By the 18th century, Britain had become the largest exporter of African slaves. However, Britain would be the first major European country to outlaw the slave trade in 1807. There were both social and economic reasons for Britain's change. Socially, reform movements challenged slavery. Economically, slavery became less profitable as sugar production costs decreased in other colonies and the price of slaves increased. Britain also began to industrialize and favor wage labor over slave labor in factories.