The Battle of Trafalgar was a fleet action which took place on 21 October 1805 between the Royal Navy and a combined fleet of the French and Spanish navies during the War of the Third Coalition. As part of Napoleon's planned invasion of the United Kingdom, the French and Spanish navies planned to take control of the English Channel and provide the French invasion army with safe passage to Britain. The allied fleet, under the command of French Vice-Admiral Pierre-Charles Villeneuve, sailed from the port of Cádiz in southern Spain on 18 October 1805. It encountered a British fleet under Vice-Admiral Horatio Nelson in the Atlantic Ocean along the southwest coast of Spain off Cape Trafalgar.