The French came to Saint Domingue and started slavery. So the enslaves rebelled and started the Haitian Revolution
Adams
The rebels burned down sugar plantations
Jefferson
They killed many whites aswell
Outcome
Adams never owned slaves and thought the institution was immoral. He was more interested in maintaining trade and reducing the threat of piracy by Haitian rebels.
Under Jefferson's administration, aid to the Haitian rebels was cut off. When Haiti declared independence in 1804, the U.S. government refused to acknowledge its sovereignty.
Free black leaders referenced the revolution in their demands for equal rights. The number of organized slave rebellions in the U.S. also increased after Haiti gained independence.