Before the mid-19th century, European intervention in much of tropical Africa was extremely difficult because of the disease gradient. The combination of malaria and yellow fever commonly killed off half of European troops stationed in West Africa each year. It was the reverse of the conquest of the Americas, where introduced diseases wiped out 50 million indigenous Americans, opening the land to settlement and greatly reducing the ability to resist. This was much less of a problem in temperate southern Africa, accounting for the Dutch being able to set up a colony there in the 17th century.The political situation was also important. Germany did not exist as a nation until 1871, when the German Empire was declared, following the decisive defeat of France in the Franco-Prussian War of 1870. Germany united into a single nation under the former king of Prussia, who became kaiser (meaning emperor). Previously, Germany had been a linguistic and cultural region fragmented into a welter of kingdoms, dukedoms, margraviates, bishoprics, and free cities.At that time, most of Africa remained independent. The French controlled Algeria and Senegal, the Portuguese had a considerable presence in Angola and Mozambique, the British controlled much of South Africa and were establishing a protectorate over Egypt, Spain had some small territories and there were sites along the Gulf of Guinea that had belonged to various European states since the 1400s, including the Dutch, Danes, Swedes, French, and Portuguese. By the 1870s, the British controlled most of these.In 1884, Prince Otto von Bismarck, the German chancellor, brought the plenipotentiaries of all major powers of Europe together, to deal with Africa’s colonization in such a manner as to avoid provocation of war. This event, known as the Berlin Conference of 1884-1885, galvanized a phenomenon that came to be known as the Scramble for Africa. The conference established two fundamental rules for European seizure of Africa. The first of these was that no recognition of annexation would granted without evidence of a practical occupation, and the second, that a practical occupation would be deemed unlawful without a formal appeal for protection made on behalf of a territory by its leader, a plea that must be committed to paper in the form of a legal treaty.This began a rush, spearheaded mainly by European commercial interests in the form of Chartered Companies, to penetrate the African interior and woo its leadership with guns, trinkets and alcohol, and having thus obtained their marks or seals upon spurious treaties, begin establishing boundaries of future European African colonies. The ease with which this was achieved was due to the fact that, at that point, traditional African leadership was disunited, and the people had just staggered back from centuries of concussion inflicted by the slave trade. Thus, to usurp authority, to intimidate an already broken society, and to play one leader against the other was a diplomatic task so childishly simple, the matter was wrapped up, for the most part, in less than a decade. The German role in this complicated drama was something of an enigma. The German Empire would prove to be the most short-lived of all, because, along with the Russian and Ottoman Empires, it did not survive World War I. In 1919, Germany lost all of its African colonies, which then accrued as League of Nations mandated territories either to France or Britain. The mandate over German South West Africa, the future Namibia, was placed under British control by proxy, and its day-to-day administration was handled from South Africa. Ultimately, South Africa absorbed South West Africa as a virtual province and resisted pressure to cede authority to the United Nations for decades.