The Landing at Nassau Bay was an amphibious landing by Allied forces at Nassau Bay during the New Guinea campaign of World War II that took place between 30 June and 6 July 1943. The operation was undertaken so that Allies could secure a beachhead to establish a supply point to shorten their supply lines for the proposed attack on Salamaua as part of the Salamaua–Lae campaign and resulted in a battalion-sized force of US infantry and supporting elements being landed largely unopposed on the south-eastern flank of the battle zone.
Due to bad weather, the landing force suffered heavy equipment losses with most of the US landing craft being wrecked in heavy seas. Nevertheless, the US troops were able to secure a lodgement from where they subsequently broke out, advancing north as part of a flanking drive on Salamaua, which was launched in conjunction with attacks by Australian forces further west. Australian forces also provided support during the landing, marking the landing beaches, and providing diversionary attacks against nearby Japanese forces. The landing was subsequently exploited with two more US infantry battalions being landed throughout early July, along with Australian and US artillery batteries, which were used to help reduce the Japanese positions around the Salamaua battle zone in the following months as the Allies sought to draw Japanese reinforcements away from Lae.
Background
In late June and early July, Allied forces were advancing towards Salamaua, having secured the airfield at Wau earlier in the year. Up to that point, the Australian forces that were fighting around Mubo and Bobdubi had been resupplied by air and Allied planners determined the need to relieve some of the logistics burden on their aircraft by seizing Nassau Bay, which was about south of the Allies' ultimate objective. The plan was made following a recommendation from Commander Morton C. Mumma to the Allied South West Pacific Area GHQ that a beachhead at Nassau Bay would greatly shorten the supply line for Australian and American troops fighting in the Salamaua region. Colonel Archibald R. MacKechnie, commander of the 162nd Infantry Regiment, later flew to the Bulolo Valley for a conference with the Australian commanders – Major General Frank Berryman, Lieutenant Colonel John Wilton and Brigadier Murray Moten – to discuss the proposed landings.
During the night of 28 June, the 162nd Infantry Regiment's Intelligence and Reconnaissance Platoon placed lights upon islands lying offshore between Nassau Bay and Mageri Point to guide the invasion flotilla. 'D' Company of the Australian 2/6th Infantry Battalion from Lababia Ridge was required to march to the mouth of the Bitoi River to divert Japanese attention from Nassau Bay. Also, one of 'D' Company's platoons was sent to the landing beach to set up lights to guide the landing craft. 'A' Company of the Papuan Infantry Battalion reconnoitered to Cape Dinga just south of Nassau Bay for the southern flank.
The main Japanese force defending Nassau Bay was III/102nd Battalion, under the command of Major Tsunendo Takamura. Heavily depleted from fighting against Australian forces around Bobdubi, Takamura's battalion consisted of two under strength rifle companies, a machine gun company and a headquarters with a total strength of 180 personnel. In addition, small detachments of marines and engineers were also located nearby. Further afield, the Japanese had established strong posts around the mouth of the Bitoi River and at Cape Dinga, where it was estimated that there were about 375 personnel; in between there were several small outposts. The Japanese units were orientated to defend against a landing in the Huon Gulf, rather than at Nassau Bay. These forces were part of Hidemitsu Nakano's 51st Division, which in turn formed part of Hatazō Adachi's Eighteenth Army.