Kokoda had been retaken on 2 November, unopposed, the flag raised by Major General George Vasey in a ceremony on 3 November. Supplies were flying in. Wounded were being evacuated by air for the first time in months. The Kokoda Track, until then a pipeline that leaked ninety per cent of its cargo into the jungle, had become a functioning line of communication. But between the Australians and the Japanese beachheads at Buna and Gona lay one more chance for Horii to buy time. He chose the high ground around Oivi, about twelve kilometres east of Kokoda on the track to Sanananda. His men dug in carefully. They had artillery, something the Australians still mostly did not. They had prepared positions. And they had orders to hold long enough for the beachheads to be reinforced from the sea.

On 4 November, Brigadier John Lloyd's 16th Brigade hit the Oivi position and bounced. Well-sited machine guns and well-dug infantry held off several frontal attacks across three days. It was the same lesson Lloyd had bloodied himself against at Eora Village: in New Guinea jungle, frontal assaults against prepared defences were a way to get infantry killed. Vasey watched the situation and, on 7 November, committed Brigadier Kenneth Eather's 25th Brigade to a flanking move. Eather's battalions, on a parallel track to the south, would bypass Oivi entirely and strike the Japanese depth position at Gorari. The two brigades together numbered 3,700 men. Horii's force was smaller and already badly weakened from the four-month retreat, though exactly how weakened was about to become clear.

The 25th Brigade made the turn north on 9 November and hit Gorari on the morning of the tenth. What followed was close-quarters work, hand-to-hand in places, with heavy casualties on both sides. The Japanese defenders were surprised, cut off from their own line of retreat, and fighting under the assumption that the main Australian weight was still at Oivi to their west. By the afternoon of 11 November, the battle was over. Some Japanese broke east toward the Kumusi, some were killed in place, and a smaller number managed to slip through the jungle gaps. Australian casualties came to 121 dead and 225 wounded. The battle honour was awarded to the 3rd, 2/1st, 2/2nd, 2/3rd, 2/25th, 2/31st and 2/33rd Infantry Battalions. Lloyd's 16th Brigade, finally able to press forward when Horii's defenders at Oivi began peeling off to save themselves, took the position that had held them for a week.

The Kumusi River flows out of the Owen Stanleys toward the north coast, crossing the track at a place the Australians called Wairopi, Tok Pisin for wire rope, because of the wire-cable suspension bridge that had once spanned it. Allied bombing had destroyed that bridge weeks earlier. When the broken Japanese force reached the river in the days after Gorari, it was in flood. Survivors described men trying to swim across with weapons and equipment. Many drowned. Major General Horii himself was among the dead, though he is believed to have died further downstream attempting a raft crossing. A significant quantity of Japanese artillery, the mountain guns that had given them the upper hand in every earlier battle, had to be abandoned on the western bank. For four months those guns had bombarded Australians who could not answer; now they sat in the mud while their crews drowned in front of them.

The Australians crossed the Kumusi between 13 and 16 November using whatever they could improvise. Engineers strung flying foxes (a single-cable zip line) and a narrow footbridge between the banks. Engineering stores were thin, so the 25th Brigade went first, one company at a time, establishing a small bridgehead before the 16th Brigade followed. The ad hoc Chaforce, drawn from the 21st Brigade, arrived as reinforcements. By 16 November the river was behind them. What lay ahead was not relief but Buna and Gona, heavily fortified Japanese beachhead positions that would swallow the next two months in a frontal assault that cost more Australian lives than the whole track campaign put together. For the men at Wairopi, the significance of Oivi-Gorari was less about victory than about something simpler: they had pushed the Japanese off the mountains. For the first time since July, they were advancing into country they could see.