The ideals of the Enlightenment that fueled the American Revolution, i.e. that "all men are created equal" were, sadly, just that -- ideals. They were lofty ideals on the part of the founding fathers, many of whom were slaveholders themselves and had no intention of freeing their slaves. In the beginning of the war, African-Americans played an important role in joining the fighting against the British. Crispus Attucks, a black man, was one of the ones killed in the infamous "Boston Massacre." Soon, however, blacks were forbidden from joining the army and even General Washington himself banned blacks from joining up. After his army started deserting in great numbers, however (after Valley Forge), he had to rethink his position. In the meantime, the British promised freedom to any African-Americans who would fight for their side, so many Blacks joined the British Army. Escaped slaves joined the British and were fierce fighters because they were fighting for their freedom from their white masters.
The American Revolution did not solve the slavery problem for African-Americans because in the interest of forming a government and appeasing the slaveholding states, the founding fathers did not abolish slavery as part of the new Constitution. This would become a continuing unresolved issue until the Civil War because as new states were added to the Union, the question of balance always popped up -- would the new state be free or slave? The ideals of the American Revolution were not all in vain, however, because many northern states individually abolished slavery on their own believing that it was against God and against the principles on which the country was founded. Slavery was so connected to the economy in the South, however, that the southern states resisted, citing states rights, and eventually seceded from the Union, causing the Civil War. Many historians believe the Civil War was caused by regional issues, slavery among them, that were never properly resolved by the Declaration of Independence and early Constitution.