During the American Revolution, why did many African-American slaves fight for the British and against the colonists? African-American slaves sided with the British because the colonists had excluded slave rights from the Declaration of Independence and the Paris Peace Treaty. African-American slaves defected to the British after their “masters” forced them to serve in separate “black” regiments in the Continental Army. The British guaranteed African-American slaves that they would be liberated if they fought on the side of the British during the Revolution. African-American slaves were banned from serving in the Continental Army across the course of the American Revolution. The British assured African-American slaves passage to Africa if they aided the British against the colonists.