Ioribaiwa was a small village, atop a ridge, on the Kokoda Trail, approximately 50 kilometres north-east of Port Moresby. It was the site of one of the many delaying actions fought by Australian troops during their withdrawal along the Kokoda Track. Fearing encirclement, and doubting the tactical advantage offered by his existing positions on Nauro Ridge, Brigadier Selwyn Porter began withdrawing his 21st Brigade to Ioribaiwa on 11 September 1942. It was a brigade only in name consisting of the remnants of the 2/14th and 2/16th Battalions, numbering less than 300 men, and the inexperienced 3rd Battalion. The Japanese followed close behind, and many were killed in ambushes set by the withdrawing Australians. Porter's weary force was reinforced at Ioribaiwa on 14 September by fresh troops from Brigadier Ken Eather's 25th Brigade. Eather had been ordered to take command at Ioribaiwa and launch a counter attack with his battalions. As they began to advance on the 15th, however, the Japanese renewed their own attack. They established strong footholds on both flanks of the Australian position and a series of strong attacks along the trail was forcing back the composite battalion that had been formed from the 2/14th and 2/16th. With all of his troops committed to simply holding the Japanese, and even then still yielding ground, Eather had no capacity to follow-through with his plans. He thus requested permission to withdraw to Imita Ridge thereby providing him with the opportunity to establish a strong defensive position as a base to renew his counter-attack. The Australians broke contact and withdrew throughout 16 September, it would be their last withdrawal on the trail.