Hello, I have recently gotten into a discussion about whether yes or not was the king Leopold II of Belgium a socialist or not. Now I am not a historian myself but from my brief research I could not find any sources claiming that he was. It actually seems that he was the opposite. Building his own private colony while his own country was growing more and more socialist becouse of his policies. Can somone educate me please on this one becouse I'm really interested.
This is an extremely difficult question to answer as it is very, very charged here, and my own biases wil undoubtedly come into play here. But no, no he wasn't. There are many interpretations of socialism, but I will use the view that socialism is an ideology that advocates for the means of production (land, labour, capital etc.) to be owned by a community and for profits to be distributed fairly.
So the Belgian Congo was firstly a private entity owned by the King himself who profited massively off it. This is about as far from a socialist model of production as you can get. The Congolese were essentially the serfs of the King, who violently repressed dissent and used violence to coerce production. A capitalist, even feudalist and authoritarian, racist, colonial terror-state is decidedly NOT socialist. Socialism would be the King instituting public ownership of land and resources and giving up his private property, not having his private army cut off hands as punishment for failing to meet production quotas and overseening millions of deaths for personal profit.
Secondly, socialism opposes hierarchies deemed as unjust. Power is supposed to come from democratic elections of officials accountable to the public. This is in clear contrast to a monarchy, where power is derived from divine right, backing from a small economic elite, family name, clerical support, and support from the Army etc. A king is not very accountable to a people who never elected him (obviously exceptions here but that will be a major digression and probably go outside the boundaries of your question).
The reason you could not find any sources for King Leopold being a socialist is that no serious historian would in their wildest dreams call him one. I'm not a historian myself, merely a history student, but this is all based on first-year studying for a Bachelor's. My main information comes from Tignor et. al. Worlds Together, Worlds Apart, 5E, and Robert Paxton's Anatomy of Fascism for it's disseration of authoritarian regimes in contrast to fascism, which I used to compare authoritarianism to socialism.
I also want to write on why you came across this talking point. It's 1) because the person(s) you discussed this with lack knowledge and insight on the topic. Sadly political theory and science is a very, very misrepresented topic online and in media. Take fascism: everything and everyone will at one point be accused of "doing fascism" or "being a fascist" when in reality it's a clearly defined political ideology, distinct from authoritarian right-wing dictatorships.
There is a worrying trend online of conflating socialism with the "state doing stuff". This one-dimensional analysis will often lead people to concluding that fascism=socialism because it utilized state power to achieve it's goals (every political ideology achieves it's desired results through interactions with the state, be it reducing or increasing state power). Belgian Congo being an authoritarian private colonial state who oppressed it's population will therefore be seen by some, acting in good faith or not, to be socialist, though this is going against all serious academic literature out there.
As a follow up question, how (strongly) did the actual socialist/communist movement in Belgium react to his crimes in the Kongo and did it help their cause in any quantifiable way, such as increase in party membership and so on? I’m mostly curious whether this was an important topic in working class politics and, if so, what the main concerns and arguments were.