Following the capture of Lae by the 7th and 9th Australian Divisions in early September 1943, the 7th Division was ordered into the mountains to pursue Japanese forces across the Finisterre Range. The 9th Division was ordered to take the Huon Peninsula: its objectives included Japanese strongpoints at Finschhafen and Sattelberg.
This was to be the 9th Division's first full campaign in New Guinea. Lauded as 'The Rats of Tobruk' for the division's exploits there in 1941, the 9th Division had stayed in the Middle East when other troops returned to Australia in 1942, and had fought in the First and Second Battles of El Alamein between June and November 1942.
The 9th Division had returned home in early 1943 to a heroes' welcomes. Under the command of their newly appointed divisional commander, Major-General George Wootten, the men started their jungle warfare training for the campaigns that lay ahead. Wootten, who had recently commanded the 18th Infantry Brigade at Milne Bay, Buna and Sanananda in Papua in 1942, had been a Rat of Tobruk, when the 18th Brigade served alongside the three brigades of the 9th Division during the siege.
The campaign began with the militia 22nd Infantry Battalion, which set out along the coast from Lae, on foot, towards Finschhafen. The men had to cross many rivers, moving cautiously, in case of ambush. Papuan troops acted as guides, and helped track down Japanese troops who had escaped from Lae, although most of the garrison had escaped into the mountains.
The main landing by the 9th Division was made at Scarlet Beach, a few kilometres north of Finschhafen, on 22 September 1943. The 20th Brigade stormed ashore, from American landing craft and started their advance. (The landing craft had fortuitously missed the allocated landing beach and so avoided heavy Australian losses from Japanese coastal defences placed at the original landing spot.) Unlike in the earlier campaigns when many Japanese had fought to the death, refusing to retreat, the Japanese now ordered withdrawals, preserving men for future battles.
As most of the 20th Brigade advanced on Finschhafen, which was captured after 11 days, with some hard fighting, other troops started advancing inland. They were ordered to take the imposing Sattelberg Mountain, which was the dominant feature in this area, and therefore needed to be captured. More troops of the 9th Division had arrived on 10-11 October to take over this advance, but at about the same time the Japanese 20th Division launched a counter-attack. The Australians faced hard fighting around Sattelberg and Jivevenang, while back on the coast a small landing by Japanese troops was defeated by Australian and American base troops. It was almost the end of November before the Australians were able to capture Sattelberg – with, famously, a last dashing charge by Sergeant Tom 'Diver' Derrick, 2/48th Battalion, who took the actual mountaintop single-handedly, an action for which he was awarded the Victoria Cross.
The 9th Division advanced on, with the 24th and 26th Brigades, joined by the militia 4th Brigade, securing the Wareo and Gusika areas, encountering stiff opposition. By mid-December 1943, the remnants of the Japanese 20th Division were retreating up the coast to Sio, pursued by the Australians. The Japanese had to leave behind many sick and wounded, some of whom managed to fight on, and slow the Australian advance.
On 15 January 1944, the 9th Division captured Sio. It marked the end of this first jungle campaign for the Rats of Tobruk. The division had lost more than 1000 men killed, and was exhausted.
The advance beyond Sio was taken over by the 8th Infantry Brigade, another militia formation, which pursued the retreating Japanese to Madang. The Australians entered Madang on 24 April 1944, unopposed, after the enemy had continued retreating.