Armed with such enormous power, Wallenstein consented to place himself at the head of the army. He marched to Prague, and without difficulty took the city. Gradually he drove the Saxon troops from all their fortresses in Bohemia. Then advancing to Bavaria, he effected a junction with Bavarian troops, and found himself sufficiently strong to attempt to arrest the march of Gustavus. The imperial force now amounted to sixty thousand men. Wallenstein was so sanguine of success, that he boasted that in a few days he would decide the question, whether Gustavus Adolphus or Wallenstein was to be master of the world. The Swedish king was at Nuremberg with but twenty thousand men, when he heard of the approach of the imperial army, three times outnumbering his own. Disdaining to retreat, he threw up redoubts, and prepared for a desperate defense. As Wallenstein brought up his heavy battalions, he was so much overawed by the military genius which Gustavus had displayed in his strong intrenchments, and by the bold front which the Swedes presented, that notwithstanding his boast, he did not dare to hazard an attack. He accordingly threw up intrenchments opposite the works of the Swedes, and there the two armies remained, looking each other in the face for eight weeks, neither daring to withdraw from behind their intrenchments, and each hoping to starve the other party out. Gustavus did every thing in his power to provoke Wallenstein to the attack, but the wary general, notwithstanding the importunities of his officers, and the clamors of his soldiers, refused to risk an engagement. Both parties were all the time strengthening their intrenchments and gathering reinforcements. At last Gustavus resolved upon an attack. He led his troops against the intrenchments of Wallenstein, which resembled a fortress rather than a camp. The Swedes clambered over the intrenchments, and assailed the imperialists with as much valor and energy as mortals ever exhibited. They were, however, with equal fury repelled, and after a long conflict were compelled to retire again behind their fortifications with the loss of three thousand of their best troops. For another fortnight the two armies remained watching each other, and then Gustavus, leaving a strong garrison in Nuremberg, slowly and defiantly retired. Wallenstein stood so much in fear of the tactics of Gustavus that he did not even venture to molest his retreat. During this singular struggle of patient endurance, both armies suffered fearfully from sickness and famine. In the city of Nuremberg ten thousand perished. Gustavus buried twenty thousand of his men beneath his intrenchments. And in the imperial army, after the retreat of Gustavus, but thirty thousand troops were left to answer the roll-call.