They felt that we were oppressing the indigenious peoples of conquered lands (which we were).
Most black soldiers were scattered throughout the Continental Army in integrated infantry regiments, where they were often assigned to support roles as wagoners, cooks, waiters or artisans. African Americans also served as gunners, sailors on privateers and in the Continental Navy during the Revolution.
African-Americans fought for both sides, providing manpower to both the British and the revolutionaries.
All amendments are important because they all function USA somehow and don't create too many problems throughout the country