The Franco-Spanish War was a military conflict between France and Spain. It began with French intervention into the Thirty Years' War, in which Spain was already a participant, in 1635. Warfare between the two kingdoms continued until 1659, when the Treaty of the Pyrenees was signed.
During the Thirty Years' War, in which various Protestant forces battled Imperial armies, France provided subsidies to the enemies of the empire. France generously supported a Swedish invasion of the Empire after 1630. After some early successes, the Swedish army was decisively defeated in 1634 by a combined Spanish-Imperial army, leading to a peace treaty favorable to the Emperor. Unhappy with this outcome, France's First Minister, Cardinal Richelieu, decided in 1635 to actively involve his kingdom in the fighting and declared war on Spain.
During the last decade of the Thirty Years' War, the Spanish forces in the Southern Netherlands were sandwiched between French and Dutch forces. When the peace treaty was negotiated, France insisted upon Spain being excluded. In the Peace of Westphalia, France gained territory in the Alsace, thus interrupting the Spanish Road.
In Italy, France fought with the more or less reluctant support of its client state Piedmont against the Spanish in the Duchy of Milan. Confusion was added from 1639-42 by the Piedmontese Civil War. The siege of Turin in 1640 was a famous event in both this war and the Franco-Spanish conflict. France also tried to take the Tuscan Presidios in 1646, and involved itself in the Naples revolt of 1647-8.
In Spain, France fought the Spanish along the Pyrenees but mostly in Catalonia and Roussillon. In 1640, the war became merged with the Catalan Revolt, when the Catalans invited in the French to help defend them.
In 1653 France was so exhausted that neither invaders nor defenders were able to gather supplies to enable them to take the field until July. At one moment, near Péronne, Condé had Turenne at a serious disadvantage, but he could not galvanize the Spanish general Count Fuensaldana, who was more solicitous to preserve his master's soldiers than to establish Condé as mayor of the palace to the king of France, and the armies drew apart again without fighting. In 1654 the principal incident was the siege and relief of Arras. On the night of the August 24–August 25 the lines of circumvallation drawn round that place by the prince were brilliantly stormed by Turenne's army, and Condé won equal credit for his safe withdrawal of the besieging corps under cover of a series of bold cavalry charges led by himself as usual, sword in hand.
In 1655 Turenne captured the fortresses of Landrecies, Condé and St Ghislain. In 1656 the prince of Condé revenged himself for the defeat of Arras by storming Turenne's circumvallation around Valenciennes (July 16), but Turenne drew off his forces in good order. The campaign of 1657 was uneventful, and is only to be remembered because a body of 6,000 British infantry, sent by Cromwell in pursuance of his treaty of alliance with Mazarin, took part in it. The presence of the English contingent and its very definite purpose of making Dunkirk a new Calais, to be held perpetually by England, gave the next campaign a character of certainty and decision which was entirely wanting in the rest of the war.
Dunkirk was besieged promptly and in great force, and when Don Juan of Austria and Condé appeared with the relieving army from Fumes, Turenne advanced boldly to meet them. The Battle of the Dunes, fought on June 14 1658, was the first real trial of strength since the battle of the Faubourg St Antoine. The battle resulted in an Anglo-French triumph over the forces of Spain and Condé. Here the "red-coats" made their first appearance on a continental battlefield, under the leadership of Sir W. Lockhart, Cromwell's ambassador at Paris, and astonished both armies by the stubborn fierceness of their assaults, for they were the products of a civil war in which passions ran higher and the determination to win rested on deeper foundations than in the degringolade of the feudal spirit found in France. Dunkirk fell and was handed over to England, as promised. It would remain under English rule until its sale by Charles II to Louis XIV. A last desultory campaign followed in 1659 before the war ended.
In Italy, the war along the border between Piedmont and the Spanish-held Duchy of Milan continued. Twice, in 1647-9 and 1655-9, France managed to open a second front against Milan by gaining the alliance of Francesco I d'Este, Duke of Modena, but this never achieved the desired result of breaking the Spanish defence.
In Spain, the French were unable to hold Catalonia against reconquest by the Castilians; Barcelona surrendered in 1652, ending the Catalan Revolt, but Spain remained distracted by the Portuguese Restoration War, and although desultory fighting continued in both Catalonia and Roussillon, the situation stabilised with the Pyrenees as the effective border.