The Battle of Roosevelt Ridge was fought between 21 July and 14 August 1943 between US and Japanese forces in the Salamaua area of the Territory of New Guinea during World War II.

Progress was slow, though, and this – coupled with inter-Allied service politics – strained relations between US and Australian commanders before the ridge was eventually carried in mid-August.

[1] Over the course of several days in early July, one reinforced battalion of the 162nd Infantry Regiment, under the command of Colonel Archibald MacKechnie,[2] made an unopposed amphibious landing at Nassau Bay.

Elements of the Papuan Infantry Battalion (PIB) provided flank security and after the landing, the US troops established a beachhead at Nassau Bay.

[9] Tasked with securing a beachhead around the bay, and providing artillery support to the Australians fighting around Komiatum and Bobdubi, elements of the PIB under the command of Captain Ernest Hitchcock, were pushed ahead of the US force to scout the area, and around 14 July they succeeded in locating several Japanese elements around Boisi including marines and soldiers from the III Battalion of the 66th Infantry Regiment, which were orientated to defend against a landing around Tambu Bay.

Three days later the main US drive on Tambu Bay commenced, with two companies striking towards the north via an inland route, while another hand-railed the coast, guided by PIB scouts.

The advance was slow and on the coast, the US company was held up around Lake Salu while a platoon from the PIB destroyed one of the Japanese outposts around Boisi on 20 July.

The US company was then able to occupy Boisi, but found itself receiving harassing fire from Roosevelt Ridge, which stretched from the sea about 1.8 kilometres (1.1 mi) to the west.

[11] In an effort to support the advancing infantry, on the night of 20/21 July two artillery pieces from the Australian 2/6th Field Regiment were landed at Tambu Bay.

Working in conjunction with the larger US 105 mm pieces, these guns were later used to help reduce the Japanese defences around the Salamaua region, with aerial observation being provided by Boomerang fighters from No.

Pushing to the west and then hooking back towards a spur that led towards a small knoll on the crest, the Americans sought to find a break in the Japanese defences.

Heavy preparatory fires fell on Japanese position to the front and flanks, before the attack began with two companies pushing forward.

Overnight, the Japanese attempted to reinforce the position with 200 men from the 238th Infantry Regiment, but the following morning the two US companies were able to effect a link up at the western end of the ridge.

Bad weather hampered their efforts, but the airfield and surrounding area was eventually secured on 11 September, by Australian forces from the 15th and 29th Brigades, after a brief engagement with the Japanese rearguard.