At the instigation of Portugal, the Berlin Conference was convened by the German Chancellor Otto von Bismarck, with 13 European powers and the United States represented. Its purpose was to establish a mutually agreed protocol for the colonization of Africa. The Conference reached agreement regarding some existing conflicts between the participating powers. Resolutions passed were to end slavery on the continent, and assign the huge area of Congo Free State to Leopold II of Belgium. Most importantly, it established the ‘Principle of Effective Occupation’, with a colonizing power having to demonstrate some form of political and administrative control. This provision acted as an accelerant for the ‘Scramble for Africa’, which followed the conference, as colonial powers previously content with coastal trading bases rushed to claim dominion over vast territories in accordance with the Principle. Whereas in 1870, only 10 per cent was under colonial control, by 1914 that proportion was 90 per cent.