Explain the techniques/strategies that leopold used to get the resource out of the congo

Leopold II, after resigning as the King of the Belgians, became the founder and single owner of the Congo Free State where he amassed a huge fortune by exploiting its natural resources such as the ivory, white material from the tusks and teeth of elephants, and rubber, gathered by the native population of the Congo.  

Leopold II founded the Congo Free State, a large state in Central Africa ruled by him and operated separate from Belgium, under the auspices of the International Association of the Congo, to monopolize the resources this  entire State  by securing the European community that he was involved in humanitarian and philanthropic work and not in a private project on his own behalf.