In July 1942, the United States Joint Chiefs of Staff approved a series of operations (collectively called Operation Cartwheel) by General Douglas MacArthur, the Supreme Commander, South West Pacific Area (SWPA), against the Japanese bastion at Rabaul, which blocked any Allied advance along the northern coast of New Guinea toward the Philippines or north toward the main Japanese naval base at Truk.

In December that year, the Japanese began reinforcing Lae as they sought to shore up their southern flanks after the failure of operations to capture Port Moresby.

[8] Its strategic position, adjacent to the Solomon Sea, meant that it was the main Japanese base in the region,[9] and throughout 1943 plans were made to hold both Lae and Salamaua.

It had been developed as a port to meet the needs of the gold fields to the south, but there was no harbour, and deep water offshore meant that the anchorages were limited.

[15][16] The landing would be made by Major General George Wootten's 9th Division, veterans of the siege of Tobruk and the First and Second Battles of El Alamein.

[17] It had returned to Australia from the Middle East after El Alamein,[18] and been re-equipped, re-organised and re-trained for jungle operations around Kairi on the Atherton Tablelands in Queensland.

It was commanded by Rear Admiral Daniel E. Barbey, and operated large ocean-going landing ships such as the LST, LCI and LCT.

[34] Ammunition requirements were based on experience in the desert, there being no reliable data on usage in SWPA due to acute supply difficulties.

As the fifth wave of seven LCIs was coming in to Red Beach, they were attacked by six Zeke fighters and three Betty bombers that dropped twelve bombs.

The 2/17th Infantry Battalion came ashore on Red Beach behind the 2/15th, and pushed itself towards the west to force its way across the Buso River, and establish a beachhead on its opposite bank.

Tasked with advancing from the north-west, its main role was to act as a buffer between the 9th Division and Japanese reinforcements which might try to move down through the Markham and Ramu Valleys.

In response to the landing at Nadzab, the Japanese command ordered Lieutenant General Hidemitsu Nakano's 51st Division to reinforce Ryoichi Shoge's heavily entrenched garrison at Lae, falling back from the Salamaua region.

[61] Pushing their way across the Bunga and Buiem Rivers, the 2/23rd fanned out through Apo village while maintaining contact with the 2/17th Infantry Battalion by signal cable.

A platoon under Sergeant Don Lawrie was pushed forward near the mouth of the river as a protection measure to provide early warning.

Having been alerted by Lawrie's platoon who had sent back two runners, the battalion was able to repel the attack, although numerous casualties were inflicted on the 2/23rd and the 2/17th by Japanese mortars.

These were fended off over the course of the afternoon, and by evening, as heavy rain began to fall, the Australian platoon was able to break contact and withdraw back to the 2/23rd's main defensive position.

[61] The Japanese assault on the 2/23rd subsequently delayed the 9th Division's advance for several days, and these would eventually prove significant as in that time, the rain set in,[61] flooding the numerous waterways that forked inland from the coast.

The going was slow, with the ground saturated, and the thick jungle and kunai grass along the route of advance delayed the troops who had to cut several tracks through the foliage.

[63] By 8 September, the commander of the Japanese 51st Division, Nakano, gave the order for his forces and those in Lae to begin their withdrawal northwards, as it became clear that the twin drives on the town threatened them with encirclement.

Norman then shifted his focus to the mouth of the river, where there was a small central island that could be exploited to provide some cover for the assaulting troops.

Covered by mortars and heavy machine guns, the Western Australians fixed bayonets and advanced in company lots, with the men strung out in extended line.

On 10 September, the commandos providing flank security managed to get across the Sankwep River, close to its confluence with the Busu, pushing a kunda bridge across.

The 2/7th Field Company was pushing a jeep track forward with the help of the 2/48th, and they subsequently arrived with boats, ropes and cables, and several attempts were made to get across, all of which eventually failed as the engineers came under fire from the opposite bank.

[70] In addition to the weather, the Allied supply situation also proved problematic, with the geography making resupply efforts difficult, while service politics led to arguments between military and naval commanders developing over misunderstandings about the capabilities of the navy and the risks involved in operating close to the shore.

These factors combined to stymie the 9th Division's progress and as a result, the 7th Division's troops eventually beat the 9th in reaching the town, with its 25th Infantry Brigade – having fought a sharp action around Jensen's and Heath's Plantations – entering Lae on the morning of 16 September, just ahead of the 24th Infantry Brigade, which had taken the airfield around Malahang the day before.

He handed over responsibility for the town to US Brigadier General Carl W. Connell, the commander of US Base E. The advance party of Lieutenant Colonel O.

[74][75] The closure of the Markham Valley Road on 7 October due to heavy rainfall meant that the airbases at Nadzab and Gusap had to be maintained by air.

A total of about 9,000 Japanese troops subsequently began withdrawing across the Busu River and then through the Saruwaged and Finisterre Ranges to the north-east coast, while efforts were made to reinforce the Huon Peninsula, with the 20th Division being transferred from Madang to Finschhafen.

[81] The Allies subsequently launched a follow-up campaign on the Huon Peninsula, with a landing at Scarlet Beach by the 20th Infantry Brigade.

[84] This feat was described by the Kalgoorlie Miner as the "greatest march" of the New Guinea campaign and in 10 days the battalion covered 50 miles (80 km) of rugged terrain.