During the 17th century, Alsace was one of the main battlefields of the Thirty Years War. Sélestat was seized by the Swedes in 1632 after a month-long siege. They surrendered the town to their French allies two years later. The local population long remained predominantly faithful to the House of Habsburg. The Peace of Westphalia (1648) formalised the annexation of the Decapolis by France. Sélestat was briefly occupied by the Germans during the Franco-Dutch War in 1674. The Treaties of Nijmegen (1679) that ended the war also abolished the Decapolis.