There were two Treaties of Aix-la-Chapelle. The first was in 1668, ending the War of Devolution; the second was in 1748, ending the War of Austrian Succession. These are sometimes known as Treaties of Aachen, since, "Aix-la-Chapelle" is the French name for the city of Aachen.
In the First Treaty of Aix-la-Chapelle France gained control of Lille, from Spain, and returned the Franche-Comté, to Spain.
A congress assembled at Aix-la-Chapelle on April 24, 1748 with the intent to conclude the struggle known as the War of Austrian Succession. The resulting treaty, the Treaty of Aix-la-Chapelle, signed on October 18, 1748, ended that war.
- a general restitution of conquests, including The Louisbourg fortress on Cape Breton Island, Nova Scotia to France, Madras, India to England and the barrier towns to the Dutch.
- The treatly also awarded Austrian lands to Habsburg heiress Maria Theresa, but she had to give up the duchies of Parma, Piacenza and Guastalla to Don Philip of Spain.
- The restoration of the duke of Modena and the republic of Genoa to their former positions.
- The renewal in favour of Great Britain of the Asiento contract of the March 16, 1713, and of the right to send an annual vessel to the Spanish colonies.
- The guarantee to Kingdom of Prussia of the duchy of Silesia and the county of Glatz.
Spain later raised objections to the Asiento clauses, and the later Treaty of Madrid supplemented the treaty of Aix-la-Chapelle on October 5, 1750. The Treaty of Madrid stipulated that Great Britain surrendered her claims under the Asiento clauses in return for a sum of £100,000.