The formation of the Schmalkaldic League, in 1542, had already prepared the Protestants for collective action; and the threatening attitude of Charles V., coupled with the proposal for a Council, which would undoubtedly condemn Protestantism, seemed to many of the more eager spirits to justify immediate action. The Landgrave of Hesse and John Frederick, Elector of Saxony, determined to anticipate the attacks of Charles; and, not many months after Luther’s death, they marched into Bavaria and attacked the town of Ingolstadt. But, scarcely was this step taken, when it was discovered that Charles had provided against the attacks of his enemies, by bringing to his side one of the most formidable of them. Moritz of Saxony had been induced, by the promise of his cousin’s lands, to desert the cause of the Protestants, and to secure his new possession by force of arms. Ferdinand hoped to reconcile the Bohemians to Moritz by persuading him to renew a former treaty of hereditary alliance between Saxony and Bohemia.
But the Protestant feeling of Bohemia was too strong to be juggled with in this manner; and, on March 18, 1546, a League had already been formed for the protection of the civil and religious liberties of Bohemia. They even went so far as to appoint a Committee of Eight, who were to manage the affairs of the kingdom, and to raise arms and men without asking the leave of the king. When, then, John Frederick of Saxony suddenly entered Silesia, and seized on the monastery of Dobrilug, Ferdinand found that large numbers of the Bohemians refused to repel this invasion of Bohemian territory; and even those who went to the war were unwilling to fight. Though Ferdinand at once sentenced to death the leading mutineers, he could not hinder the citizens of Prague from further negotiations with John Frederick. From refusal to fight they rapidly passed into more active opposition; and at last they even enabled Caspar Pflug to raise forces for the assistance of the Elector.
As the struggle went on, the enthusiasm of the Bohemians rose; and on April 7, 1547, the fiercer spirits of Prague suddenly seized the Town Council Houses and bridges into their own hands, demanded a safe-conduct for one of the men whom Ferdinand had just condemned for mutiny, and insisted on the imprisonment of one of Ferdinand’s Councillors, and the recall to the Teyn Church of a preacher who had been expelled for heresy. They even compelled many of the Catholic leaders to give in their adherence to the League; and all seemed ready for an actual revolution. Suddenly, while the excitement was still at its height, the news came that John Frederick of Saxony had been completely overthrown at the battle of Mühlberg. Instantly the more timid of the conspirators deserted the League, and even sent congratulations to Ferdinand on his victory. But the fiercer spirits desired to fight it out; and, as the troops of Ferdinand and Charles advanced upon Prague, the citizens rang the alarm bell, and the peasants flocked in with their flails from the neighbouring villages, and repelled the first advance of the royal forces. The Burgomasters and leading Councillors had had no desire to resist the King; but they were completely overborne by the fiercer citizens; and, on the 6th of July, the anniversary of the death of Jan Hus, an appeal was sent round to the nearest Circles, calling on all the citizens to come to the defence of Prague. Yet, in spite of this apparent vigour, there was little real vitality in the movement; the leaders of the League had hoped for the help of the Saxons; and when that failed, they had had no desire to continue the struggle. The men who had now undertaken the defence were utterly unorganised, and without any capable leaders. The first forces, who came in from the neighbouring districts were defeated by the troops of Charles; and, on the 8th of July, the city consented to submit unconditionally to Ferdinand.