From 1530, when the League of Schmalkald was formed to unite the Protestant princes and cities, Germany really belonged to two camps, and civil war was only a question of time. The time came in 1546, the year of Luther's death, when Charles was at last free from foreign complications and could make the attempt to reintroduce conformity into Germany. The Schmalkaldic War, although marked by a series of imperial successes and temporarily closed by a triumphant truce in 1548, was soon renewed, and the Peace of Passau of 1552 was a general compromise, representing rather the weariness of war and the jealousies of the various powers of Germany than any permanent political of religious equilibrium. An attempt was made to establish a more lasting settlement in the conference of Augsburg in 1555. Here the terms of the recent treaty were put in more formal shape: Lutheranism was given legal recognition; all religious disputes should be settled by peaceful means; in legal causes between a Protestant and a Catholic the Imperial Hight Court of Justice should be composed of an equal number of Catholics and Protestants.
On the other hand, certain compromises were then introduced which were destined to be fatal to the permanency of the religious and political settlement.
1. Instead of individual toleration, as was originally proposed, the principle was adopted which has become known as cujus regio ejus religio—that is to say, each prince or imperial city should choose between Catholicism and Lutheranism; and thereafter all inhabitants must conform, or, if unwilling to do so, must expatriate themselves. The unstable equilibrium of the empire was thus transferred to the individual states, and each was threatened with internal revolution whenever there was a change in the prevailing religious views of the inhabitants or the personal beliefs of the prince.
2. A second compromise was reached by providing that all ecclesiastical property seized by temporal governments down to the close of the late war should be guaranteed to its new possessors; but that for the future the process of secularization should cease. Thus an artificial obstacle was placed in the way of the avarice or the desire for reform of the Protestant princes, at the very time they were given increased control in their own states.
3. The "ecclesiastical reservation" made an exception to the right of territorial independence in religion in the case of the ecclesiastical states, which were so numerous in Germany. If any archbishop, bishop, or abbot, who was also a secular prince, should become a Lutheran, he must resign his office and divest himself of his power and jurisdiction, which would pass to his Catholic successor. This provision deprived Protestant subjects of ecclesiastical princes of all prospect of religious freedom, and doomed them to compulsory reconciliation with the Catholic Church or to exile, except for certain rights guaranteed to them by the treaty.
4. The compromises of Augsburg were compromises between Catholics and Lutherans only, and neither Calvinists nor Zwinglians were given recognition in its terms, although Calvinism was destined to be the great aggressive force of the Reformation, making an appeal to the masses of the people and taking a fundamental hold upon its adherents beyond anything which Lutheranism, or indeed any other form of the Reformation, ever obtained.
The agreement reached in 1555, incomplete and unstable as it seemed, remained the foundation of an outward if somewhat troubled religious peace for more than sixty years. Yet a renewal of the conflict was threatened from time to time, and in 1618 the terrible Thirty Years' War broke out. The earlier contests had been civil wars only, the renewed war was no longer merely a German struggle. In 1625 Christian IV., king of Denmark, entered the war as leader on the Protestant side, only to yield to the perseverance of Tilly, the general of the Catholic armies, and to the genius of Wallenstein, the representative of Emperor Ferdinand; and to retire in 1629, leaving north Germany more completely than before at the mercy of the emperor and of the Catholic party. Scarcely a year later Gustavus Adolphus, full of enthusiasm for the Protestant cause and provided with funds from France, brought his veteran regiments and his military ability from Sweden into Germany, and fought in consecutive years his three wonderful campaigns. After the death of the "Lion of the North," in 1632, the "Swedish period" endured still two years; and when, in 1634, Catholic and Protestant princes entered upon a truce they made terms upon an equality, though there was even yet but little promise of a permanent settlement.
Just before the fatal battle of Lutzen, in the midst of military preparations, a decisive step was taken by Gustavus which ultimately led to the creation of one more American colony. Ever since the introduction of new issues. One after another, foreign states were drawn into the struggle until a mere German civil war had developed into a general European conflict, in which foreigners were struggling for German territory. Catholics made alliances with Lutherans and with Calvinists, until what had begun as a religious struggle became a purely political contest among unpatriotic German princes and ambitious neighbors of Germany contending for power and prestige.
When, at the peace of 1648, political questions had been settled, territorial changes agreed upon, the Netherlands and Switzerland definitely separated from the empire, Alsace surrendered to France, and much of Pomerania to Sweden, the religious conflict was brought to an end as far as possible by returning to the old plan of the treaty of Augsburg, except that such toleration as was then granted to Catholics and Lutherans was now extended to Calvinists also. To these provisions some further extensions of religious liberty were added by securing guarantees of protection to subjects differing in their religion from their princes and by including in the highest imperial tribunal a certain number of Protestants. [Footnote: Lamprecht, Deutsche Geschichte, V., sect ii., 764.] The material sufferings and losses of Germany during the war were almost beyond description. [Footnote: Erdmannsdorffer, Deutsche Geschichte, 1648-1740, I., 100-115] The armies, made tip largely of soldiers of different nationalities, without attachment to the countries through which they marched, without interest in the questions at issue, without a regular commissariat, often without pay, brutalized by long campaigning and repeated sacks of cities, followed by an immense rabble of non-combatant men, women, and children, were a barbarian horde, and ravaged the lands in which they were established like a fire or a pestilence. The tortures they inflicted upon the peasantry and the citizens, the robbery, the outrages, the wanton destruction, pressed close to the limits of human endurance, and seemed almost to threaten the extermination of the population. The prosperity of the cities was crushed by war contributions, even when they escaped being plundered like Magdeburg; and the debasement of the coinage practised by the emperor and the princes bore hardly upon all who bought or sold. [Footnote: Gindeley, History of the Thirty Years' War (English trans.), II., 390-395] During the later campaigns of the war military operations in many regions became almost impracticable from the very impoverishment of the country; no sustenance existed for friend or for enemy; population in some parts was almost destroyed, and it was everywhere extensively displaced. [Footnote: Ibid., 398.] The conservatism, the settled rooting of the people in the soil, acquired and inherited property, moral and material fixity, were all alike disturbed.
The half-century that followed 1648 did but little to restore prosperity or repose to Germany. The western provinces especially were the scene of frequently renewed warfare. The territorial ambitions of Louis XIV. were directed to the German lands which lay on the eastern border of France, and there was no strength in the empire to resist his aggressions or to make him fear either defeat or reprisals. Even the European coalitions which forced upon him successive treaties did not prevent renewed attacks or heal the scars of the repeated devastations of the lower and the upper Rhine country. The culmination of this period of suffering was the terrible ravaging of the Palatinate, in 1688, when the fertile region about Heidelberg, Mannheim, Speyer, and Worms was harried and burned and pillaged by the soldiers of Louis, with the same brutality and more destructiveness than the wild Swedish and mercenary armies of the Thirty Years' War had used.