Albert J. Raboteau acknowledges some of the earliest opponents of American slavery.
Yes, Quakers were among the early opponents of slavery. Benjamin [sic: John] Woolman actually went to the South and tried to convince some of his fellow Quakers in the South that holding slaves was wrong. And he actually would try to sneak some money to the slaves on the side if he could. So the Quaker witness against slavery goes back to the very early days, and blacks were very appreciative of that.