Maximilian, Duke of Bavaria, and Frederick, Elector Palatine, were at that time the chiefs of the rival confederacies. Though the Bohemians had chosen the leader of the Union as their king, the Protestant princes, and still more the Protestant free towns, from the first showed little sympathy for the Bohemian cause. The records of this period are mostly written from the point of view of religious controversy, and generally leave other motives in the background. It, however, appears probable that the hereditary hatred between Slavs and Germans contributed to preventing the German Protestants from co-operating with those of Bohemia. The princes of the Union strongly protested against Frederick's action in leading some of the troops of the Union to Bohemia. They even wished to deprive him of his position as head of their confederacy, alleging that he had by his acceptation of the Bohemian throne rendered himself unable to perform the duties attached to that office.
The ability of Duke Maximilian of Bavaria, assisted by the efforts of the French envoys, was thus enabled to achieve a diplomatic success, which may be said to have sealed the fate of Frederick. The new Emperor had after his coronation visited Duke Maximilian at Munich (October 1619). It seems probable that at this moment already the Emperor promised Maximilian, in return for his assistance against Bohemia, that the dignity of Elector should, after the defeat of Frederick, be transferred from the Protestant to the Catholic line of the house of Wittelsbach. It was now only necessary for Duke Maximilian to acquire the certainty that his own dominions would not be attacked; he would then be able to use against Bohemia the whole strength of the Catholic "Liga." This result was only obtained after protracted negotiations, during which Maximilian received great assistance from the French ambassadors, who were instructed directly to menace the German Protestants. A treaty was at last signed at Ulm (July 3, 1620), by Duke Maximilian on behalf of the Catholic, and by the Elector of Brandenburg on behalf of the Protestant princes and free towns of Germany. By this agreement both parties pledged themselves not to attack the German lands belonging to the other party. Bohemia was not included in this treaty, and thus remained exposed to the attack of the "Liga." The very fair demand of the Protestants that the Archduke Albert, governor of the Spanish Netherlands, should undertake not
