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By 1820, Charleston's population had grown to 23,000, maintaining its black (and mostly slave) majority. When a massive slave revolt planned by Denmark Vesey, a free black, was revealed in May 1822, whites reacted with intense fear, as they were well aware of the violent retribution of slaves against whites during the Haitian Revolution. Soon after, Vesey was tried and executed, hanged in early July with five slaves. Another 28 slaves were later hanged. Later, the state legislature passed laws requiring individual legislative approval for manumission (the freeing of a slave) and regulating activities of free blacks and slaves.

What revolution made whites fearful of retribution of slaves?
Haitian Revolution