The ridge ended up named for a battalion commander who would be relieved of duty before it fell. Major Archibald Roosevelt, son of a former U.S. president, led the 3rd Battalion of the 162nd Infantry Regiment when his men first looked up at the long, jungle-covered spur that stretched about 1.8 kilometers west from the sea above Tambu Bay in the Territory of New Guinea. For three weeks in the summer of 1943, his Americans would fail to take it. Hand grenades rolled down steep slopes. Mortars dropped in preset patterns. Hidden small-arms positions opened up the instant a man's helmet crested the skyline. And then, in mid-August, the Americans dragged 40mm Bofors guns onto a knoll opposite the ridge and fired them horizontally into the Japanese line.
In early July 1943, a reinforced battalion of the U.S. 162nd Infantry Regiment, commanded by Colonel Archibald MacKechnie, landed unopposed at Nassau Bay about 15 miles south of Salamaua. The Papuan Infantry Battalion screened the flanks. The Australian 2/6th Infantry created a diversion. For a moment the operation looked like inter-allied cooperation working. Then it stopped looking that way. Disputes flared between Major Roosevelt and Brigadier Murray Moten of the Australian 17th Brigade over whether the Americans reported to Australian command. MacKechnie was dismissed. A new ad hoc U.S. formation under Brigadier General Ralph Coane was placed under Australian Major General Stanley Savige's 3rd Division. The Americans crossed the Bitoi River and pushed north along the narrow isthmus east of Lake Salus toward Tambu Bay.
Around 14 July, Papuan Infantry Battalion scouts located Japanese marines and soldiers of the 66th Infantry Regiment's III Battalion around Boisi, positioned to stop a landing at Tambu Bay. But the real problem was above. Soldiers who had fallen back from Mubo had established themselves along a ridge that looked down on the whole bay — perfect artillery observation, perfect fields of fire. Savige, the Australian in overall command, suggested attacking from the west so the Americans would be moving downhill. Coane chose the eastern assault. On 20 July, two companies attacked. Grenades came rolling down the slope. Mortars dropped exactly where American troops would have to halt. When they reached the crest, small-arms fire from concealed positions drove them back. A second attempt the same day also failed. Two days later the Americans withdrew.
The Australians hauled artillery to Tambu Bay. On the night of 20-21 July two guns from the 2/6th Field Regiment came ashore, two more on 24 July, a second troop the week after. Working alongside the larger American 105mm pieces, and spotted from CAC Boomerang fighters of No. 4 Squadron RAAF, they began pounding Japanese positions around Salamaua. Japanese estimates put 4,000 rounds on their own positions during this period. The Americans tried Roosevelt Ridge again on 27 July with E Company, flanking up a creek line. Same result: onto the crest, into the fire, stopped on a shoulder of ground they could not leave. F Company joined them on 28 July. Same result. For days the troops dug in while Japanese tracer hissed overhead in the dark. Douglas MacArthur intervened. Coane and Roosevelt were both replaced. MacKechnie returned to command the 162nd.
On 12 August, fresh orders went out. The next morning the 2nd Battalion under Major Arthur Lowe attacked the southern slope while Major Jack E. Morris' 3rd Battalion struck at the eastern part of adjoining Scout Ridge. Preparatory artillery fell on the Japanese front and flanks, and this time two companies penetrated the perimeter in three places. Japanese losses: 39 killed. American losses: 25 killed or wounded. Overnight, 200 men from the Japanese 238th Infantry Regiment tried to reinforce the position. The next morning, the two American companies linked up at the ridge's western end. And then came the decisive, almost surreal image of the whole battle — 40mm Bofors anti-aircraft guns, dragged to the top of a knoll opposite the ridge, muzzles levelled flat, firing directly into the Japanese bunkers. The explosive shells tore apart the jungle and the defenders together.
Mount Tambu fell on 18 August. The Allied drive on Salamaua rolled forward. The whole Salamaua campaign had been a deliberate diversion to pull Japanese reinforcements away from Lae, and it worked — the Japanese moved an estimated 5,000 to 6,000 troops into Salamaua by sea, then abandoned the bomb-damaged town when the Allies landed at Lae and dropped paratroops on Nadzab in September. Australian losses for the entire campaign came to 1,083 killed or wounded, with 343 dead. Japanese losses were 8,100, with 2,722 killed. The 162nd Regiment lost 81 killed and 396 wounded across the whole operation. Roosevelt Ridge itself is today part of the coastal hinterland of Morobe Province, unmarked, reclaimed by jungle, still hard to see from any angle unless someone who fought there, or someone who read about it, happens to be pointing.
Located near 5.50 S, 141.00 E in the coastal ridge country south of Salamaua in Morobe Province, Papua New Guinea. Tambu Bay and the spur of Roosevelt Ridge sit along the Huon Gulf coast. Flying at 3,000 to 5,000 feet AGL on clear mornings shows how the ridge commands the bay below. Lae/Nadzab Airport (LAE/AYNZ) is 40 km north. Rain and orographic cloud build rapidly after mid-morning in the wet season; early flying is essential.