It was essentially European imperialism which ended slavery

A series of passages from the recently read Black Rednecks and White Liberals by Thomas Sowell. Combative to the point of provocative but as usual crammed with unexpected facts or interpretations of facts. Page 134.

Even independent non-Western nations were pressured to end slavery, both directly and by a desire not to be embarrassed in the eyes of the world — meaning, during the nineteenth century, mostly the powerful European world. In short, where European and European-offshoot societies held direct and effective power in the nineteenth century, slavery was simply abolished. But where the Western world’s power and influence were mediated, reduced or otherwise operated only indirectly, there non-Western peoples were able to fight a long war of attrition and evasion in defense of slavery—a war which they had, however, largely lost by the middle of the twentieth century, but which they had not yet wholly lost even at the beginning of the third millennium, when vestiges of slavery remained in parts of Africa.

Despite all this, those with an instrumental view of history have managed to turn things upside down and present slavery as an evil of “our society” or of the white race or of Western civilization. One could as well do the same with murder or cancer, simply by ignoring these evils in other societies and incessantly denouncing their presence in the West. Yet what was peculiar about the West was not that it participated in the worldwide evil of slavery, but that it later abolished that evil, not only in Western societies but also in other societies subject to Western control or influence. This was possible only because the anti-slavery movement coincided with an era in which Western power and hegemony were at their zenith, so that it was essentially European imperialism which ended slavery. This idea might seem shocking, not because it does not fit the facts, but because it does not fit the prevailing vision of our time.