As restrictions on colonial trade were relaxed, the colonial elites of St. Domingue offered the principal market for Santo Domingo's exports of beef, hides, mahogany, and tobacco. With the outbreak of the Haitian Revolution in 1791, the rich urban families linked to the colonial bureaucracy fled the island, while most of the rural "hateros" (cattle ranchers) remained, even though they lost their principal market. Although the population of Spanish Santo Domingo was perhaps one-fourth that of French Saint-Domingue, this did not prevent the Spanish king from launching an invasion of the French side of the island in 1793, attempting to take advantage of the chaos sparked by the French Revolution. French forces checked Spanish progress toward Port-au-Prince in the south, but the Spanish pushed rapidly through the north, most of which they occupied by 1794. Although the Spanish military effort went well on Hispaniola, it did not in Europe (see War of the Pyrenees). As a consequence, Spain was forced to cede Santo Domingo to the French under the terms of the Treaty of Basel (July 22, 1795) in order to get the French to withdraw from Spain.