Did France free Haiti's slaves, or did they free themselves?

Both, but in a particular order. The enslaved people of Saint-Domingue rose in revolt on the night of 21 August 1791, before any French law freed them. Facing military disaster, a commissioner sent by Paris, Sonthonax, offered freedom to slaves who would fight for the Republic and in August 1793 abolished slavery in the Northern Province; in February 1794 the Convention decreed abolition in all the colonies. When Napoleon later tried to bring slavery back, Haitians fought and won independence on 1 January 1804. The revolt forced French leaders to face the full meaning of their own ideals.

The scale of the colony explains the stakes. In 1789 Saint-Domingue had about 40,000 whites, 28,000 free people of colour, and an estimated 452,000 enslaved Black people. The Declaration of the Rights of Man was ambiguous about whether its equality applied to slaves or colonial citizens, which influenced the desire for freedom there. In October 1790 the free man of colour Vincent Ogé demanded the right to vote under it.

Toussaint Louverture, first allied with Spain, switched to the French when the Republican government moved to abolish slavery. In 1801 he issued a constitution naming himself governor-for-life and calling for Black autonomy and a sovereign Black state. Napoleon sent a large expeditionary force under his brother-in-law Charles Leclerc, with secret instructions to restore slavery, at least in the formerly Spanish-held part of the island. When he was overthrown, Louverture warned his captors that they had cut down only the trunk of the tree of liberty.

Black and mixed-race forces, former rivals, together defeated the French at Vertières in November 1803, and Dessalines declared independence as Haiti on 1 January 1804. The price came later: in 1825 France, with warships offshore, made Haiti pay 150 million gold francs to former slaveholders as the condition of recognising it. Reduced to 90 million in 1838, the debt took until 1947 to pay off.