But Europe's is the only civilization in the whole of history that voluntarily abolished chattel slavery.

FORBES: A chat with J.M. Roberts

So was chattel slavery and the back-breaking manual labor that kept these massive plantations thriving.

CNN: Django, in chains

Anti-Slavery International's Beth Herzfeld told the BBC earlier this year that chattel slavery, involving a class of hereditary slaves, still existed in parts of Africa, and bonded labour remained common in South Asia.

BBC: Undated depiction of slaves in captivity