In the early spring of 1529, the Emperor called the famous Second Diet of Spires. The states of the empire assembled with great readiness. "The papal party especially mustered all their forces and assumed a warlike and insulting attitude. Never on any like occasion had there appeared so large an assemblage of spiritual nobles; and these more than any betrayed by their looks and manners the malignity of their designs. One or two princes, who had hitherto been considered neutral or even favorable to the Reformation, now declared against it. Others came, attended by considerable escorts of cavalry, breathing hatred and defiance. Nothing less was meditated than the immediate extinction of the heresy by the sword."
The imperial message assumed a high and despotic tone. The Emperor complained of the changes in religion, and the disrespect which had been shown to his own authority: for he claimed to be the chief of the christian world, and demanded unreserved obedience to his decrees. He observed that the religious innovations which he had proscribed were daily increasing in numbers, and that too under the pretext of the edict of Spires in 1526, which edict, by virtue of his absolute power, he abrogated as in direct opposition to his orders.
The decree of the Emperor was highly offensive and grievous to the German nobles. It struck at the very root of their privileges and their independence. The evangelical princes and the deputies of the free cities took up a strong but a just position. They affirmed that the edict of Spires had been drawn up according to the usual forms; that the commissioners to the Emperor had consented to it in his name; that it was the legal act of the whole body of the Republic; and that it was beyond the imperial power to annul it.