The 'Campaign for Salamaua and Lae' was a series of undertakings between Allied (primarily Australian) and Japanese forces for the area round the Huon Gulf in north-eastern New Guinea (22 April/16 September 1943).

In this campaign, Australian and US forces sought to capture two major Japanese bases, one in the town of Lae and the other in the town of Salamaua. The Japanese had taken these two places in 'Sr' (ii), and the Allied campaign to take the Salamaua and Lae area began after the successful defence of Wau late in January 1943, after which Australian forces advanced towards Mubo as the Japanese troops that had attacked Wau withdrew to positions around Mubo on the track liking Wau and Salamaua. A series of actions followed over the course of several months as Major General Stanley G. Savige’s Australian 3^rd Division advanced to the north-east in the direction of Salamaua. After an amphibious landing at Nassau Bay on 30 June 1943, the Australians were reinforced by a US regimental combat team, which then advanced to the north along the coast.

As the Allies maintained the pressure on the Japanese around Salamaua, early in September they launched an airborne assault on Nadzab up the Markham river from Lae, and a seaborne landing near Lae, subsequently taking the town with simultaneous drives from the east and north-west. As the situation around Lae grew more desperate, the Salamaua garrison withdrew, and the town was captured on 11 September 1943, while Lae fell shortly after this on 16 September, bringing the campaign to an end.

In March 1942, the Japanese secured Salamaua and Lae in 'Sr' (ii), and subsequently established major bases on the north-eastern coast of New Guinea in the large town of Lae and in Salamaua, which was a small administrative town and port 22 miles (35 km) to the south. Salamaua was a staging post for attacks on Port Moresby, such as the 'Campaign for the Kokoda Track', and a forward operating base for Japanese air power. When the attacks failed, the Japanese turned the port into a major supply base. Logistical considerations meant that the area of Salamaua and Lae area could accommodate a garrison of only some 10,000 Japanese personnel, in the form of 2,500 men of the Imperial Japanese navy and 7,500 men of the Imperial Japanese army. The defence of the area was based on Major General Toru Okabe’s 'Okabe' Detachment, a brigade-sized force from Lieutenant General Hidemitsu Nakano’s 51^st Division, itself an element of Lieutenant General Hatazo Adachi’s 18^th Army.

In January 1943, the 'Okabe' Detachment was defeated as it attacked the Australian base at Wau, about 25 miles (40 km) to the south-west of Salamaua. Allied commanders then turned their attention to Salamaua, which could be attacked by troops flown into Wau. This also diverted attention from Lae, which was a major objective of the 'Cartwheel' Allied grand strategy for the South Pacific. It was decided that the Japanese would be pursued toward Salamaua by the Australian 3^rd Division, which had been formed at Wau, and there link with Savige, whose formation was to link with elements of Major General Horace H. Fuller’s US 41^st Division.

Following the end of the fighting around Wau late in January, the 'Okabe' Detachment had withdrawn toward Mubo, where it began to regroup as a force of about 800 men. Between 22 April and 29 May 1943, the Australian 2/7^th Battalion, at the end of a long and tenuous supply line, attacked the southern extremity of Japanese lines in the Mubo area, at features known to the Allies as 'The Pimple' and 'Green Hill'. While the 2/7^th Battalion made only little progress, it provided a diversion for Major George Warfe’s 2/3^rd Independent Company, which advanced in an arc and raided Japanese positions at Bobdubi Ridge, inflicting severe losses. In May, the 2/7^th Battalion repelled a number of strong Japanese counterattacks.

At the same time as the first battle at Mubo, the Australian 24^th Battalion, which had been defending the Wampit river valley in an effort to prevent Japanese movement into the area from Bulolo, detached several platoons to reinforce the 2/3^rd Independent Company. During May, these Australian forces were heavily engaged in patrolling the 3^rd Division’s northern flank, around the Markham river and the area around Missim, and one patrol reached the mouth of the Bituang river, to the north of Salamaua.

