Principle of Effective Occupation
The principle of effective occupation stated that powers could acquire rights over colonial lands only if they actually possessed them: in other words, if they had treaties with local leaders, if they flew their flag there, and if they established an administration in the territory to govern it with a police force to keep order. The colonial power could also make use of the colony economically. This principle became important not only as a basis for the European powers to acquire territorial sovereignty in Africa, but also for determining the limits of their respective overseas possessions, as effective occupation served in some instances as a criterion for settling disputes over the boundaries between colonies. However, as the Berlin Act was limited in its scope to the lands on the African coast, there were numerous instances where European powers claimed rights over lands in the interior without demonstrating the requirement of effective occupation articulated in Article 35 of the Final Act.

The European colonization of Africa was one of the greatest and swiftest conquests in human history. In 1870 roughly 80 percent of Africa south of the Sahara Desert was governed by indigenous kings, chiefs, and other rulers. By 1910 nearly this entire huge expanse had become European colonies or land, like South Africa, controlled by white settlers. The bloodiest single episode in Africa's colonization took place in the center of the continent in the large territory, known as the Congo.
For centuries African slave dealers had raided parts of this area, selling their captives to American and European captains who sailed Africa's west coast, and to traders who took slaves to the Arab world from the continent's east coast. But heat, tropical diseases, and the huge rapids near the mouth of the Congo River on the Atlantic had long kept the Congo's interior a mystery to Europeans. From 1874 through 1877 the British explorer and journalist Henry Morton Stanley (1841904) crossed Africa from east to west. For much of the journey he floated down the river, mapping its course for the first time and noting the many tributaries that, it turned out, comprised a network of navigable waterways more than 7,000 miles long.
Although Stanley is best known as the man who found Livingstone, his trip across the Congo basin was the greater feat of exploration and had far more impact on history. As he headed back to England, Stanley was assiduously courted by King Leopold II of Belgium. Leopold (1835909) had ascended to the throne in 1865. A man of great charm, intelligence, ruthlessness, and greed, he was openly frustrated with inheriting the throne of such a small country, and in doing so at a time in history when European kings were rapidly losing power to elected parliaments. He had long wanted a colonial empire, and in Stanley he saw someone who could secure it for him. The Belgian cabinet of the day was not interested in colonies. But for Leopold this posed no problem; he would acquire his own.
In 1879 Stanley returned to the Congo as Leopold's agent. He built outposts and a road around the river's rapids and, using small steamboats, he traveled up and down the great river and its tributaries. Combining gift-giving with a show of military force, he persuaded hundreds of illiterate African chiefs, most of whom had little idea of the terms of the agreement to which they were ostensibly acceding, to sign away their land to the king.
Stanley made his way back to Europe with a sheaf of signed treaties in 1884. Meanwhile, Leopold had already begun the job of persuading first the United

Nsala, of the district of Wala, looking at the severed hand and foot of his five-year-old daughter, a victim of the Anglo-Belgian India Rubber Company (A.B.I.R.) militia. [ANTI-SLAVERY INTERNATIONAL]
States and then all the major nations of Europe to recognize his claim. A master of public relations who portrayed himself as a great