During the American Revolution, most of the slaves could not serve in the army, free blacks could but slaves could not. Some historians say that the American Revolution reinforced the idea of a racial identity based on skin color.
Because of that some slaves and blacks decided to fight for the British, because they offered them freedom for joining their cause, a thing that the Americans did not offer them.
Of the half a million slaves that were in the American colonies during the American Revolution, 20 thousand joined the British cause. Many slaves that belonged to George Washington, Thomas Jefferson, Patrick Henry, and others fled to the British side.
The main result was that this led to the largest slave uprising and the greatest emancipation until the Civil War. Some of those ex-slaves emigrated to Sierra Leone, Canada, and Britain.
