divisions on the way. Combat effectiveness was much higher as the lessons of jungle fighting were applied in training and support disciplines. As important, the Allies had achieved overwhelming numerical superiority in air and naval strength. The Japanese, in contrast, could not replace their losses in aircraft, shipping, and skilled manpower. However, they were helped by the New Guinea jungle that sheltered them from Allied planes and made large scale offensive maneuvers against them difficult or impossible.
MacArthur used Allied air and naval superiority to land troops where the Japanese were weakest, to confine the stronger Japanese forces to pockets from which they could not break out due to natural terrain obstacles and the Allied control of air and sea. The next nine months of 1944 were devoted to this strategy.
Capture of the Admiralties at the end of February 1944 isolated Rabaul and gave MacArthur a forward air base that extended his fighter range past Wewak. He took advantage of the superior position and battle resources by ordering a change in plans that would leapfrog 400 miles up the New Guinea coastline to capture the major Japanese air and supply base at Hollandia, in the Humboldt Bay area. Sixty B-24 heavy bombers, escorted by long-range P-38s, went against Hollandia on 30 March, demolishing nearly all the Japanese aircraft and ending any threat to the Allies from the sky over New Guinea. A well-designed deception effort kept the Japanese expecting a blow at the Madang-Hansa area while the true focus shifted to the west at Hollandia and Aitape, splitting the Japanese forces on New Guinea in half. On 22
April, three landings were made by the U.S. Sixth Army, two in the Hollandia area and one to the east at Aitape. On 26 April the pincers closed on Hollandia and the few surviving Japanese fled to the jungle in hopes of reaching Sarmi, about 150 miles to the northwest.
The next leapfrog landed unopposed in Maffin Bay near Sarmi on 17 May and took the small Wakde Island after two days of unexpectedly heavy fighting. An attempt on Sarmi Village (about eighteen miles west of the beachhead) was held up by an effective Japanese defense and threatened counterattack. Lone Tree Hill, the high ground dominating Maffin Bay, was finally taken by reinforcements on 24 June. Scattered resistance continued through the end of 1944; the fighting near Sarmi cost U.S. Army units approximately 2,100 battle casualties while over 10,000 Japanese perished.
Biak, Noemfoor, and Aitape
On 27 May, another leap of over 300 miles was made to seize airfields on Biak Island (dominating strategic Geelvink Bay) where fierce enemy resistance was encountered. The delay at Biak led to the order for the U.S. Sixth Army to seize Noemfoor Island (60 miles west of Biak) on 2 July and clear it of Japanese defenders to make its airstrips available for Allied operations. The advance continued to Sansapor on 30 July and to the island of Morotai on 15 September 1944.
While Biak and Noemfoor were secured, 500 miles to the east intelligence reports warned that the Japanese Eighteenth Army was approaching Aitape, held by the Allies since their 22 April landing. Engineers had converted the Aitape Japanese airdromes into a major fighter base, well defended by prepared positions close to the base and by a weak outer defensive perimeter along the western banks of the shallow Driniumor River, about fifteen miles east of the airstrips.
Rather than wait for an enemy blow to fall, on 10 July U.S. Army units moved out across the Driniumor and probed cautiously eastward, missing the Japanese force massed to attack in the opposite direction. That night ten thousand Japanese attacked across the Driniumor, charging through the center of the badly outnumbered defending force, precipitating a month-long battle of attrition in the New Guinea jungle. In the end, the Japanese were cut up and trapped between the Americans in the west and the Australians in the east, at Wewak. During July and August 1944, nearly 10,000 Japanese perished. Almost 3,000 Americans were casualties along the Driniumor, 440 of them killed, including four awarded posthumous Medals of Honor. It was MacArthur's most costly campaign since Buna.
As fighting along the Driniumor wound down, MacArthur's final assault landing on New Guinea took place at Sansapor, a weak point between two known Japanese strongholds on the Vogelkop Peninsula. About 15,000 Japanese troops were at Manokwari, 120 miles east of Sansapor, while sixty miles to Sansapor's west were 12,500 enemy soldiers at Sorong, a major air base complex. The well-tested amphibious leapfrog was used at Sansapor, with 7,300 men landing unopposed on 30 July 1944, splitting the Japanese. Two airfields were quickly built to provide support for the invasion of Morotai in the Molucca islands. Allied forces remained to defend the airfields, but the remaining Japanese were isolated and on the defensive. Major fighting in New Guinea was over as of 31 August 1944.
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