Now I'm certainly not saying that what the UK did was equivalent to slavery, but I just don't see how the above argument is particularly valid.
If you look at actual slavery throughout history, you generally see large populations of the former slaves staying where they were brought even...
Pagans didn't necessarily deny the existence of other gods, but simply believed that theirs were better. If one tribe is conquered by another, than the logical conclusion is that their gods were better after all, easing conversion into the new faith.
Followers of the Abrahmic faiths...
America's ass saved by France: 1
France's ass saved by America: 2
This deficit must be rectified before France can be respected in the eyes of the United States ;)
I don't know about underpopulated, but underdeveloped is definitely a factor. The british tried to outlaw industry in the 13 colonies, in order to keep it all at home. I imagine that would continue for a while at least. Enough time to set the Americans back enough that, thanks to lack of tariff...
Have the British steal Alaska the way the Russians feared (which was why they sold it to the USA), then have the British sell it to Japan sometime later when they were allied.
Some kind of controls over the media, that prevent them from informing the people, or at least putting some kind of positive spin on the affair: "Look how we are massacring them! This is proof that they are desperate!"