Reading "King Leopold's Ghost" by Hochschild is wild. Revelation after revelation.
Like, did you know that "the Independent State of Congo," as it was known once Leopold laid claim to it, was actually Leopold's personal possession? Not, initially, an actual colony of the country of Belgium but his private fiefdom. He referred to himself as its proprietor at times.
How?? First, he set up the "International African Association" (Association Internationale pour l'Exploration et la Civilisation de l'Afrique Centrale), tricking people into thinking this was a real independent non-profit organization. Then, under the pretense of humanitarianism, he hired Henry Morton Stanley to traverse the Congo River and trick local elites into signing treaties and contracts with the King of the Belgians. These false treaties were then put to use in convincing first the USA and then the European powers, during the Berlin Conference of 1884-85, to recognize Leopold as the sovereign of "L'État indépendant du Congo" (the Independent State of Congo). Ironically, the conference also resulted in a pact among the Europeans to put an end to African and Arab slavery.
The death toll of Leopold's forced labor regime, geared towards his personal enrichment via the extraction first of ivory and then rubber, is estimated at around 10 million people. He used these riches, in part, to fund his obsession with architecture, leading to his moniker in his home country, the "Builder King."