As veteran Second Australian Imperial Force formations including Brigadier Arnold Potts' 21st Brigade arrived from Australia to reinforce Maroubra Force, the first major action of the campaign took place around Isurava. This was followed by actions around Templeton's Crossing, Efogi and Ioribaiwa as the Japanese penetrated as far south as Imita Ridge, which was only a short distance from Port Moresby. In late September and early October, after reverses around Milne Bay and Guadalcanal, the Japanese went onto the defensive as the strategic situation in the Pacific began to turn against them, and the Australians were able to launch a cautious counter-attack which saw them retake Kokoda unopposed on 2 November 1942. Finding the airstrip in a state of disrepair, the Australians began efforts to reopen the airstrip. As supplies began to arrive, the logistical burden of trekking supplies up the track was alleviated and the Allied counter offensive picked up pace. This was followed by heavy fighting around Oivi and Gorari, which proved to be the final action of the Kokoda Track campaign prior to the Battle of Buna–Gona as the Japanese were pursued back towards their beachheads on the northern Papuan coast.