Only four kilometres off the coast of New Guinea, in sight of the port of Wewak, Muschu is a flat, jungle covered island. Captured by the Japanese in 1942, it then became a food growing and collection area supplying the Wewak garrison. Early in its occupation the Japanese heavily fortified the island, including the installation of two 140mm naval guns capable of commanding the sea approaches to Wewak and also firing inland to support Wewak's defences.
By March 1945, the Japanese were being isolated by the advancing Australians who were preparing for the final major campaign of the war in New Guinea - the capture of the port of Wewak.
One problem facing the planners of the operation was the status of the defences on Muschu. Although the island could be easily isolated, intelligence information indicated increasing activity there, including the possibility that the naval guns, until recently believed to be inactive, had now been brought back into service. If this was true, it meant the guns could inflict heavy casualties on the Australians during the landings.
To determine the actual condition of Muschu's defences and the position of the naval guns, HQ Six Division decided to insert a Z Special Force reconaissance patrol onto the island.