Based around the Pacific Islands Regiment, the Australian Army's units in Papua New Guinea had a dual identity: integral to Australia's defence, but also part of its largest colony, and viewed as a foreign people. The Australian Army in PNG defended Australia from threats to its north and west, while also managing the force's place within Australian colonial rule in PNG, occasionally resulting in a tense relationship with the Australian colonial government during a period of significant change. In Guarding the Periphery: The Australian Army in Papua New Guinea, 1951–75, Tristan Moss explores the operational, social and racial aspects of this unique force during the height of the colonial era in PNG and during the progression to independence. Combining the rich detail of both archival material and oral histories, Guarding the Periphery recounts a part of Australian military history that is often overlooked by studies of Australia's military past.