Australian forces were involved in warfare in hyperendemic areas of New Guinea from early 1942 until late 1945. Initially they were ill-prepared and suffered very heavy malaria casualties, even when not engaged in fighting. As a result measures were taken to make the supervision of personal protection (clothes, suppressive atebrin, repellent, mosquito nets) a matter for unit commanders rather than a medical problem. Malariologists were appointed and supervised Malaria Control Units, which were moved in with attacking troops, and Entomological Sections were established, which provided advice on vectors of malaria and other arthropod-borne diseases. In successive campaigns the casualties from malaria decreased substantially, especially after active operations in particular campaigns had ended, except in the Aitape-Wewak area, where field observations suggested that some strains of P. falciparum were resistant to the standard dose of suppressive atebrin. This was confirmed in experiments on human volunteers at a malaria research unit in Australia.