The memorable contest between the two great generals--Gustavus Adolphus and Wallenstein--was brought to a tragic close in the late autumn of the same year on the fateful field of Lützen. Wallenstein was defeated, but Gustavus was killed. Although the Swedes continued the struggle, they were comparatively few in numbers and possessed no such general as their fallen king. On the other side, Wallenstein's loyalty could not be depended upon; rumors reached the ear of the emperor that his foremost general was negotiating with the Protestants to make peace on his own terms; and Wallenstein was assassinated in his camp by fanatical imperialists (February, 1634). The tragic removal of both Wallenstein and Gustavus Adolphus, the economic exhaustion of the whole empire, and the national desire on the part of many Protestant princes, as well as on the part of the Catholic emperor, to rid the Germanies of foreign soldiers and foreign influence--all these developments seemed to point to the possibility of concluding the third, or Swedish, period of the war, not perhaps as advantageously for the imperialist cause as had ended the Bohemian revolt or the Danish intervention, but at any rate in a spirit of reasonable compromise. In fact, in May, 1635, a treaty was signed at Prague between the emperor and such princes as were then willing to lay down their arms, whereby all the military forces in the empire were henceforth to be under the direct control of the emperor (with the exception of a contingent under the special command of the Lutheran elector of Saxony); all princely leagues within the empire were to be dissolved; mutual restoration of captured territory was to be made; and, as to the fundamental question of the ownership of ecclesiastical lands, it was settled that any such lands actually held in the year 1627, whether acquired before or after the religious peace of Augsburg of 1555, should continue so to be held for forty years or until in each case an amicable arrangement could be reached. What wrecked the peace of Prague was not so much the disinclination of the Protestant princes of Germany to accept its terms as the policy of Cardinal Richelieu of France. Richelieu was convinced more than ever that French greatness depended upon Habsburg defeat; he would not suffer the princes to make peace with the emperor until the latter was soundly trounced and all Germany devastated; instead of supplying the Swedes and the German Protestants with assistance from behind the scenes, he now would come boldly upon the stage and engage the emperor in open combat. [Sidenote: 4. French Intervention. Richelieu's Policy in the Germanies]