The Treaty of Aix-la-Chapelle or Aachen ended the War of Devolution between France and Spain. It was signed on 2 May 1668 in Aachen (French: Aix-la-Chapelle). Spain acceded on 7 May 1669.
The treaty was mediated and guaranteed by the Triple Alliance of England, the Dutch Republic and Sweden at the First Congress of Aix-la-Chapelle. France was forced to abandon its war against the Spanish Netherlands. Louis XIV returned three cities, Cambrai (Kamerijk), Aire (Ariën aan de Leie), and Saint-Omer (Sint-Omaars) to Spain. Louis XIV also had to return the province of Franche-Comté. Louis XIV was however allowed to keep Armentières (Armentiers), Bergues (Sint-Winoksbergen), Charleroi, Courtrai (Kortrijk), Douai (Dowaai), Furnes (Veurne), Lille (Rijsel), Oudenarde (Oudenaarde, Audenarde), and Tournai (Doornik).
The treaty left to France all its conquests in Flanders in 1667. This was a vague provision; after the Peace of Nijmegen (1679), Louis XIV took advantage of it to occupy a number of villages and towns he adjudged to be dependencies of the cities and territories acquired in 1668.