Following the success of the Salamaua raid, Captain Winning's small force knew that it could expect some sort of response from the Japanese command. It was not long in coming. Enemy aircraft bombed Wau, Bulolo and Skindiwai on 2 July, and again on the following day. During the Bulolo attack, the 2/5th Independent Company quartermaster, Staff Sergeant Mal McCallum, and his assistant, Corporal Archie Crellin, were killed and the stores damaged. In the Wau attack, some houses were destroyed and a number of natives wounded, while the majority of the native carriers went bush.

On 3 July Captain Winning sent a message to Colonel Fleay, setting out the strength of his force at Mubo, which was just 49 men spread over four sections. Despite the attached NGVR men, it was hardly a force to contest any serious Japanese move on Mubo and Wau. Nonetheless, daily patrols were sent out from Mubo to the Francisco River to check on any enemy moves.

On 10 July Captains Winning and Umphelby, the latter very ill, arrived in Wau and told Colonel Fleay of the poor condition of their troops. Lieutenant Richard De Meyrick's 1 Section was sent forward to Mubo as reinforcements, with Lieutenant Bill Ridley's 6 Section following them on 19 July. Meanwhile, the Japanese garrison in Salamaua had been receiving more significant reinforcements.