Many members of the revolutionary generation recognized the conflict between their ideology of natural rights and human equality and the practice of holding people in bondage. At the time of the war for independence, 95 percent of the African Americans in the United States were slaves. These slaves made up 20 percent of the total American population. In the south their percentage of the population was much higher; slaves were even in the majority in some parts of the south. The leaders of the United States could not ignore the practice of slavery, and they wrestled with the moral challenge slavery posed for them.

The war offered some slaves a chance for freedom. Hoping to weaken the American rebels, the British offered freedom to runaway slaves. Many slaves took advantage of the presence of British troops to escape their servitude. As many as a third of the slaves in South Carolina fled to the British. When Cornwallis surrendered at Yorktown, he had thousands of refugee slaves with him. They were tracked down by the American troops and sent back to their masters. Washington found two of his own slaves and returned them to Mount Vernon. Those slaves who successfully made their way to the British lines were sometimes sold into slavery in the West Indies, but many eventually settled in Canada as free men and women.

Another avenue to freedom was service in the American military. Early in the war, there was some reluctance to arm African Americans. General Philip Schuyler questioned the propriety of asking “the Sons of Freedom to trust their all to be defended by slaves.” Southerners were adamantly opposed to the enlistment of African Americans.

Resistance to recruiting slaves eroded as the war went on and it became harder to find recruits for the Continental army. Massachusetts accepted African American enlistments in 1777. Rhode Island did the same in 1778. The other New England States followed their example. Maryland became the only southern state to recruit slaves. Virginia accepted free African Americans into the ranks. Typically slaves served as substitutes for their masters and were guaranteed their freedom. Many free African Americans joined the military out of conviction.

Altogether, about 5,000 African Americans fought for the United States. They served in integrated units, something that would not be seen again in the American military until the Korean War. When Rochambeau's force united with Washington's troops outside New York City in 1781, the French were impressed by the number of African Americans in the ranks of the Continental army.

The contradiction involved in fighting for human liberty while countenancing slavery was obvious to many in the revolutionary period. Literate African Americans made an eloquent case for emancipation, making reference to the ideals that inspired the war. One anonymous man published as “Vox Africanorum” wrote, “Liberty is our claim. Reverence for our Great Creator, principles of humanity and the dictates of common sense, all convince us, that we have an indubitable right to liberty…. Though our bodies differ in color from yours; yet our souls are similar in a desire for freedom. Disparity in colour, we conceive, can never constitute a disparity in rights.” Connecticut slaves, petitioning the state for freedom in 1779, asked simply “Whether it is consistent with the present claims of the United States to hold so many Thousands of the Race of Adam, our Common Father, in perpetual slavery?”

The American Revolution set the northern states on the road to abolition. A group of Quakers in Philadelphia organized an antislavery society in 1775. In 1780, Pennsylvania began the process of emancipating the slaves within its borders. The next year, a court in Massachusetts found slavery incompatible with the new state constitution and declared it abolished. In 1784, New Hampshire also ended slavery, while Connecticut and Rhode Island instituted programs for the gradual emancipation of their slaves.

American leaders were often torn between their consciences and self-interest on the issue of slavery. Thomas Jefferson wrote, “Indeed I tremble for my country when I reflect that God is just; that his justice cannot sleep forever.” There was a growing sense that slavery was an evil. A downturn in the market for tobacco led some to assert that slavery would slowly fade away.

During the 1780s, slavery was prohibited in the Northwest Territories, and a date would be set for ending the importation of slaves. No one in the revolutionary generation could predict the stunning economic impact of the cotton gin, and a renewed commitment to the “peculiar institution” by the South that would result in the American Civil War.