Lababia Ridge was a high, steep, jungle-covered feature that rose out of the Bitoi River valley to the east of Mubo. It was crossed by several tracks that made it a key tactical position during the fighting around Mubo in mid-1943. One of these was the Jap Track, cut by Japanese troops for their attack on Wau earlier in the year, which ran north from the ridge to join the main Mubo-Salamaua Track. The other was the Lababia Track, which ran east along the ridge, paralleling the course of the Bitoi river, to the coast at Nassau Bay. Patrolling forward from Wau, the 2/7th Battalion occupied Lababia Ridge on 15 March 1943, and it became the site of a defensive position from which patrols were mounted along both the Lababia and Jap tracks. Progress along the Jap Track was blocked by strong Japanese positions on hills known as the Pimple and Green Hill; the most forward Australian position was sited 400 metres south of the Pimple.
The 2/7th Battalion mounted attacks on the Pimple on 24 April, and again on 2 and 7 May, but as these were poorly supported, and were all made from roughly the same direction, they could not destroy the well-sited position. On 9 May the Japanese made an attack of their own and encircled A Company of the 2/7th, which was holding the position just south of the Pimple. The Australians held their ground, but were cut off until a relieving force managed to break through on 11 May. Action around Lababia Ridge was confined to patrol clashes until the Japanese mounted another attack from the Pimple on 20 June. By this time the 2/7th Battalion had been withdrawn to rest and Lababia Ridge was occupied by D Company of the 2/6th Battalion. The forward post at the foot of the Pimple had been withdrawn and the Australian position consolidated approximately a kilometre further to the south. The battle lasted for four days. The Japanese first attempted to attack the position frontally, from the north, and then tried to outflank it - first from the east, then from the west. They were never able to complete encircle the position, however, which allowed reinforcements, supplies and ammunition to be brought forward, and the Australians held firm. Japanese resolve was finally destroyed by a strafing run by RAAF Beaufighters on the morning of 23 June. The 2/6th Battalion continued patrolling around Lababia Ridge in the weeks that followed and on 12 July both the Pimple and Green Hill were found to have been abandoned by the enemy.