track." Throughout this fighting, Australian resistance was increasing in strength and becoming better organised while the Japanese were showing signs of feeling the strain of their own lengthening supply line. Both sides, however, were beginning to suffer the effects of reduced effectiveness caused by exhaustion and sickness entailed by operating over such harsh terrain. Moreover, the Australian build-up, while still relatively modest, proved impossible to sustain via the only supply line stretching over the mountains, which depended on native carriers to manhandle rations and ammunition forward, and to evacuate the sick and wounded to the rear. The commander of 1st Australian Corps at Port Moresby, Lieutenant General Sydney Rowell, accordingly decided to withdraw the tired 39th Battalion on 5 September to relieve the problem. After another hard-fought stand at Brigade Hill between 8 and 10 September, Potts handed over command to Brigadier Porter, who decided on a further withdrawal to Ioribaiwa. Here the Japanese attacked next day but made little progress. In fact, severe fighting continued around Ioribaiwa for a week. But the Japanese advance was losing impetus, while the Australian defence was gaining in strength through the arrival of more units of the 7th Division. Command of the forward area passed to Brigadier Ken Eather, leading the 25th Brigade, AIF, on 14 September. In addition to its normal battalions (2/25th, 2/31st and 2/33rd), that brigade also had attached the 3rd Battalion and the 2/1st Pioneer Battalion ? a total of 2,500 combat troops. It was to continue his defence