On 23 January 1942, Japanese forces under Major General Horii Tomitaro invaded New Britain, capturing Rabaul from its Australian garrison, known as Lark Force. Moving into mainland New Guinea on 8 March, Japanese forces then occupied Lae and Salamaua. The Australian defenders (code-named Kanga Force) retreated to the mountain town of Wau while the Japanese moved against the ports of Madang, Finschhafen, and Wewak. For the next 10 months, there was a stalemate as both sides poured resources into the Papuan Campaign.
When the Papuan Campaign ended on 25 January 1943, 1,000 Japanese survivors escaped into New Guinea. That month the Japanese dispatched to New Guinea Lieutenant General Adachi Hatazo's Eighteenth Army. This included the 6th Air Division. The Japanese 41st Division deployed to Wewak, the 20th Division deployed to Madang, and part of the 51st Division was dispatched to Lae/Salamaua.
To oppose the Japanese, General Douglas MacArthur had the U.S. 32nd and 41st Divisions and the Australian 6th and 7th Divisions and a militia brigade. The 32nd Division was not immediately available as a consequence of battle losses, and two of the brigades of the Australian 7th Division were temporarily deployed to Ceylon. The remaining brigade was sent to New Guinea to reinforce the militia brigade there. Australia was raising more militia, and its veteran 9th Division returned from Egypt in February. MacArthur also had the U.S. Fifth Fleet as well as the Royal Australian Air Force and the small U.S. Seventh Fleet comprising U.S., Australian, and Dutch warships.
To recover the initiative, Adachi ordered his 102nd Regiment to attack Wau on 16 January. By 28 January, the Japanese had driven Kanga Force to the edge of Wau Airfield, but the Australian 17th Brigade then flew in under Japanese fire to reinforce Wau. The fighting lasted until 30 January, when the Japanese retreated to Salamaua. This defeat depleted the Japanese forces available to defend Lae/Salamaua. Thus on 28 February, the bulk of the Japanese 51st Division boarded 8 merchantmen at Rabaul and, escorted by 8 destroyers, this force sailed for Lae.
On 1 March, Allied aircraft spotted this convoy in the Bismarck Sea. MacArthur's air commander, Lieutenant General George Kenney, attacked with 181 aircraft. Employing skip-bombing techniques, during 2–5 March Kenney's planes destroyed all 8 Japanese transports and 4 destroyers, resulting in the loss of some 3,700 men. Only 850 Japanese soldiers reached Lae. In retaliation, the Japanese launched I Operation to destroy Allied air power in Papua and Guadalcanal. Between 11 and 14 April, Japanese aircraft struck Oro Bay, Milne Bay, and Port Moresby, destroying 2 Dutch merchantmen and 45 Allied planes. But Japanese aircraft losses were higher.
Both sides now slowly built up their forces. The Japanese used barges and submarines to reinforce Lae/Salamaua. MacArthur flew troops into Wau. During April, the Australian 3rd Division assembled at Wau and began to push toward Salamaua. MacArthur needed a coastal base for his twin offensives against Lae and Salamaua, and in the Seventh Fleet's first amphibious operation, the U.S. MacKechnie Force (named for Colonel Archibald R. MacKechnie) seized Nassau Bay on 29 June 1943. The Americans then moved up the coast toward Salamaua, linking up with the Australians on 21 July. Distracted by this threat, the Japanese were surprised by a U.S. airborne drop on Nazab in the Markham Valley on 1 September. Allied forces quickly constructed airfields to receive the 7th Division, which began an inland advance on Lae. The 9th Division then landed north of Lae on 4 September. The encircled Japanese abandoned Salamaua on 17 September and Lae the next day and retreated into the interior.
Pursued by the 7th Division, the Japanese conducted a fighting withdrawal through the rugged terrain of the Markham and Ramu Valleys. It took the Australians a month to overcome a key Japanese position at Sattleberg. To prevent these Japanese from reaching Finschhafen on the coast, the Australian 20th Brigade landed farther west at Scarlet Beach on 22 September. Now isolated, the defenders of Finschhafen joined the Japanese exodus inland on 2 October. Adachi tried to retake Finschhafen by counterattacking Scarlett Beach on 20 October, but his forces were defeated. MacArthur had found a winning strategy. He used the Australians to engage the Japanese while his American forces bypassed Japanese strongholds.
On 23 December 1943, U.S. Marines invaded New Britain Island. The Allies then constructed air bases there, enabling them to neutralize Japanese aircraft from Rabaul. On 2 January 1944, the U.S. 126th Regiment invaded Saidor and began a coastal drive on Madang. Meanwhile, the Australians pursued the Japanese overland toward Bogadjim, where a supply road led to Madang. Japanese defenses that were centered around Shaggy Ridge were taken on 23 January.
On 29 February 1944, U.S. forces invaded the Admiralty Islands north of New Guinea, severing the Japanese Eighteenth Army's lifeline to Rabaul. Then, on 10 February, the Australians linked up with the Americans at Saidor. The Japanese High Command reacted to this by withdrawing their defense line to Wewak, supported by a new base at Hollandia in Dutch New Guinea. The Japanese then sent their 6th Air Division from the Netherlands East Indies to defend these bases. Radio intercepts revealed these plans to MacArthur, who ordered an air offensive against Wewak and Hollandia. From 30 March to 16 April, the Fifth Air Force obliterated the 6th Air Division, destroying 390 planes and killing 2,000 Japanese pilots and air personnel.
After the fall of Bogadjim on 17 April 1944, the road to Madang was open to the Allies. Adachi evacuated his Madang headquarters, intending to fall back on Wewak and Hollandia. On 24 April, the Australians entered Madang. Two days previously, U.S. forces had invaded Hollandia and Aitape. The Allied capture of Aitape 125 miles east of Hollandia blocked the escape of the Eighteenth Army. Now desperate, Adachi used his dwindling resources to transport three regiments to Aitape. Their unexpected attack on 11 July drove the U.S. 32nd Division to the Driniumor River. Fighting continued until 25 August, when the Japanese retired to Wewak.
During October 1944, the Australians replaced the Americans at Aitape. MacArthur's return to the Philippines was to be an American operation, with the Australians consigned to containing the bypassed Japanese. But the Australian government wanted Wewak retaken. This pointless offensive had little air or naval support, as that support had gone to the Philippines. On 23 May 1945, Wewak fell to the Australians, and Adachi retreated into the Prince Alexander Range for a last stand. The remnants of the Eighteenth Army surrendered there on 13 September 1945. Jonathan "Jack" Ford
Bergerud, Eric. Touched with Fire: The Land War in the South Pacific. New York: Viking, 1996.; Dexter, David. Australia in the War of 1939–1945. Series I (Army), Vol. 6, The New Guinea Offensives. Canberra: Australian War Memorial, 1961.; Long, Gavin. Australia in the War of 1939–1945. Series I (Army), Vol. 7, The Final Campaigns. Canberra: Australian War Memorial, 1963.; Miller, John, Jr. The United States Army in World War II: The War in the Pacific: Cartwheel: The Reduction of Rabaul. Washington, DC: Center of Military History, U.S. Army, 1993.; Smith, Robert Ross. The United States Army in World War II: The War in the Pacific: The Approach to the Philippines. Washington, DC: Office of the Chief of Military History, 1953.
Jonathan "Jack" Ford