It would be helpful to learn about the pre-war colonial divisions of the island of New Guinea (it was divided into 3 sections, Dutch, German, and British), the wartime significance of New Guinea (Japanese foothold and March to Port Moresby, US airbases in Hollandia) the handover of West and the postwar UN decision that PNG should be an Australian mandate (many underdeveloped but war-impacted areas were made 'mandates' of colonial, great, and middle-powers. In the context of the time, Australia was considered a 'middle power') until independence was viable.

That gives you some context as to why Australians, Germans, British, and Dutch are romping all over the island.

But otherwise, it is a pretty encapsulated story of a handful of individuals that's easy to follow