 Although successful the operation was arguably not well managed , and the Australians had been effectively delayed by a half @-@ trained native force . Regardless the Australians had prevailed not least of all because of their unexpected ability to fight in close terrain , while the outflanking of the German positions had unnerved their opponents . The losses of the AN & MEF were light in the context of later operations but were sufficiently heavy given the relatively modest gain . These losses were further compounded by the unexplained disappearance of the Australian submarine HMAS AE1 during a patrol off Rabaul on 14 September , with 35 men aboard . 
