The peace of Augsburg (1555) had been expected to settle the religious question in the Germanies. But in practice it had failed to fix two important matters. In the first place, the provision forbidding further secularization of church property ("Ecclesiastical Reservation") was not carried out, nor could it be while human nature and human temptation remained. Every Catholic ecclesiastic who became Protestant would naturally endeavor to take his church lands with him. Then, in the second place, the peace had recognized only Catholics and Lutherans: meanwhile the Calvinists had increased their numbers, especially in southern and central Germany and in Bohemia, and demanded equal rights. In order to extort concessions from the emperor, a union of Protestant princes was formed, containing among its members the zealous young Calvinist prince of the Palatinate, Frederick, commonly called the Elector Palatine of the Rhine. The Catholics were in an equally belligerent frame of mind. Not only were they determined to prevent further secularization of church property, but, emboldened by the progress of the Catholic Reformation in the Germanies during the second half of the sixteenth century, they were now anxious to revise the earlier religious settlement in their own interest and to regain, if possible, the lands that had been lost by the Church to the Protestants. The Catholics relied for political and military support upon the Catholic Habsburg emperor and upon Maximilian, duke of Bavaria and head of the Catholic League of Princes. Religiously, the enemies of the Habsburgs were the German Protestants.
[Sidenote: The Thirty Years' War: Political Causes]
But a hardly less important cause of the Thirty Years' War lay in the politics of the Holy Roman Empire. The German princes had greatly increased their territories and their wealth during the Protestant Revolution. They aspired, each and all, to complete sovereignty. They would rid themselves of the outworn bonds of a medieval empire and assume their proper place among the independent and autocratic rulers of Europe. On his side, the emperor was insistent upon strengthening his position and securing a united powerful Germany under his personal control. Politically, the enemies of the Habsburgs were the German princes.
With the princes was almost invariably allied any European monarch who had anything to gain from dividing Germany or weakening Habsburg influence. In case of a civil war, the Habsburgs might reasonably expect to find enemies in Denmark, Sweden, and France.
[Sidenote: Four Periods in the Thirty Years' War]
The war naturally divides itself into four periods: (1) The Bohemian Revolt; (2) The Danish Period; (3) The Swedish Period; (4) The French or International Period.
[Sidenote: 1. The Bohemian Revolt]
The signal for the outbreak of hostilities in the Germanics was given by a rebellion in Bohemia against the Habsburgs. Following the death of Rudolph II (1576-1612), a narrow-minded, art-loving, and unbalanced recluse, his childless brother Matthias (1612-1619) had desired to secure the succession of a cousin, Ferdinand II (1619-1637), who, although a man of blameless life and resolute character, was known to be devoted to the cause of absolutism and fanatically loyal to the Catholic Church. Little opposition to this settlement was encountered in the various Habsburg Bohemian dominions, except in Bohemia. In that country, however, the nobles, many of whom were Calvinists, dreaded the prospective accession of Ferdinand, who would be likely to deprive them of their special privileges and to impede, if not to forbid, the exercise of the Protestant religion in their territories. Already there had been encroachments on their religious liberty.
One day in 1618, a group of Bohemian noblemen broke into the room where the imperial envoys were stopping and hurled them out of a window into a castle moat some sixty feet below. This so-called "defenestration" of Ferdinand's representatives was followed by the proclamation of the dethronement of the Habsburgs in Bohemia and the election to the kingship of Frederick, the Calvinistic Elector Palatine. Frederick was crowned at Prague and prepared to defend his new lands. Ferdinand II, raising a large army in his other possessions, and receiving assistance from Maximilian of Bavaria and the Catholic League as well as from Tuscany and the Spanish Habsburgs, intrusted the allied forces to an able veteran general, Count Tilly (1559-1632). King Frederick had expected support from his father-in-law, James I of England, and from the Lutheran princes of northern Germany, but in both respects he was disappointed. What with parliamentary quarrels at home and a curiously mistaken foreign policy of a Spanish alliance, James confined his assistance to pompous advice and long words. Then, too, most of the Lutheran princes, led by the tactful John George, elector of Saxony, hoped by remaining neutral to obtain special concessions from the emperor.
Within a very brief period, Tilly subdued Bohemia, drove out Frederick, and reestablished the Habsburg power. Many rebellious nobles lost their property and lives, and the practice of the Protestant religion was again forbidden in Bohemia. Nor was that all. The victorious imperialists drove the fugitive Frederick, now derisively dubbed the "winter king," out of his original wealthy possessions on the Rhine, into miserable exile, an outcast without land or money. The conquered Palatinate was turned over to Maximilian of Bavaria, who was further rewarded for his services by being recognized as an elector of the Holy Roman Empire in place of the deposed Frederick.