Lutheranism, which absorbed nearly all northern Germany between the Main and the Baltic, drew its strength especially from the support of the north German princes. Luther himself effected a closer alliance with the princes and the nobles than he did with the people. It was to them he appealed for protection in the days of his earlier struggles, on them that he trustfully leaned in the later days of his power. Naturally, therefore, Lutheranism gave a strong impulse and sanction to the desire, which the northern princes uniformly felt, to assert their independence of a Catholic emperor. Calvinism, spreading from republican Switzerland down the upper valley of the Rhine into the heart of Germany, had a no less fatal influence upon the centralising policy of the Emperors. Subversive in its tendencies and impatient of recognised authority, it intensified the spirit of dislike to autocratic institutions. [Sidenote: =Effect of the rivalry with France.=] Still, in spite of the terrible disruption of Germany caused by the Reformation, a sovereign so powerful and so cautious as Charles V. might have been able to weather the storm, without suffering any loss of prerogative or influence, had it not been for the constant and paramount necessity laid upon him of counteracting the machinations of an enemy ever wakeful and absolutely unscrupulous. As long as Francis I. lived Charles V. was never able seriously to apply himself to German affairs. When he was dead it was too late. The religious divisions of Germany had taken definite political shape, and were inspired with definite political ambitions. The Emperor had ceased to be the acknowledged political head of Germany. He had sunk into the inferior position of becoming merely the chief of one political and religious party. [Sidenote: =Consequent disunion of Germany.=]