Beginning as early as the 17th century, some planters freed individual slaves by manumission. Some free mixed-race families, established before the American Revolution, were formed by descendants of unions or marriages between white indentured or free women and African men, indentured, slave or free. Colonial law and the principle of "partus sequitur ventrem," provided that children were born into the status of their mother. Thus, the mixed-race children of white women were born free. If illegitimate, they had to serve time in lengthy apprenticeships, but freedom gave them an important step forward.