This sealed the Japanese decision to quit the Sio area, and over the course of two weeks the Australians advanced swiftly up the coast, overcoming only "sporadic opposition" as the Japanese continued to withdraw to the west towards Madang, seeking to avoid being cut off by the forces at Saidor. The 2/15th took over the advance on 31 December, reaching Nunzen on New Years Day. The Sanga River was crossed on 2 January 1944 and the following day the 2/17th reached Cape King William. Further river crossings followed at the Sazomu and Mangu Rivers as Kelanoa fell on 6 January; next, the Dallman and Buri Rivers were forded as Scharnhorst Point was rounded on 9 January. After a final action was fought at Nambariwa, the 2/17th finally reached Sio on 15 January.