Japanese land forces continued to advance in the Solomon Islands and New Guinea. From July 1942, a few Australian reserve battalions, many of them very young and untrained, fought a stubborn rearguard action in New Guinea, against a Japanese advance along the Kokoda Track, towards Port Moresby, over the rugged Owen Stanley Ranges. The militia, worn out and severely depleted by casualties, were relieved in late August by regular troops from the Second Australian Imperial Force, returning from action in the Mediterranean theater. In early September 1942 Japanese marines attacked a strategic Royal Australian Air Force base at Milne Bay, near the eastern tip of New Guinea. They were beaten back by Allied (primarily Australian Army) forces.
Try to answer this question if possible (otherwise reply "unanswerable"): What forces releived the worn Australian reserve battalions?
Second Australian Imperial Force