Maximilian’s successor as Holy Roman emperor and as archduke of Austria, his son Rudolf II (reigned 1576–1612), had been educated in Spain strictly in the Catholic faith. He had all Protestants dismissed from court service. The conversion of the cities and market centres of Lower Austria to Catholicism was conducted by Melchior Klesl, at that time administrator of the Vienna see but later to become bishop and cardinal. In Upper Austria, where the Protestants had their strongest hold, the situation remained undecided, with the Catholic governor Hans Jakob Löbl of Greinburg and the Calvinist Georg Erasmus of Tschernembl leading the opposing religious parties. When the future emperor Ferdinand II (the son of Charles, the ruler of Inner Austria) took over in Steiermark, he proved to be the most resolute advocate of the Counter-Reformation. It was he who eventually succeeded in uprooting Protestantism, first in Inner Austria and then in the other Habsburg countries, with the exception of Hungary and Silesia.
From local skirmishes along the frontier, a long drawn-out war with the Turks developed (1592–1606). In 1598 Raab (now Győr, Hungary), which served as a bastion of Vienna, was temporarily lost; Gran, Veszprém (now in Hungary), and Stuhlweissenburg (now Székesfehérvár, Hungary) passed several times from one side to the other. The introduction of the Counter-Reformation in Hungary, moreover, resulted in a rising of Protestant elements under István Bocskay. But in 1606 at Vienna, a peace was concluded between Austria and the Hungarian estates. At Zsitvatorok another peace was negotiated with the Turks, who for the first time recognized Austria and the emperor as an equal partner.
Political disagreements between Emperor Rudolf, who, to an increasing degree, showed signs of mental derangement, and the rest of the family led to the so-called Habsburg Brothers Conflict. Cardinal Klesl in 1607 brought about an agreement between the younger relatives of the emperor to recognize his brother Matthias as the head of the family. As the conflicts with Rudolf persisted, Matthias strove to come to an understanding with the estates, which were mainly Protestant. The formation of opposing religious leagues in Germany, the Protestant Union and the Catholic League, added to the general confusion.
Matthias advanced into Bohemia, and, in the Treaty of Lieben (1608), Rudolf conceded to him the rule of Hungary, the Austrian Danube countries, and Moravia, while Matthias had to give up the Tirol and the Vorlande to the emperor. In 1609 the estates received a confirmation of the concessions that Maximilian II had made to them. The cities were guaranteed only in general terms that their old privileges should not be interfered with. At the same time, Rudolf II was forced to grant to Bohemia the so-called Letter of Majesty, which contained far-reaching concessions to the Protestants. After a final defeat of Rudolf in Bohemia in 1611, Matthias was crowned king of Bohemia. Rudolf’s death in 1612 finally ended the conflict.
After Matthias had been elected emperor, his principal councillor, Cardinal Klesl, tried in vain to arrange an agreement with the Protestants in Germany. The ensuing years were filled with wars in Transylvania, where Gábor Bethlen came to power. In the Peace of Tyrnau (1615) the emperor had to recognize Bethlen as prince of Transylvania, and, in the same year, he extended the truce with the Turks for another 25 years. In the meantime, war had broken out with Venice (1615–17) because of the pirating activities of Serb refugees (Uskoken) established on the Croatian coast. A settlement was reached in the Peace of Madrid. The situation in Bohemia then reached a critical point, the religious tensions in the country finding a vent in the Defenestration of Prague (May 23, 1618), in which two of the emperor’s regents were thrown from the windows of the Hradčany Palace. The Bohemian rising and the victory of the Counter-Reformation
War became inevitable when Emperor Matthias died in 1619. Not that he had been master of the situation, but his death brought Ferdinand II, the most uncompromising Counter-Reformer, to the head of the house of Habsburg. Ferdinand was hard-pressed at first, as Bohemian and Moravian troops invaded Austria. A deputation of the estates of Lower Austria tried to make him renounce Bohemia in a peace treaty and demanded religious concessions for themselves, unsuccessfully. The Bohemians were forced to retreat, and imperial troops advanced into their country. The Bohemians deposed Ferdinand from the throne of Bohemia and elected Count Palatine Frederick V in his stead; two days later, however, Ferdinand II was elected Holy Roman emperor at Frankfurt (August 28, 1619).
War was the only means of resolving the issue. The conflict for the Bohemian crown developed into a European war—the so-called Thirty Years’ War—when Spain, the Bavarian duke Maximilian I, and the Protestant elector of Saxony entered the struggle on the side of the emperor. The Upper Austrian estates rashly joined Frederick V, with the result that their country was occupied by the army of the Catholic League and afterward pledged to Bavaria. At the Battle of the White Mountain, Ferdinand II became master of Bohemia, Moravia, and Silesia, while Lusatia was pledged to Saxony. King Frederick fled to the Netherlands. The leaders of the Bohemian rising were executed, and other nobles who had compromised themselves lost their property. Many Protestants left the country. In the new constitution of 1627, Bohemia and its associated lands became a hereditary kingdom. The diets were not dissolved entirely, as the government wanted to make use of their administration, but their influence was restricted to financial matters.
After the death of Matthias, Ferdinand had also inherited the Danubian territories. Tirol, however, retained a special status under a new Habsburg secundogeniture (inheritance by a second branch of the house). Upper Austria, pledged to Bavaria, was disturbed by a great peasant rising. The Protestant peasants were defeated after heavy fighting, and in 1628 the country passed into the hands of the emperor again.
The Counter-Reformation was vigorously enforced in the Austrian domains. This led to the mass emigration of Protestants, including many members of the nobility. Most went to the Protestant states and to the imperial cities of southern Germany. After the Bohemian victory the war went favourably for the emperor, and the Peace of Lübeck (1629) seemed to secure the hegemony in Germany for the Habsburgs. But in 1629 Ferdinand’s attempt in the Edict of Restitution (Restitutionsedikt) to establish religious unity by force throughout the empire provoked the violent opposition of the Protestants. Struggle with Sweden and France
July 1630 saw intervention in Germany’s religious strife from a different quarter—Sweden. In that month the Protestant Swedish king, Gustav II Adolf, landed on the Baltic coast of Pomerania. His purpose was to defend the Protestants against further oppression, to restore the dukes of Mecklenburg, his relatives, who had been driven from their lands by Ferdinand’s forces, and perhaps to strengthen Sweden’s strategic position in the Baltic. In the ensuing conflict, the German city of Magdeburg was destroyed by fire after it had been taken by the emperor’s troops under General Johann Tserclaes, Graf (count) von Tilly (1631). The North German Protestants, who had so far remained undecided, consequently went over to the Swedes. After victories in the Battle of Breitenfeld and on the Lech River, the Swedish troops entered Bavaria.
During the subsequent period of the Thirty Years’ War, Ferdinand adopted a rigorous and often unrelenting attitude, though he yielded a little when the Peace of Prague was being negotiated (1635). His successor, Ferdinand III (1637–57), was as loyal to Catholicism as his father had been but showed himself more of a realist. He was not able, however, to prevent the war from again dragging into Habsburg territory, so in 1645 even Vienna was threatened. The extremist party that had rejected all concessions lost its influence at the Vienna court, and two able diplomats, Maximilian, Graf von Trauttmansdorff, and Isaac Volmar, were entrusted with the representation of a weakened Austria at the German cities of Münster and Osnabrück, where extended negotiations were conducted until acceptable terms could be settled for Austria. In the Peace of Westphalia (1648), Austria lost its possessions in Alsace, and Lusatia had to be ceded for good to Saxony.