After an amphibious landing at Nassau Bay, the Australians were reinforced by a US regimental combat team, which subsequently advanced north up the coast.

As the Allies kept up the pressure on the Japanese around Salamaua, in early September they launched an airborne assault on Nadzab, and a seaborne landing near Lae, subsequently taking the town with simultaneous drives from the east and north-west.

Salamaua was a staging post for attacks on Port Moresby, such as the Kokoda Track campaign, and a forward operating base for Japanese aviation.

[9] Following the conclusion of the fighting around Wau in late January, the Okabe Detachment had withdrawn towards Mubo, where they began to regroup, numbering about 800 strong.

[11] While the 2/7th made little progress, they provided a diversion for Major George Warfe's 2/3rd Independent Company, which advanced in an arc and raided Japanese positions at Bobdubi Ridge, inflicting severe losses.

[11] At the same time as the first battle at Mubo, the Australian 24th Infantry Battalion, which had been defending the Wampit Valley in an effort to prevent Japanese movement into the area from Bulolo,[12] detached several platoons to reinforce the 2/3rd Independent Company.

[14] In response to the Allied moves, the Japanese Eighteenth Army commander, Lieutenant General Hatazō Adachi, sent the 66th Infantry Regiment from Finschhafen to reinforce the Okabe Detachment and launch an offensive.

[17] At the same time as the second Australian assault on Bobdubi, on 30 June – 4 July, the US 162nd Regimental Combat Team (162nd RCT), supported by engineers from the 2nd Engineer Special Brigade,[9] made an unopposed amphibious landing at Nassau Bay and established a beachhead there,[18] to launch a drive along the coast, as well as bringing ashore heavy guns with which to reduce the Japanese positions.

[19] A week after the Bobdubi attack and Nassau Bay landing, the Australian 17th Brigade launched another assault on Japanese positions at Mubo.

Throughout late August and into early September the Japanese in the Salamaua region fought to hold the advancing Allies along their final line of defence in front of Salamaua, nevertheless the 58th/59th Infantry Battalion succeeded in crossing the Francisco River and the 42nd Infantry Battalion subsequently captured the main Japanese defensive position around Charlie Hill.

[3] Throughout the fighting, Allied aircraft and US PT boats supported the troops ashore, enforcing a blockade of the Huon Gulf and the Vitiaz and Dampier Straits.

[26] This was a classic pincer movement, involving an amphibious assault east of the town, and an airborne landing near Nadzab, 50 kilometres (30 mi) to the west.

The airborne forces secured Nadzab Airfield, so that the Australian 7th Division, under Major General George Vasey, could be flown in, to cut off any possible Japanese retreat into the Markham Valley.

The 7th Division suffered its worst casualties of the campaign on 7 September, as they were boarding planes at Port Moresby: a B-24 Liberator bomber crashed while taking off, hitting five trucks carrying members of the 2/33rd Infantry Battalion: 60 died and 92 were injured.

[32][33] On 11 September, the 7th Division's 25th Infantry Brigade engaged about 200 Japanese soldiers entrenched at Jensen's Plantation in a firefight, at a range of 50 yards (46 m),[34] with the 2/4th Field Regiment providing artillery support.

The Australian I Corps commander, Lieutenant General Sir Edmund Herring, visited Salamaua by PT boat on 14 September, three days after its capture, and found little more than bomb craters and corrugated iron.