At the beginning of the Second World War, Wau, in the Buolo Valley in New Guinea (present-day Papua New Guinea) was a small mining settlement. The Wau area was the scene of a great deal of fighting in 1942-43 because the town stood astride a route from the Japanese bases established at Lae and Salamaua in March 1942, to the Australian base at Port Moresby. From March until August 1942 Australian guerrilla troops, code named Kanga Force, operated along the tracks between Wau and Salamaua, but a Japanese drive to occupy Mubo, 30 km from Wau as the crow flies, caused them to withdraw behind Wau and set the town alight. The Japanese, however, had no intention at this stage of advancing beyond Mubo, which was to be fortified as a forward outpost to defend Salamaua. Guerilla operations continued around Wau and, with the Japanese inactive at Mubo, Wau was reoccupied and infrastructure restored.
In January 1943, the 17th Brigade began to arrive at Wau by air to reinforce Kanga Force and to ensure the security of the Buolo Valley as a base for future operations. At the same time, as a result of their defeat along the Kokoda Trail, the Japanese commenced operations to prevent this. Japanese movement towards Wau was first detected on 21 January and several companies of the 2/6th Battalion were deployed east of the town to block their approach. The first contact with the attacking force occurred on 28 January but, despite reinforcement, the Australians were not strong enough to impede the Japanese. That night the Japanese moved within 3 km of Wau, then defended by little more than two companies from the 2/5th Battalion. Over the next two days reinforcements, consisting of the rest of the 2/5th and all of the 2/7th, were flown into Wau airfield. With the airfield under fire, the troops went straight into action upon leaving their planes. The main Japanese attack fell upon Wau before dawn on 30 January. Dogged resistance by the Australians robbed the Japanese of their momentum and the 2/7th launched a counter-attack late in the afternoon. This attack effectively marked the turning point of the battle for Wau. In ensuing days, as reinforcements continued to fly in, the Australian forces began a series of attacks to edge forward of their defensive positions at Wau. By 6 February the Japanese were retreating towards Mubo. Follow-up operations commenced immediately, but Mubo would not be back in Australian hands until July.