At the outbreak of World War I, Col. Sir Samuel Augustus Pethebridge took command of the Australian North-West Pacific Expedition, raised to occupy German islands north of the equator. Before the expedition could sail, the British government decided to allow the North Pacific islands to be left in the hands of their Japanese occupiers. Pethebridge suggested that his unit, known as Tropical Force, might be used to relieve the expeditionary force led by Colonel W. Holmes which had captured German New Guinea in the first weeks of the war. This was accepted, and in January 1915, Pethebridge succeeded Holmes as administrator at Rabaul. In January 1917, he contracted malaria which forced his return to Australia, where he died a year later.