It was now the turn of Ferdinand to tremble. The only person who could save him was dismissed and disgraced. Tilly was dead. Munich and Prague were in the hands of the Protestants, while the king of Sweden traversed Germany as a conqueror, law giver, and judge. No fortress was inaccessible; no river checked his victorious career. The Swedish standards were planted in Bavaria, Bohemia, the Palatinate, Saxony, and along the banks of the Rhine. Meanwhile the Turks were preparing to attack Hungary, and a dangerous insurrection threatened his own capital. None came to his assistance in the hour of peril. On all sides, he was surrounded by hostile armies, while his own forces were dispirited and treacherous. [Sidenote: Wallenstein Reinstated in Power.] From such a hopeless state he was rescued by the man whom he had injured, but not until he had himself to beg his assistance. Wallenstein was in retirement, and secretly rejoiced in the victories of the Swedish king, knowing full well that the emperor would soon be compelled to summon him again to command his armies. Now he could dictate his terms. Now he could humiliate his sovereign, and at the same time obtain all the power his ambition craved. He declined entering his service unless he had the unlimited command of all the armies of Austria and Spain. No commission in the army was to be granted by the emperor, without his own approval. He demanded the ordinary pay, and an imperial hereditary estate. In short, he demanded sovereign authority; and with such humiliating terms the emperor, in his necessities, was obliged to comply. [Sidenote: Death of Gustavus Adolphus.]