It would be in "D. Haiti" that slavery ended with revolution than by government decree, since this was the result of a massive slave uprising that ended up ultimately being successful.
Roundheads were Parliamentary/Puritan soldiers who wore tight fitting un-orimented metal helmets, while Cavaliers were kings men who wore large hats with feathers as their uniform headdress.
Some differences between the round-heads and the cavaliers are that the cavaliers supported the King and the round-heads supported Parliament.