In response to these Allied moves, Adachi sent the 66^th Regiment from Finschhafen to reinforce the 'Okabe' Detachment and launch an offensive. Some 1,500 men strong, the 66^th Regiment attacked at Lababia Ridge, on 20.23 June in a battle which has been described as one of the Australian army’s classic engagements of World War II. The ridge’s only defenders were the men of the 2/6^th Battalion’s D Company, who had well-established and linked defensive positions, featuring extensive, cleared free-fire zones. These assets and the determination of D Company defeated the Japanese envelopment tactics.

Between 30 June and 19 August, Brigadier H. H. Hammer’s Australian 15^th Brigade cleared Bobdubi Ridge. The operation was opened with an assault by the inexperienced 58^th/59^th Battalion, and included hand-to-hand combat. At the same time as the second Australian assault on Bobdubi, between 30 June and 4 July, the US 162^nd Regimental Combat Team, supported by engineers of Brigadier William F. Heavey’s 2^nd Engineer Special Brigade, made an unopposed amphibious landing at Nassau Bay and established a beach-head, from which to launch a drive along the coast and allow the landing of heavy guns with which to reduce the Japanese positions.

A week after the Bobdubi attack and Nassau Bay landing, Brigadier M. J. Moten’s Australian 17^th Brigade launched another assault on Japanese positions at Mubo. With the Allies making ground closer to Salamaua, the Japanese withdrew to avoid encirclement, and Nakano, the Japanese divisional commander, then decided to concentrate his forces around Komiatum, which was an area of high ground to the south of Salamaua.

Meanwhile, the main body of the 162^nd Regimental Combat Team followed a flanking route along the coast before encountering fierce resistance at Roosevelt Ridge, so named for its commander, Lieutenant Colonel Archibald Roosevelt, between 21 July and 14 August. Between 16 July and 19 August, the 42^nd Battalion and 2/5^th Battalion gained a foothold on Mt Tambu, which they held in the face of fierce Japanese counterattacks. The battle turned when they received assistance from the 162^nd Regimental Combat Team. Throughout July, the Japanese sought to reinforce the Salamaua area, drawing troops away from Lae, and by the end of the month there were around 8,000 Japanese troops around Salamaua.

On 23 August, Savige and the 3^rd Division handed over the Salamaua operation to the Australian 5^th Division under the command of Major General E. J. Milford. Throughout the period between late August and early September, the Japanese in the Salamaua region fought to hold the advancing Allies along their final line of defence in front of Salamaua, but the 58^th/59^th Battalion succeeded in crossing the Francisco river and the 42^nd Battalion subsequently captured the main Japanese defensive position around 'Charlie Hill'.

After Allied landings near Lae in the first week of September, Adachi, the 18^th Army's commander, ordered Nakano to abandon Salamaua, and subsequently Nakano’s forces withdrew to the north and transferring between 5,000 and 6,000 troops by barge, while other troops marched out along the coastal road. The 5^th Division subsequently occupied Salamaua on 11 September, securing its airfield.

The fighting between April and September in the Salamaua region cost the Australians 1,083 casualties, including 343 dead. The Japanese lost 2,722 men killed and a further 5,378 wounded, for a total of 8,100 casualties. The US 162^nd Regimental Combat Team lost 81 men killed and 396 wounded. Throughout the fighting, Allied aircraft and US PT-boats supported the troops ashore, enforcing a blockade of the Huon Gulf and the Vitiaz and Dampier Straits.

The main operation to take Lae was 'Postern'. Schemed as part of wider-ranging operations eventually to secure the Huon peninsula, the capture of Lae was planned by General Sir Thomas Blamey, commander of the Allied New Guinea Force, and Lieutenant General Sir Edmund Herring, the commander of the Australian I Corps. This was a classic pincer movement, involving an amphibious assault to the east of the town and an airborne landing near Nadzab, 32 miles (50 km) to its west. Battle casualties for the 9^th Division during 'Postern' amounted to 547 men, of whom 115 were killed, 73 posted as missing and 397 wounded, while the 7^th Division suffered 142 casualties, of which 38 were killed. The Japanese lost about 1,500 killed, while a further 2,000 were taken prisoner.

