In 1884 Germany and Britain established Protectorates in the eastern half of New Guinea and adjacent islands. Germany took the northeast and adjacent islands and Britain took the southeast and adjacent islands. The western boundary of both Protectorates was the 141 degree east longitude. The western section of the island had been annexed by the Dutch in 1828.
From 1884 to 1899 German New Guinea was administered by a private company, the Neuguinea Kompagnie. When the company failed, the Protectorate was formally taken over, as a colony, by the Imperial German Government. In 1914, at the outbreak of World War I, Australia occupied the German colony. Australian military occupation ended in 1921 when the League of Nations declared the territory to be the Australian Mandated Territory of New Guinea. In the south, the British declared their Protectorate to be a British colony in 1888. In 1906 the British handed the colony to the Commonwealth of Australia which renamed it the Australian Territory of Papua.
Following the Japanese invasion in 1942, parts of both New Guinea and Papua were under Japanese or Allied (American and Australian) military occupation. After the war (1945) the Australians administered Papua and New Guinea as one territory, the Territory of Papua and New Guinea, until 1975 when the Territory became the independent state of Papua New Guinea.