In 1315, Louis X, king of France, published a decree proclaiming that “France signifies freedom” and that any slave setting foot on the French ground should be freed. And France maintained that law, even after it began allowing slavery in its New World colonies in the 1600s. Any enslaved person who as brought to France became free. Born into slavery in Saint Domingue, Thomas-Alexandre Dumas became free when his father brought him to France in 1776.
Slavery in the French colonies was another story. The French crown regulated the slave trade and institution in the colonies, starting with Louis XIV’s Code Noir in 1685. The royal government had over 100 years of profiting from plantation-based slavery and particularly sugar production before the French Revolution killed the royal family and attempted to end slavery in the colonies. The first elected Assembly of the First Republic abolished slavery in France (since the royal law was no longer recognized) and more importantly in France’s colonies.
However, Napoleon restored slavery and the slave trade in 1802. This was mainly because of lobbying by planters in the West Indies, and to benefit from taxing the planter’s slavery-produced profits. In 1848, under the Second Republic, slavery was totally abolished in the French colonies. And this time it stuck.