On 11 September 1914, Australian troops land in German New Guinea at Bita Paka (near Rabaul). On 21 September, all German forces in the colony surrendered.
German New Guinea consisted of the northeastern part of the island of New Guinea and several nearby island groups and was the first part of the German colonial empire. The mainland part of the territory, called Kaiser-Wilhelmsland, became a German protectorate in 1884.
Other island groups were added subsequently. The Bismarck Archipelago (New Britain, New Ireland and several smaller islands), and the North Solomon Islands were declared a German protectorate in 1885; in the same year the Marshall Islands were bought from Spain for $4.5 million by the Hispano-German Protocol of Rome; Nauru was annexed to the Marshall Islands protectorate in 1888, and finally the Caroline Islands, Palau, and the Mariana Islands (except for Guam) were bought from Spain in 1899. German Samoa, though part of the German colonial empire, was not part of German New Guinea.
Following the outbreak of World War I, Australian troops captured Kaiser-Wilhelmsland and the nearby islands in 1914, after a short resistance led by Captain Carl von Klewitz and Lt. Robert “Lord Bob” von Blumenthal, while Japan occupied most of the remaining German possessions in the Pacific.
The only significant battle occurred on 11 September 1914 when the Australian Naval and Military Expeditionary Force attacked the low-power wireless station at Bita Paka (near Rabaul) on the island of New Britain, then Neu Pommern.
The Australians suffered six dead and four wounded – the first Australian military casualties of the First World War. The German forces fared much worse, with one German officer and 30 local policemen killed and one German officer and ten local policemen wounded. On 21 September all German forces in the colony surrendered.
However, Lieutenant (later Hauptmann) Hermann Detzner, a German officer, and some 20 local policemen evaded capture in the interior of New Guinea for the entire war. Detzner was on a surveying expedition to map the border with Australian-held Papua at the outbreak of war, and remained outside militarised areas.
Detzner claimed to have penetrated the interior of the German portion (Kaiser Wilhelmsland) in his 1920 book Vier Jahre unter Kannibalen (“Four Years Among Cannibals”). These claims were heavily disputed by various German missionaries, and Detzner recanted most of his claims in 1932.
After the Treaty of Versailles of 1919, Germany lost all its colonial possessions, including German New Guinea. In 1923, the League of Nations gave Australia a trustee mandate over Nauru, with the United Kingdom and New Zealand as co-trustees.
Other lands south of the equator became the Territory of New Guinea, a League of Nations Mandate Territory under Australian administration until 1949 (interrupted by Japanese occupation during the New Guinea campaign) when it was merged with the Australian territory of Papua to become the Territory of Papua and New Guinea, which eventually became modern Papua New Guinea.
The islands north of the equator became the Japanese League of Nations Mandate for the South Seas Islands. After Japan’s defeat in World War II, the former Japanese mandate islands were administered by the United States as the Trust Territory of the Pacific Islands, a United Nations trust territory.