Finschhafen region from around late July 1943, having appreciated its significance in relation to the Vitiaz and Dampier Straits. The Japanese Eighteenth Army commander, Lieutenant General Hatazo Adachi, had begun moving forces into the region. The majority of these were drawn from the 20th Division, which dispatched a force of about 2,800 men from Madang in August. These forces consisted of the 80th Infantry Regiment, one battalion of the 26th Field Artillery Regiment, and the 7th Naval Base Force. In addition, following the fall of Lae, elements of the 41st Division – primarily the 238th Infantry Regiment – and the 51st Division's 102nd Infantry Regiment, were also moved to the area, and were placed under the command of Major General Eizo Yamada, commander of the 1st Shipping Group. The total number of Japanese in the area was around 4,000 to 5,000, although Allied intelligence estimated a strength of between 350 and 2,100. Yamada's forces were spread out in a series of outposts that were orientated around a main defensive position established at Sattelberg, an abandoned Lutheran mission situated atop a mountain that dominated the terrain about north-west of Finschhafen. The Japanese forces lacked transportation and the road network had not been fully developed. They were low on ammunition for all calibres of weapons, especially artillery, and the majority of stores had to be carried by combat troops, as local carriers had ceased working for the Japanese in response to Allied propaganda. Following the landing at Scarlet Beach, Yamada was ordered to launch an attack on the Australian forces in order to delay them so that further reinforcements could arrive from the 20th Division. Battle Australian drive on Finschhafen 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