THIRTY YEARS' WAR (1618-1648), the general name of a series of wars in Germany which began formally with the claim of Frederick, the elector palatine, to the throne of Bohemia and ended with the treaty of Westphalia. It was primarily a religious war and was waged with the bitterness characteristic of such wars, but at the same time political quarrels were interwoven with the religious question : with the consequence that the armies, considering themselves as their masters' retainers rather than champions of a cause, plundered and burned everywhere, military violence being in no way restrained by expediency.
Formation of the "Union" and the "League."—Fifty years before the outbreak of the war the Convention of Passau had compromised the burning questions of the Reformation, but had left other equally important points as to the secularization of church lands and the consecration of Protestant bishops to the future. Each such case, then, came before the normal government machine—a Diet so constituted that even though at least half of the secular princes and nine-tenths of their subjects were Pro testants, the voting majority was Catholic. Moreover, the Jesuits had rallied and disciplined the forces of Catholicism, while Prot estantism, however firm its hold on the peoples, had dissipated itself in doctrinal wrangles. The strongest side was that which represented conservatism, peace and Catholicism. Realizing this from the preliminary mutterings of the storm, the Protestant princes formed a "Union," which was promptly answered by the Catholic League. This group was headed by the wise and able Maximilian of Bavaria and supported by his army, which he placed under a soldier of long experience and conspicuous ability, Count Tilly.
The Bohemian Movement.—The war arose in Bohemia, where the Protestant magnates refused to elect Ferdinand of Austria to the vacant throne, offering it instead to Frederick, the elector palatine. But the aggrandizement of this elector's power was entirely unacceptable to most of the Protestant princes—to John George of Saxony above all. They declared themselves neu tral, and Frederick found himself an isolated rebel against the Emperor Ferdinand.
Even thus early the struggle showed itself in the double aspect of a religious and a political war. Just as the Bohemians and their nominee found themselves looked upon askance by the other Protestants, so the emperor himself was unable to call upon Max imilian's Army of the League without promising to aggrandize Bavaria. Only the incoherence of the rebels saved Ferdinand. They ordered taxes and levies of soldiers, but the taxes were not collected, and the soldiers, unpaid and unfed, plundered the country-side. The only coherent force was the mercenary corps of Ernst von Mansfeld, which, thrown out of employment by the termination of a war in Italy, had entered the service of Frederick. Nevertheless, the Bohemians were conspicuously successful at the outset : they won several engagements, and appeared before Vienna itself. Moravia and Silesia supported the Bohemians, anc: the Austrian nobles attempted, in a stormy conference, to wrest from Ferdinand not only religious liberty but also political rights that would have made Austria and Bohemia a loose confederation of powerful nobles. Ferdinand firmly refused, though the deputa tion threatened him to his face, and the tide ebbed as rapidly as it had flowed. No sooner had Frederick accepted the crown than Maximilian let loose the Army of the League. Spanish aid ar rived. Spinola with 20,000 men from the Low Countries and Franche Comte invaded the Palatinate, and Tilly, with a combined army of Austrians and Bavarians crushed the Bohemians at the battle of the Weisser Berg near Prague (Nov. 8-18, 162o). With this the Bohemian war ended. Some of the nobles were executed, and Frederick, the "Winter King," was put to the ban of the empire. But the emperor's revenge alarmed the Union princes. They were Protestants, and neither in religion nor in politics could they suffer an all-powerful Catholic emperor. Moreover, the al ternative to a powerful emperor was a powerful Bavaria, and this they liked almost as little.