Interesting tidbit... not that it really makes much difference. Still ridiculous that America has a Holocaust Memorial and not a Slave Memorial.

Time for an historic fact that no one wants to own: It was a black man's insistence that he owned another man that resulted in slavery in the US. Slavery was an African tradition - it did not exist in England or the Colonies. Blacks brought to the colonies as indentured servants had been slaves in Africa. They had been conquered in tribal wars or had unpaid debts or had been sold by their parents. Europeans traded rum, spice and other goods with the tribal chiefs in exchange. Once in the colonies they were indentured servants just like their English counterparts and would be freed once their contract period was up.
Anthony Johnson arrived in Jamestown in 1621 as an indentured servant from Angola - where he had been a slave. At the end of his contract he was freed and was given land. One of his indentured servants was a man named John Casor. Expecting to be released from his indenture, Casor arranged to work for a white neighbor, Robert Parker. Anthony Johnson went to court claiming that Casor was not a servant but a slave, owned for life. The court ruled in Johnson's favor.
On 8 March 1655, John Casor of Virginia, a former 'indentured servant' of Virginia, became the first person to be legally declared a slave for life.  Link