The Battle of San Juan de Ulúa was a battle between English privateers and Spanish forces at San Juan de Ulúa (modern Veracruz, Mexico). It marked the end of the campaign carried out by an English flotilla of six ships that had systematically conducted what the Spanish considered to be illegal trade in the Caribbean Sea, including the slave trade, at times imposing it by force. Naval Battles, Ancient and Modern by Edward Shippen, 1883 (cropped and cleaned).