Alsace, except the city of Mulhouse, was annexed to France in the course of the reign of Louis XIV. The Middle Ages had broken the country up into a great variety of feudal states and free cities; the Reformation divided it still further by religious dissensions. In the Thirty Years’ War France intervened on the side of the Protestant princes of Germany; at its close France received considerable possessions in Alsace, in much the same way that Brandenburg (the future Prussia) then secured valuable additions in the north. The treaty of Westphalia (1648) assured to France certain lands and certain governmental rights possessed by the Emperor in his imperial capacity and as head of the house of Hapsburg, but the provisions were, possibly with intention, left vague at certain points and became the occasion of protracted legal and historical disputes. By a combination of undoubted grants, more or less justified legal interpretations, and the direct seizure of the city of Strasburg, Louis XIV rounded out his possession of the whole of Alsace. The sole exception, Mulhouse, allied with the Swiss Confederation, voluntarily offered itself to France in 1798. Thus united to France, Alsace and Lorraine retained their boundaries until the treaty of Vienna. The general principle of the territorial adjustments of 1814 was to leave to France its frontiers of 1792; after Napoleon’s return and defeat at Waterloo the treaty of 1815 was supposed to reduce these to the limits of 1789. In Alsace and Lorraine two deviations were made from this principle, both to the disadvantage of France. At the northern end of Alsace France lost to Bavaria the territory between the Lauter and the Queich, including the fortress of Landau which she had possessed in 1789. On the northern border of Lorraine the frontier was readjusted to the advantage of Prussia, partly for strategic reasons, in connection particularly with the fortress of Saarlouis, partly in order to take away from France the valuable coal deposits of the Saar valley. At the close of the Franco-Prussian war Germany required of France the cession of Alsace and Lorraine, with a boundary on the west which was defined by the treaty of Frankfort in 1871. In the next forty years Alsace-Lorraine passed through various stages of government, from military dictatorship through a certain amount of territorial independence to the definite constitution imposed by the Reichstag in 1911. Those who had hoped for autonomy were disappointed in this instrument, which failed to elevate the Reichsland to the position of a federated state of the empire, although an anomalous provision was made for its representation in the Bundesrat. Legally Alsace-Lorraine was still a subject territory of the empire.