Sally Hemings was one of Thomas Jefferson's slaves and, for many years, his mistress. Sexual relations between white slave-owners and their slaves were quite common in those days; although the men who engaged in such behavior were expected to be discreet about it. When Jefferson was appointed as the American envoy to France, he took Sally with him, along with her older brother, James. As slavery had been abolished in France after the Revolution, Sally and James were entitled to petition for their freedom. Yet they chose not to do so and continued to work for Jefferson, only now they were paid a servant's wage, as slavery was no longer permitted on French soil.
Sally could've chosen to remain in France. Had she done so, she would've been a free woman. But she chose to accompany Jefferson back to Virginia, even though she knew full well that she would become a slave once more as soon as she set foot on American soil. So why did she choose to go back? There are two main reasons. First of all, Sally had very strong family ties and couldn't bear to be apart from her mother and her siblings at Monticello. Secondly, Jefferson promised that Sally's children would all be freed when they came of age (i.e., when they reached the age of 21). Though Sally lived the rest of her life as a slave, all of her children who survived into adulthood were freed by Jefferson, who made good on his promise.