The brief peace in Europe allowed Napoleon to focus on the French colonies abroad. Saint-Domingue had managed to acquire a high level of political autonomy during the Revolutionary Wars, with Toussaint Louverture installing himself as de facto dictator by 1801. Napoleon saw his chance to recuperate the formerly wealthy colony when he signed the Treaty of Amiens. During the Revolution, the National Convention voted to abolish slavery in February 1794. Under the terms of Amiens, however, Napoleon agreed to appease British demands by not abolishing slavery in any colonies where the 1794 decree had never been implemented. The resulting Law of 20 May never applied to colonies like Guadeloupe or Guyane, even though rogue generals and other officials used the pretext of peace as an opportunity to reinstate slavery in some of these places. The Law of 20 May officially restored the slave trade to the Caribbean colonies, not slavery itself. Napoleon sent an expedition under General Leclerc designed to reassert control over Sainte-Domingue. Although the French managed to capture Toussaint Louverture, the expedition failed when high rates of disease crippled the French army. In May 1803, the last 8000 French troops left the island and the slaves proclaimed an independent republic that they called Haïti in 1804. Seeing the failure of his colonial efforts, Napoleon decided in 1803 to sell the Louisiana Territory to the United States, instantly doubling the size of the U.S. The selling price in the Louisiana Purchase was less than three cents per acre, a total of $15 million.