Leopold II obtained international recognition of the Congo Free State in 1885 and from the early 1890s converted it into an extraction economy based on wild rubber. Quotas were imposed on villages and enforced by the Force Publique and by armed sentries employed by concession companies: hostages were taken, villages burned, and - as the CEPR summary of the economic-history literature records - sentries were required to produce a human hand for every cartridge fired, to prevent ammunition being used for hunting. Edmund Morel publicised the system from the shipping records, and Roger Casement's consular report of 1904 confirmed the accusations; the Congo Reform Association that the two founded is often described as the first mass human rights organisation. A commission of inquiry appointed by Leopold reported in 1905, and under pressure from Belgium, Britain, the United States, France and Germany the Belgian state annexed the territory in 1908, paying Leopold substantial compensation. The regime lasted about fourteen years in its most intense form and its effects on wealth, health and institutions in the former concession areas are measurable more than a century later.
Leopold II of Belgium held the Congo basin as a personal possession and extracted rubber and ivory through forced labour enforced by the Force Publique and concession company militias
No usable starting figure exists, and the dispute over it is central to the historiography. E. D. Morel's contemporary estimate of 20 million, from which the familiar claim that half the population died derives, rests on no enumeration; the first colonial census, in 1924, counted about 10 million. Louis and Stengers call the starting figures 'wild guesses', Vansina and Hochschild accept a decline on the order of ten million, and recent demographic work suggests a documented decline of about 1.2-1.5 million. With the base itself contested by a factor of two, a percentage would be meaningless.
The upper figure is the estimate attributed to Hochschild and Vansina and reported in the CEPR summary and by EBSCO: roughly ten million people, about half the population of the Congo, dead between 1880 and 1920 from violence, disease, starvation and collapsed birth rates. It is a reconstruction from post-1908 censuses projected backwards, not a count, and it covers a longer period than Leopold's rule alone. The lower figure reflects more conservative readings that confine the estimate to the concession districts and to the years of the rubber regime and that attribute a larger share of the epidemic mortality to causes independent of the labour system. No contemporary authority counted the dead.
The Casement report of 1904, the 1905 commission of inquiry and the missionary photographic record documented hostage-taking of women and children, the severing of hands, floggings with the chicotte, the burning of villages and killings by Force Publique soldiers and company sentries enforcing rubber quotas.
Dem. Rep. Congo