Major Cameron arrived to take over Maroubra Force which by the first week of August had grown to 550 men, mostly of 39th Battalion. Leaving a reserve at Deniki, Cameron now moved with 430 men to obey his orders to retake Kokoda. On 8 August, with his headquarters company and one other, he advanced directly down the track from Deniki towards Kokoda. A second force of one company under Captain Bidstrup moved north east to Pirivi to block the track by which Japanese reinforcements might come from the north coast to Kokoda. Between these two Australian forces was a third one, A company under Captain Symington. A Company marched along another track, unknown to the Japanese, that led from Deniki to Kokoda.

Cameron's force on the main track bumped into a Japanese battalion coming the other way. By coincidence the Japanese battalion commander, Colonel Tsukamoto, had begun his attack on Deniki, where he knew the Australians to be, on the same day Cameron commenced his own advance. Tsukamoto had 522 men of 1/144 Battalion. Including Japanese combat engineers who fought Bidstrup's company and small signals and medical detachments, and an artillery platoon with one mountain gun, about 660 Japanese were engaged against 430 Australians.

Soon realising he was considerably outnumbered on the main track Cameron withdrew to Deniki. Tsukamoto, surprised to find the Australians had advanced on him when he expected to be the attacker, slowly and carefully followed Cameron's withdrawal. On the central track Symington found no Japanese at all until he entered Kokoda. There he encountered a platoon of Japanese engineers who did not stay to fight but retreated along the track to Pirivi. Symington's men dug in on the ridge overlooking the Kokoda airstrip on the same ground Owen had defended nine days before.

The Japanese planned to establish a supply dump at Kokoda. For this reason a company of Japanese engineers was in the area improving their supply line. One platoon was building a bridge near Pirivi when Bidstrup's company, which was the easternmost of the three pronged Australian attack, ran into them. The Japanese were reinforced later by another engineer platoon, the one which Symington saw leaving Kokoda in the direction of Pirivi. Bidstrup fought the Japanese engineers until dark when he too withdrew to Deniki.

By 9 August, both commander's plans had been confounded. Cameron, like Tsukamoto, had expected to be the attacker but then found himself under attack. His two outer prongs had been repulsed and the central one, under Symington, was holding Kokoda but cut off from the rest of Maroubra Force. Tsukamoto brought the main body of his battalion up to Deniki but was reluctant to make his attack until he was sure Kokoda was cleared of what he believed was a small force of Australians. He sent back just one company to retake it. This company proved insufficient, all its attacks over that day and the following night were repulsed.

Because Cameron was unsure if Symington was even in Kokoda, no consideration was given to the possibility of flying reinforcements into Kokoda airstrip. On 10 August Symington, having had no communication at all with Cameron and low on ammunition and food, decided to withdraw to Deniki. As the most direct routes were blocked his company eluded the Japanese by heading west across the airstrip then south towards Deniki. Total Japanese casualties for the three days fight were 21 killed and 44 wounded. The Australians lost 23 killed and 17 wounded.

The second Kokoda engagement had notable strategic consequences out of all proportion to the size of the force engaged. Cameron's bold attack on Kokoda came as a surprise, not just to Tsukamoto, but also to his superiors in Rabaul who did not anticipate there would be many Australians on the north side of the Owen Stanley Range. Hyakutake, 17th Army commander, reasoned that if the Australians were bold enough to retake Kokoda, even if only briefly, then they must have a large force, estimated to be 1200 strong. This first prompted the Japanese to consider the idea of postponing the attack on Port Moresby until more troops arrived in Papua, more supplies were accumulated, and Milne Bay was taken. This line of thinking was reinforced when news came in that the American landing at Guadalcanal, on 7 August, would be a greater problem for the Japanese than first thought. By 16 August the decision to postpone the attempt to take Port Moresby was made in Rabaul. Senior Japanese officers interviewed after the war thought that the factor most influencing the postponement was not Guadalcanal but rather 'stronger than anticipated Australian resistance at Kokoda.