After the landing, the Australians began establishing a beachhead several kilometres deep, during which significant actions were fought around Siki Cove and Katika. Late in the day, a large Japanese air raid struck the Allied fleet off shore, but this was eventually defeated by a strong US fighter umbrella that was forewarned by Allied picket ships. The following day, 23 September, the 20th Brigade's drive on Finschhafen began, with two battalions commencing the advance south – the 2/13th and 2/15th supported by the 2/12th Field Regiment as well as engineers from the 2/3rd Field Company  – while the 2/17th was split up, with two companies advancing as part of the brigade's reserve, while another remained to secure the beachhead from a Japanese attack and push it further to the north, and the fourth pushed towards Sattelberg. The 2/3rd Pioneer Battalion remained in the beachhead, working to improve roads, while the 2/8th Field Ambulance set up a main dressing station, which would receive casualties as they were evacuated rearwards from the advanced dressing station that was following the battalions advancing south.
