The colonization of the Congo Basin is generally regarded as one of the most destructive colonial acquisitions among European powers. This is generally due to the harsh criticisms and general condemnation against Leopold's abuse of the Congo population by other European powers. While it is true that Leopold's colonization was significantly more brutal than other colonial efforts, this is generally a difference in intensity rather than a difference in kind.
Most colonial efforts began with the discovery of natural resources and an effort to monopolize the production/distribution of these resources. With regard to the Congo, this resource was rubber. After identifying these resources, many colonial efforts began with claims of providing humanitarian aid, either by using the Christian church as a cover by advocating for proselytizing (which invariably led to missionary deaths and the need to provide "security" within the country). However, other efforts focused on claims of poor governance or the need to "civilize" indigenous peoples. With regard to the Congo, Leopold used the existence of the Arab slave trade and the need to fight it as pretext. In Africa, this was a common pretext that led European powers to declare a need to colonize an area as a means to prevent Arab slave traders from taking people, though it invariably led to slavery within the colonized area.
As colonial holdings grew more difficult to maintain, especially after World War I, colonial powers generally held onto their colonies by claiming that the indigenous people were not capable of governing themselves and needed preparation. While the Congo is unique in that Leopold personally owned the colony, he was forced to transfer this possession to the Belgian government, which delayed decolonization by claiming a need to prepare the Congolese people. Ultimately, nothing was ever actually done to prepare for decolonization and, like many other colonies, Belgium eventually organized a hasty election and conferred independence on the Congo while withdrawing most of its resources.
The colonial story of the Congo is similar in form to the colonial story of most African nations. The main differences reside in the sheer brutality and cruelty with which Leopold governed the Congo.