One of the most revolutionary social reforms of the Jacobin regime was the abolition of slavery in the French colonies. The slave trade began in the seventeenth century. French merchants sailed from the ports of Bordeaux or Nantes to the African coast, where they bought slaves from local chieftains. Branded and shackled, the slaves were packed tightly into ships for the three-month long voyage across the Atlantic to the Caribbean. There they were sold to plantation owners. The exploitation of slave labour made it possible to meet the growing demand in European markets for sugar, coffee, and indigo. Port cities like Bordeaux and Nantes owed their economic prosperity to the flourishing slave trade. Throughout the eighteenth century there was little criticism of slavery in France. The National Assembly held long debates about whether the rights of man should be extended to all French subjects including those in the colonies. But it did not pass any laws, fearing opposition from businessmen whose incomes depended on the slave trade. It was finally the Convention which in 1794 legislated to free all slaves in the French overseas possessions. This, however, turned out to be a short-term measure: ten years later, Napoleon reintroduced slavery. Plantation owners understood their freedom as including the right to enslave African Negroes in pursuit of their economic interests. Slavery was finally abolished in French colonies in 1848.