It's easy to tally up the greatness of the free market when you redefinento boundaries of society to exclude the huge negative costs imposed on slaves and laborers.
Um... I agree the word "free" is misleading but once you're in a legal system that condones slavery then of course it would be a free market. I'm having a hard time imagining the slave trade arising without a market much more free than the people forced through it.
Markets are amoral. That's why we shouldn't rely on them to solve social problems.
What slaves? That was a century ago.