Next to Hungary and Bohemia, Saxony was perhaps the most powerful State of the Germanic confederacy. The emperor placed full reliance upon Maurice, and the Protestants in their despair would have thought of him as the very last to come to their aid; for he had marched vigorously in the armies of the emperor to crush the Protestants, and was occupying the territories of their most able and steadfast friend. Secretly, Maurice made proposals to all the leading Protestant princes of the empire, and having made every thing ready for an outbreak, he entered into a treaty with the King of France, who promised large subsidies and an efficient military force.
Maurice conducted these intrigues with such consummate skill that the emperor had not the slightest suspicion of the storm which was gathering. Every thing being matured, early in April, 1552, Maurice suddenly appeared before the gates of Augsburg with an army of twenty-five thousand men. At the same time he issued a declaration that he had taken up arms to prevent the destruction of the Protestant religion, to defend the liberties of Germany which the emperor had infringed, and to rescue his relatives from their long and unjust imprisonment. The King of France and other princes issued similar declarations. The smothered disaffection with the emperor instantly blazed forth all over the German empire. The cause of Maurice was extremely popular. The Protestants in a mass, and many others, flocked to his standard. As by magic and in a day, all was changed. The imperial towns Augsburg, Nuremberg and others, threw open their gates joyfully to Maurice. Whole provinces rushed to his standard. He was everywhere received as the guardian of civil and religious liberty. The ejected Protestant rulers and magistrates were reinstated, the Protestant churches opened, the Protestant preachers restored. In one month the Protestant party was predominant in the German empire, and the Catholic party either neutral or secretly favoring one who was humbling that haughty emperor whom even the Catholics had begun to fear. The prelates who were assembling at Trent, alarmed by so sudden and astounding a revolution, dissolved the assembly and hastened to their homes.