Which civilized countries are those?  

The numerous countries in Africa who have been capturing slaves for centuries (most recently Al Shabab and their ilk) and who use to sell  them to the British, the Portugese, the Spanish the Dutch and whoever else showed up?

Those 'civilized' countries?  Or the buyers of the slaves? 

And Britain supported the South during the Civil War despite having 'abolished' slavery prior to that time.  

When did they get 'civilized'?

 It certainly wasn't in 1807 or in 1833 when they were supporting the slave holding States of the Confederate States of America.   


And they invented the three-way trade clear back in the 1500's.