You sure you aren’t thinking of Liberia?
Per Wikipedia, the Brits sent slaves they freed from illegal slave ships, as well as blacks from America who fought on their side during the American Revolution, as well as blacks from various other places, Canada, London, etc.
You sure you aren’t thinking of Liberia?
Check it out on wikipedia. Liberia may have been as well. I know about Sierra Leone as I have a friend from there. She is very proud to be descended from one of those freed slaves who settled the country.