Napoleon sent an expedition under his brother-in-law General Leclerc to reassert control over Saint-Domingue. Although the French managed to capture Toussaint Louverture, the expedition failed when high rates of disease crippled the French army, and Jean-Jacques Dessalines won a string of victories, first against Leclerc, and when he died from yellow fever, then against Donatien-Marie-Joseph de Vimeur, vicomte de Rochambeau, whom Napoleon sent to relieve Leclerc with another 20,000 men. In May 1803, Napoleon acknowledged defeat, and the last 8,000 French troops left the island and the slaves proclaimed an independent republic that they called Haiti in 1804. In the process, Dessalines became arguably the most successful military commander in the struggle against Napoleonic France. Seeing the failure of his efforts in Haiti, 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.