The Congo Free State is a definite example of a case where even European empires were disgusted by abuse of conquered peoples. Beyond George Washington Williams, Joseph Conrad and Mark Twain, legendary British author Sir Arthur Conan Doyle wrote an account of the atrocities in his work The Crime of The Congo, calling them some of the worst abuses he had ever heard being committed on human beings up to that time. The only reason the Congo evils were forgotten by many is due to World War I. Until 1914, Belgium was MASSIVELY tarnished in image (since it was THEIR king after all who had overseen this), and from reports I've read some abuses continued for a year or more after the Belgian government took over in 1908. It is sad though that discussion on the treatment of ruled peoples under imperialism (and how other nations should respond) didn't start a whole lot until this debacle, with the Ottoman atrocities of Greeks among others in the 19th Century possibly being one exception.