On 4 September, the Australian 9^th Division, under Major General G. F. Wootten, landed to the east of Lae on 'Red' beach and 'Yellow' beach, near Malahang at the start of an attempt to encircle the Japanese forces in the town. Five US Navy destroyers provided gunfire support. The landings were not opposed by land forces but were attacked by Japanese bombers, which inflicted numerous casualties among the naval and military personnel on board several landing craft.

Brigadier W. J. V. Windeyer’s 20^th Brigade led the assault, with Brigadier D. A. Whitehead’s 26^th Brigade following and Brigadier S. H. W. C. Porter’s 24^th Brigade constituting the divisional reserve. The 9^th Division faced formidable natural barriers in the form of rivers swollen by recent rain, and was brought to a halt on the Busu river, which could not be bridged as the 9^th Division lacked the necessary heavy equipment, and the far bank was occupied by the Japanese. On 9 September, the 2/28^th Battalion led the attack across the Busu river and secured a bridgehead after fierce fighting.

On the following day, the US 503^rd Parachute Infantry, together with two gun crews of the Australian 2/4^th Field Regiment, who had received a crash course in the use of parachutes, and their cut-down 25-pdr gun/howitzers, made an unopposed airborne drop at Nadzab, just to the west of Lae. The airborne forces secured Nadzab airfield, so that the Australian 7^th Division, under the command of Major General G. A. Vasey, could be delivered by air to cut off any possible Japanese retreat into the Markham river valley. The 7^th Division suffered its worst casualties of the campaign on 7 September, as its men were boarding aircraft at Port Moresby: a Consolidated B-24 Liberator four-engined heavy bomber crashed while taking off, hitting five trucks carrying members of the 2/33^rd Battalion, of whom 60 were killed and 92 injured.

On 11 September, the 7^th Division’s 25^th Brigade, commanded by Brigadier K. W. Eather, engaged about 200 Japanese soldiers entrenched at Jensen’s Plantation in a firefight at a range of 50 yards (45 m), with the 2/4^th Field Regiment providing artillery support. After defeating them and killing 33 Japanese soldiers, the brigade engaged and defeated a larger Japanese force at Heath’s Plantation, killing 312 Japanese soldiers. The 25^th Brigade entered Lae on 15 September, just before the 9^th Division’s 24^th Brigade, and the two formations linked on that day.

While the capture of Lae was clearly a victory for the Allies, and achieved more quickly and at lower cost than had been anticipated, a significant proportion of the Japanese garrison had escaped through the Saruwaged mountain range, to the north of Lae, and would have to be fought again in the 'Campaign for the Huon Peninsula', and a quick follow-up undertaking was the 'Diminish' landing on 'Scarlet' Beach by the 20^th Brigade.

Despite initial plans to do so, Salamaua was not developed as a base. Herring, the commander of the Australian I Corps, visited Salamaua by PT-boat on 14 September, three days after its capture, and found little more than bomb craters and corrugated iron. He recommended cancelling the development of Salamaua and concentrating all available resources on Lae. The base that had originally been envisaged now seemed a waste of effort as Salamaua was a poor site for a port or air base. However, in drawing the Japanese attention away from Lae at a critical time, the assault on Salamaua had already served its purpose. Lae, on the other hand, was subsequently transformed into two bases: the Australian Lae Base Sub Area and the USASOS Base E. Herring combined the two as the Lae Fortress, under Milford’s command. As Blamey had launched 'Postern' before the logistical preparations were complete, most of the units needed to operate the base were not yet available.

The importance of Lae as a port was to supply the air base at Nadzab, but this was compromised because the Markham river valley road was found to be in poor condition. To expedite the development of Nadzab, minimal efforts were made to repair it, and heavy military traffic bound for Nadzab was permitted to use it. The road was closed following heavy rains on 7 October and did not reopen until December. Until then, Nadzab had to be supplied by air, and its development was slow because heavy engineer units could not get through.