The city of Augsburg opened its gates to the conqueror and acknowledged his authority. Then, after attacking Ingolstadt without success, he marched upon Munich, which was unable to resist, but was spared, on condition of paying a heavy contribution. The Bavarians had buried a number of cannon under the floor of the arsenal, and news thereof came to the king's ears. "Let the dead arise!" he ordered; and 140 pieces were dug up, one of which contained 30,000 ducats. Maximilian, whose land was completely overrun by the Swedes, would gladly have made peace, but Gustavus plainly told him that he was not to be trusted. While the Protestant cause was so brilliantly victorious in the south, John George of Saxony, who had taken possession of Prague without the least trouble, remained inactive in Bohemia during the winter and spring, apparently as jealous of Gustavus as he was afraid of Ferdinand II. The Emperor had long before ceased to laugh at the "Snow King." He was in the greatest strait of his life: he knew that his trampled Austrians would rise at the approach of the Swedish army, and then the Catholic cause would be lost. Before this he had appealed to Wallenstein, who was holding a splendid court at Znaim, in Moravia; but the latter refused, knowing that he could exact better terms for his support by waiting a little longer. The danger, in fact, increased so rapidly that Ferdinand II. was finally compelled to subscribe to an agreement which practically made Wallenstein the lord and himself the subject. He gave the Duchies of Mecklenburg to Wallenstein, and promised him one of the Hapsburg States in Austria; he gave him the entire disposal of all the territory he should conquer, and agreed to pay the expenses of his army. Moreover, all appointments were left to Wallenstein, and the Emperor pledged himself that neither he nor his son should ever visit the former's camp. Having thus become absolute master of his movements, Wallenstein offered a high rate of payment and boundless chances of plunder to all who might enlist under him, and in two or three months stood at the head of an army of 40,000 men, many of whom were demoralized Protestants. He took possession of Prague, which John George vacated at his approach, and then waited quietly until Maximilian should be forced by necessity to give him also the command of the Bavarian forces. This soon came to pass, and then Wallenstein, with 60,000 men, marched against Gustavus Adolphus, who fell back upon Nuremberg, which he surrounded with a fortified camp. Instead of attacking him, Wallenstein took possession of the height of Zirndorf, in the neighborhood of the city, and strongly intrenched himself. Here the two commanders lay for nine weeks, watching each other, until Gustavus, whose force amounted to about 35,000, grew impatient of the delay, and troubled for the want of supplies. [Sidenote: 1632.]