Kaiser - Wilhelmsland Kaiser - Wilhelmsland was part of German New Guinea ( German : " Deutsch - Neuguinea " ) , the South Pacific protectorate of the German Empire . Named in honour of Wilhelm II , who was the German Emperor and King of Prussia , it included the north - eastern part of present day Papua New Guinea . From 1884 until 1918 , the territory was a protectorate of the German Empire . Kaiser - Wilhelmsland , New Pomerania , the Bismarck Archipelago , the northern Solomon Islands , the Carolina Islands , Palau , Nauru , the Mariana Islands and the Marshall Islands comprised German New Guinea . Most of the German settlers to Kaiser - Wilhelmsland were plantation owners , miners , and government functionaries , and the number of European settlers , including non - Germans , was never very high . In 1885 , Lutheran and Catholic congregations sent clergy to establish missions , who experienced moderate , but very slow , success with the indigenous peoples . Missionaries and plantation owners alike were limited by tropical diseases , travel and communication barriers . The protectorate was never fully explored by the Germans , although in 1914 , the Imperial German Government mounted an expedition to explore and map the interior . Lutheran missionaries were frequently the first Europeans to explore the interior and examine the different fauna and flora . At the outbreak of war in 1914 , the German protectorate was quickly overrun by British - Australian troops . In 1918 , as part of the settlements ending World War I , Kaiser - Wilhemsland was administered by the Commonwealth of Australia , a British dominion . Natural features . Quaternary glaciers created much of the topography of Kaiser - Wilhelmsland . Recent studies suggest Mount Wilhelm held approximately of glacial ice . Further north , closer to the Equator , the glaciers left behind large rubble fields . The territory of Kaiser - Wilhelmsland was largely mountainous , with Mount Wilhelm the highest peak of the Hagan Range , which separated the protectorate from the British " Papua " . There are several major rivers , notably the Sepik River which drops from the Highlands and winds through lowland swamp plains to the north coast . The Markham River flows from the Finisterre Range and ends in the Huon Gulf . The Huon Peninsula , named for the French explorer Jean - Michel Huon de Kermadec , has raised beaches , usually created by the combination of tectonic coastal uplift and quaternary sea - level fluctuations . The Saruwaged " massif " , with its twin peaks of Bangeta and Saruwaged , dominate the Saruwaged Range ; rugged and steep , the massif reaches , and is surrounded by jungles at its base . Indigenous population . Near Mount Hagen , archeologists have identified the Kuk Swamp ( ) , one of the oldest agricultural drainage sites in Australasia ; the site has been identified as a UNESCO site , and is on the list of recommended World Heritage sites . Linguistic features suggest the origins of the population . Along the southeast coast and in the Markham Valley , the Austronesia family of languages predominate . The two main languages were Kâte and Yabim , with Kâte spoken in the mountainous hinterlands and Yabim on the coastal areas , particularly on coast of the Huon Peninsula . The Non - Austronesia languages are heard most commonly in the mountain regions . Early exploration . The coastline of the northern and eastern portions of New Guinea had been charted by navigators in the early 17th century , and the visible mountain ranges named by British admiralty navigators later in the century . Most German surveying efforts had focused on coastal regions and river basins , where Germans had established plantations . The boundary between Papua and Kaiser Wilhelmsland had been established by a joint British - German expedition in 1909 , the interior had not been mapped . Since then , Papuan gold prospectors had crossed into German territory which , from the German perspective , made the accuracy of the border essential . In late 1913 , the Imperial Colonial Office appointed Hermann Detzner to lead an expedition to survey the border between the British protectorate , called Papua and the German territory and to survey and map the interior . Detzner seemed to be the right man for the job . Detzner ' s mission was also to be the first serious attempt to explore the unknown interior and to evaluate and describe its contents . Settlement by Europeans . In 1882 , the firms of German New Guinea Company and Plantation Society , and the Robertson and Hernsheim Company ( later Hernsheim Company ) secured the German business interests on the Island . The colony was dominated by the German New Guinea Company , and between 1884 and 1899 was actually administered by the company . The plantation owners , most of whom mined copper , or grew such tropical products as coconuts , focused their attention on the coastal regions , leaving exploration of the interior to the missionaries and military explorers . In 1885 – 87 , Johann Flierl established missionary stations in Simbang and Timba Island . After malaria epidemics in 1889 and again in 1891 killed almost half of the European settlers on the coast in Finschhafen , many of the Europeans moved toward Friedrich Wilhelmshafen ( now Madang ) . Flierl established a Mission station at the Sattelberg , in the highlands . In 1890 – 91 , he built the Sattelberg Mission Station there and constructed a road approximately between the station and the Finsch harbor ( " Finschhafen " ) , which cut the traveling time from three days to five hours . Outbreak of World War I . On 4 August 1914 , Britain declared war on Germany . As World War I spread to the Pacific , Australian troops invaded German New Guinea , taking the German barracks in Herbertshöhe ( present day Kokopo ) and forcing the defending German colonial troops to capitulate on 21 September after their defeat at Bita Paka . Reorganization and Australian administration 1920 - 1945 . In 1918 , Kaiser Wilhelmsland and the other territories that comprised German New Guinea ( New Pomerania and the islands of the Bismarck Archipilago ) were administered by the Commonwealth of Australia . Beginning in 1920 , Australia , under a mandate from the League of Nations , governed the former German territory of New Guinea . It was administered under this mandate until the Japanese invasion in December 1941 ( Operation Mo ) . Most of the territory of New Guinea , including the islands of Bougainville , and New Britain , was occupied by Japanese forces before recapture during the final months of the war in the Australian - American New Guinea campaign .