Frederick V entered Prague and was crowned king by the rebel Estates in October 1619, but already the Catholic net was closing around him. The axis linking Vienna with Munich, Brussels, and Madrid enjoyed widespread support: subsidies came from Rome and Genoa, while Tuscany and Poland sent troops. Equally serious, states favourable to Frederick’s cause were persuaded to remain neutral: Spanish diplomacy kept England out of the war, while French efforts persuaded the Protestant Union to remain aloof from the Bohemian adventure of their leader. The Dutch Republic also did nothing, so that in the summer of 1620 a Spanish army was able to cross from the Netherlands and occupy the Rhine Palatinate. Meanwhile, the armies of the emperor and League, reinforced with Spanish and Italian contingents, invaded the rebel heartland. On November 8, in the first significant battle of the war, at the White Mountain outside Prague, Frederick’s forces were routed. The unfortunate prince fled northward, abandoning his subjects to the mercy of the victorious Ferdinand.

This was total victory, and it might have remained the last word but for events in the Low Countries. Once the Twelve Years’ Truce expired in April 1621, the Dutch, fearing a concerted attack by both Spanish and Austrian Habsburgs, decided to provide an asylum for the defeated Frederick and to supply diplomatic and, eventually, military assistance to his cause. In 1622 and again in 1623, armies were raised for Frederick with Dutch money, but they were defeated. Worse, the shattered armies retreated toward the Netherlands, drawing the Catholic forces behind them. It began to seem that a joint Habsburg invasion of the republic was inevitable after all.

The emperor’s political position, however, weakened considerably in the course of 1623. Although his armies won impressive victories in the field, they were only able to do so thanks to massive financial and military support from the Catholic League, controlled by Maximilian of Bavaria. Ferdinand II, thanks to the Spanish and papal subsidies, maintained some 15,000 men himself, but the League provided him with perhaps 50,000. Thus, Maximilian’s armies had, in effect, won Ferdinand’s victories and, now that all common enemies had been defeated, Maximilian requested his reward: the lands and electoral title of the outlawed Frederick of the Palatinate. Don Balthasar de Zúñiga, chief minister of Ferdinand’s other major ally, Spain, warned that the consequences of acceding to this demand could be serious, but in October 1622 he died, and no one else in Madrid—least of all his successor as principal minister, the Count-Duke of Olivares—had practical experience of German affairs; so in January 1623 the emperor felt able to proceed with the investiture of Maximilian as elector Palatine.

Zúñiga, however, had been right: the electoral transfer provoked an enormous outcry, for it was clearly unconstitutional. The Golden Bull of 1356, which was universally regarded in Germany as the fundamental and immutable law of the empire, ordained that the electorate should remain in the Palatine house in perpetuity. The transfer of 1623 thus undermined a cornerstone of the Constitution, which many regarded as their only true safeguard against absolute rule. Inside Germany, a pamphlet war against Maximilian and Ferdinand began; outside, sympathy for Frederick at last created that international body of support for his cause which had previously been so conspicuously lacking. The Dutch and the Palatine exiles found little difficulty in engineering an alliance involving France, England, Savoy, Sweden, and Denmark that was dedicated to the restoration of Frederick to his forfeited lands and titles (the Hague Alliance, December 9, 1624). Its leader was Christian IV of Denmark (1588–1648), one of the richest rulers in Christendom, who saw a chance to extend his influence in northern Germany under cover of defending “the Protestant cause.” He invaded the empire in June 1625.

The Protestants’ diplomatic campaign had not gone unnoticed, however. Maximilian’s field commander, Count Tilly, warned that his forces alone would be no match for a coalition army and asked that the emperor send reinforcements. Ferdinand obliged: in the spring of 1625 he authorized Albrecht von Wallenstein, military governor of Prague, to raise an imperial army of 25,000 men and to move it northward to meet the Danish threat. Wallenstein’s approach forced Christian to withdraw; when the Danes invaded again the following year, they were routed at the Battle of Lutter (August 26, 1626). The joint armies of Tilly and Wallenstein pursued the defeated forces: first they occupied the lands of North German rulers who had declared support for the invasion, then they conquered the Danish mainland itself. Christian made peace in 1629, promising never again to intervene in the empire. His allies had long since withdrawn from the struggle.

The White Mountain delivered the Bohemian rebels into the emperor’s grasp; Lutter delivered the rebels’ German supporters. After the victories, important new policies were initiated by Ferdinand which aimed at exalting the Catholic religion and his own authority. In the Habsburg provinces there was widespread confiscation of land—perhaps two-thirds of the kingdom of Bohemia changed hands during the 1620s—and a new class of loyal landowners—like Wallenstein—was established. At the same time, the power of the Estates was curtailed and freedom of worship for Protestants was restricted (in some territories) or abolished (in most of the rest). Even a rebellion in Upper Austria in 1626, provoked principally by the persecution of Protestants, failed to change Ferdinand’s mind. Indeed, fortified by his success in the Habsburg lands, he decided to implement new policies in the empire. First, disloyal rulers were replaced (the Palatinate went to Maximilian, Mecklenburg to Wallenstein, and so on). Next, serious steps were taken to reclaim church lands that had fallen into Protestant hands. At first this was done on a piecemeal basis, but on March 28, 1629, an Edict of Restitution was issued which declared unilaterally that all church lands secularized since 1552 must be returned at once, that Calvinism was an illegal creed in the empire, and that ecclesiastical princes had the same right as secular ones to insist that their subjects should be of the same religion as their ruler. The last clause, at least, was clearly contrary to the terms of the Peace of Augsburg, which Protestants regarded as a central pillar of the Constitution. There was, however, no opportunity for argument, for the imperial edict was enforced immediately, brutally, by the armies of Wallenstein and Tilly, which now numbered some 200,000 men. The people of the empire seemed threatened with an arbitrary rule against which they had no defense. It was this fear, skillfully exploited once again by Protestant propagandists, which ensured that the war in Germany did not end in 1629 with the defeat of Denmark. Ferdinand may have won numerous military victories, but in doing so he had suffered a serious political defeat. The pens of his enemies proved mightier than the sword.