The Armada of 1779 was an attempted Franco-Spanish invasion of the British Isles that occurred in 1779 amid the American Revolutionary War. The allies planned to seize the Isle of Wight and then the British naval base of Portsmouth, but no fleet battles were fought and the invasion never occurred.
Following the 1778 First Battle of Ushant, the French signed a secret treaty with Spain on 12 April 1779, bringing Spain into the war against Great Britain and enabling the French Navy and Spanish Navy to join forces for an invasion of Britain. The two fleets were to meet off Corunna in northwest Spain, with Admiral Louis Guillouet d'Orvilliers leading 30 French ships of the line to meet with the Spanish. However, the Spanish fleet was absent due to contrary winds, forcing d'Orvilliers to suspend the invasion. The French crews were weakened by scurvy, typhus, and smallpox while awaiting the Spaniards, who finally arrived on 22 July with 36 ships of the line. 40,000 French troops assembled at Le Havre and St. Malo in northern France, and they were to wait until the French and Spanish put the Royal Navy out of action so that the allied army could be safely transported across the English Channel and set up a base on either the Isle of Wight or the nearby British coast. Sir Charles Hardy had fewer than 40 ships of the line available in the Channel. However, the Franco-Spanish armada was delayed by contrary winds, and the French sailors' diseases soon spread to the Spanish troops. The armada missed out on two British merchant convoys and finally passed Ushant on 11 August, reaching the Channel shortly after. The British fleet had moved to the Isles of Scilly after hearing that the French fleet had gone out to the Atlantic, and the English coast experienced a wave of alarm as the allied fleet approached. The French government ordered the armada to turn around and land at Falmouth in Cornwall instead of southern England, but D'Orvilliers halted the fleet as he asked the government to reconsider. The fleet was driven far to the west and out into the Atlantic by an 18 August gale, and they came up against Hardy's fleet. Hardy lured the Franco-Spanish fleet towards Portsmouth and the well-defended Solent, and the French and Spanish, already devastated by disease, ultimately decided to abandon their campaign and set sail for Brest.
In the aftermath of the failed invasion, the British hastily improved their coastal defenses. The expedition was a costly failure for France, as keeping so many ships at sea and so many troops waiting at embarkation ports for months on end was expensive both in money and lives. D'Orvilliers resigned his post shortly after returning to France.