France ceded Louisiana to Spain in 1762, but by the secret Treaty of San Ildefonso of 1800 the French had regained the area. Napoleon Bonaparte had envisioned a great French empire in the New World. He had hoped to use the Mississippi Valley as a food and trade center to supply the island of Hispaniola, the heart of the empire. When Napoleon could not hold onto Hispaniola following the uprising of Haitian slaves, the idea of the new empire vanished. Facing another war with England, Napoleon needed money. In 1803 he offered to sell Louisiana to the United States. Concerned about French intentions, President Thomas Jefferson already had sent James Monroe and Robert R. Livingston to Paris to negotiate the purchase of a tract of land on the lower Mississippi or at least to guarantee free navigation on the river. The U.S. emissaries were surprised by the French offer and immediately negotiated the treaty. In one stroke, the United States doubled its territory.