In June 1546, only four months after Martin Luther died in Eisleben, a disaster befell the Lutherans in Germany. While hiding his true intentions, Emperor Charles V launched a military campaign against the German Protestant princes to solve by force the problem of Christendom's split. Duke Moritz of Albertine Saxony, a cousin of Elector Johann Friedrich of Saxony, took the emperor's side despite his Protestant faith, and his invasion of Ernestine Saxony aggravated the situation in the Lutheran camp. On 24 April 1547, surprised by the imperial army at Mühlberg, Johann Friedrich's force was completely crushed and the Elector himself became a prisoner. The defeat at Mühlberg was an apparent fatal blow for the Protestant cause. As the Landgrave Philip of Hesse surrendered and became a prisoner, the resistance of the Schmalkaldic League immediately collapsed, and Wittenberg also capitulated to the imperial army in May 1547. Next spring, the victorious emperor tried to impose his provisional religious settlement, commonly called the Augsburg Interim, on Protestant territories in order to restore Catholic practices. Soon the Lutheran camp split into two groups over the question of whether they should keep fighting against the emperor' religious policy or make concessions on some theological points and come to peace with him. Those who chose to compromise formulated a new religious settlement nicknamed the ‘Leipzig Interim’ to appease the emperor, but the opposing group strenuously rejected it as a hideous compromise with the Antichrist.