In 1799, Spain gave Louisiana back to France in exchange for the promise of a throne in central Italy. Although the agreement was signed on October 1, 1800, it did not go into effect until 1802. The following year, Napoleon sold Louisiana to the United States. The original agreement between Spain and France had not explicitly specified the borders of Louisiana, and the descriptions in the documents were ambiguous and contradictory. The United States insisted that its purchase also included most of West Florida and all of Texas.