After flanking moves failed in early July, Australian efforts to secure Mubo were renewed and the Japanese were finally forced to withdraw from the area towards Mount Tambu in mid-July.

[3][4] In late January 1943, in the wake of their defeat around Buna and Gona, the Japanese had sought to shore up their hold of Lae by capturing Wau and establishing a perimeter.

[7] Following them up, the Australian force – consisting mainly of the 17th Brigade under the command of Brigadier Murray Moten – had advanced into the area surrounding Wau and had begun moving towards Mubo.

[12] In an effort to defend the approaches to Wau, troops from the 2/7th Infantry established one company in a defensive position around Lababia Ridge, which was located about 2 kilometres (1.2 mi) south-west of Mubo;[13] other companies were established at Waipali, as well as Mat Mat Hill – on the opposite bank of the Bitoi River – and further to the south around Hill 7.

The Australians had been slowly trying to gain the initiative by patrolling, and in late April Moten decided to launch an attack on two features of high ground in front of their position: the Pimple and Green Hill.

The initial assault went in on 24 April, following air attacks by Douglas A-20 Boston aircraft, which proved ineffective in softening up the target area.

Under the command of Captain Leslie Tatterson, the Australian company fought a desperate defensive action as they were isolated and heavily assaulted.

Over the course of several days, about 500 Japanese troops from the 102nd and 115th Infantry Regiments – part of Hidemitsu Nakano's 51st Division – launched eight attacks on the position, until finally a group of 60 reinforcements were able to break through to them on 11 May.

Following the initial assault on the Australian company, the Japanese had brought in reinforcements and now numbered about 600 men, which were mainly drawn from the 66th Infantry Regiment.

Attacks around Bobdubi and Nassau Bay allowed US and Australian forces to link up, while the 1st Battalion, 162nd Infantry Regiment, under Lieutenant Colonel Harold Taylor, having just landed at Nassau Bay, was tasked with occupying the Bitoi Ridge on 5 July, in an effort to force the Japanese to withdraw from Mubo through indirect means.

The US soldiers were delayed in moving inland following the landing, and although the battalion's lead company subsequently succeeded in securing the southern part of the ridge, and had occupied the crest, nevertheless, the Japanese force remained around Mubo.

[29] Thus, further actions were fought throughout July and August around Roosevelt Ridge, Komiatum and Mount Tambu,[30] prior to the final capture of Salamaua on 11 September following advances by the Australian 15th and 29th Brigades, and the US 162nd Infantry Regiment.