Abolitionists in Europe and Americas protested the inhumane treatment of African slaves, which led to the elimination of the slave trade (and later, of most forms of slavery) by the late 19th century. One (disputed) school of thought points to the role of abolitionism in the American Revolution: while the British colonial metropole started to move towards outlawing slavery, slave-owning elites in the Thirteen Colonies saw this as one of the reasons to fight for their post-colonial independence and for the right to develop and continue a largely slave-based economy.