For his part, the Emperor agreed not to attack him in case there was a common war against all Protestants. These arrangements for special terms led to the collapse of Philip's position as leader of the Protestant party. He had become an object of suspicion, and, although the league continued to remain in force, and gained some new adherents in succeeding years, its real power had dissipated. But while only Albrecht VII, Duke of Mecklenburg, and Henry V, Duke of Brunswick-Lüneburg, of the secular princes were still faithful to the Roman Catholic cause, and while united action might at the time easily have resulted in the triumph of Protestantism, there was no union of purpose. Duke Maurice of Saxony and Joachim II of Brandenburg would not join the Schmalkaldic League; Cleves was successfully invaded by imperial troops; and Protestantism was rigorously suppressed in Metz.