sentences:  In the 1870s, just before the onset of the Scramble for Africa, European exploration of the Congo Basin was carried out, first led by Henry Morton Stanley under the sponsorship of Leopold II of Belgium.Leopold formally acquired rights to the Congo territory at the Berlin Conference in 1885 and made the land his private property, naming it the Congo Free State.During the Free State, his colonial military unit, the "Force Publique," forced the local population to produce rubber.