Explanation: While all of the European powers in Africa in the 19th and early 20th century were varying degrees of exploitative and genocidal under the excuse of 'civilizing' Africans, the Belgians take the cake for sheer pointless fucking cruelty. King Leopold II and the 'Congo Free State' engaged in... truly horrific practices that beggar belief. Amputations, reprisal murders for not meeting quotas, casually exterminating literal millions of human beings.
It's one of the ugliest parts of an already quite ugly part of history.
Concensus is that is was not so much "the Belgians", but mostly king Leopold II and his band of mercenaries. The Belgian government fucked up by allowing it to persist for so long.
Lots of members of civil society and private companies participated in the atrocities though. And Belgium has been a democracy since its independence, so "the people" are further responsible by being complacent despite contemporary reporting on the atrocities (especially from British investigators as I remember it).
Then the Belgian government continuously failed the Congolese people, especially with the decolonization process which was rushed and ill-prepared which led to a civil war and the rise of Mobutu.
In Rwanda Belgium was one of the actors who cowardly failed to act to prevent genocide.
To say "it's the king" or "it's the government" is way too easy. The country as a whole is responsible for what happened to the Belgian Congo.