Leopold was the founder and sole owner of the Congo Free State, a private project undertaken on his own behalf. He used explorer Henry Morton Stanley to help him lay claim to the Congo, an area now known as the Democratic Republic of the Congo. At the Berlin Conference of 1884–1885, the colonial nations of Europe authorized his claim by committing the Congo Free State to improving the lives of the native inhabitants. From the beginning, however, Leopold essentially ignored these conditions. He ran the Congo using the mercenary Force Publique for his personal enrichment. He used great sums of the money from this exploitation for public and private construction projects in Belgium during this period. He donated the private buildings to the state before his death, to preserve them for Belgium.
Leopold extracted a fortune from the Congo, initially by the collection of ivory, and after a rise in the price of rubber in the 1890s, by forced labour from the natives to harvest and process rubber. Under his regime millions of the Congolese people died; modern estimates range from 2 to 15 million, with a consensus growing around 10 million.