The kings of Sweden and Denmark, appalled by the rapid strides of the imperial general, united all their strength to resist him. They threw a strong garrison into Stralsund, and sent the fleets of both kingdoms to aid in repelling the attack, and succeeded in baffling all the attempts of Wallenstein, and finally in driving him off, though he had boasted that "he would reduce Stralsund, even if it were bound to heaven with chains of adamant." Though frustrated in this attempt, the armies of Ferdinand had swept along so resistlessly, that the King of Denmark was ready to make almost any sacrifice for peace. A congress was accordingly held at Lubec in May, 1629, when peace was made; Ferdinand retaining a large portion of his conquests, and the King of Denmark engaging no longer to interfere in the affairs of the empire. Ferdinand was now triumphant over all his foes. The Protestants throughout the empire were crushed, and all their allies vanquished. He now deemed himself omnipotent, and with wild ambition contemplated the utter extirpation of Protestantism, and the subjugation of nearly all of Europe to his sway. He formed the most intimate alliance with the branch of his house ruling over Spain, hoping that thus the house of Austria might be the arbiter of the fate of Europe. The condition of Europe at that time was peculiarly favorable for the designs of the emperor. Charles I. of England was struggling against that Parliament which soon deprived him both of his crown and his head. France was agitated, from the Rhine to the Pyrenees, by civil war, the Catholics striving to exterminate the Protestants. Insurrections in Turkey absorbed all the energies of the Ottoman court, leaving them no time to think of interfering with the affairs of Europe. The King of Denmark was humiliated and prostrate. Sweden was too far distant and too feeble to excite alarm. Sigismond of Poland was in intimate alliance with the emperor. Gabriel Bethlehem of Hungary was languishing on a bed of disease and pain, and only asked permission to die in peace. The first step which the emperor now took was to revoke all the concessions which had been granted to the Protestants. In Upper Austria, where he felt especially strong, he abolished the Protestant worship utterly. In Lower Austria he was slightly embarrassed by engagements which he had so solemnly made, and dared not trample upon them without some little show of moderation. First he prohibited the circulation of all Protestant books; he then annulled all baptisms and marriages performed by Protestants; then all Protestants were excluded from holding any civil or military office; then he issued a decree that all the children, without exception, should be educated by Catholic priests, and that every individual should attend Catholic worship. Thus coil by coil he wound around his subjects the chain of unrelenting intolerance.