Here we have the learned Atheist101 declaiming:

"MFW someone on reddit actually defense [sic] colonialism which enslaved everyone that wasnt [sic] white"

[https://www.reddit.com/r/unitedkingdom/comments/6id413/comment/dj5iiyl]

No evidence is given, but of course we must believe him since he "live and breathe this shit bud" and claims to have a degree in political science, presumably having submitted his thesis in crayon.

Back in the real world slavery was done by people of every hue to people of every hue, and there was certainly plenty within the various European empires, but to say that colonialism enslaved "everyone that wasnt white" is obviously wrong. You can prove this very simply by pointing out a few of the non-white people that were not enslaved: for example Captain John Perkins a non-white, and non-enslaved, Royal Navy officer who gained his first command in 1778.

But perhaps attitudes changed after 1778? Presumably not in 1807 with the abolition of the slave trade, nor in 1824 when Britain defined participation in the slave trade as piracy and punishable by death, nor in 1833 with the abolition of slavery throughout the empire.

Or perhaps this powerful "white" empire was still not powerful enough to enslave everyone that wasn't white up to the 1830s. If this is the case then surely it must have happened as the largest ever "white" empire reached its maximum power and was expanding through non-"white" Africa. There must surely have been a huge expansion of slavery as they enslaved everyone that wasn't white. Except it did not happen, because by this time they had both banned slavery and were actively trying to suppress it within its territory and through treaties.