Theological strife was the precursor of the all-devastating Thirty Years' War. The forces had been long at work before the fearful carnage began. The principles involved were of such moment that, whatever power took part in the struggle, did so with all the energy with which it was endowed. The Emperor Rudolph II. had, in 1609, guaranteed to Bohemia the liberty of Protestantism, but his successor, Matthias, violated the pledge by preventing the erection of a Protestant church edifice. The imperial councillors were cast out of the window; the priests driven off; and the Elector Frederick V. of the Palatinate, chosen King of Bohemia. But the Protestants were overcome. Ferdinand II. tore up the imperial pledge; led back the priests into authority, and expelled the Protestant clergy. Certain concessions having been previously made to the Protestants, Ferdinand II. issued in 1629 his infamous _Edict of Restitution_, by which the Protestants were to deliver up all the monasteries confiscated after the Treaty of Passau. Calvinists were excluded from the Peace; and the Catholic States were granted unconditional liberty to suppress Protestantism in their hereditary countries.[16] The fearful carnage commenced in bitter earnestness. No war was ever carried on with more desperation; none can be found more repulsive in brutality, or more beautiful in fortitude and sublime in bravery. Great sanguinary contests often receive their appellation from the influences that produce them, or the nations conducting them; but this one, extending from 1618 to 1648, combined all these elements to such an extent that the historian finds it most convenient to denominate it by the period of its duration. It was the bloody mould in which the continent of Europe received its modern shape. It extended, with but slight exceptions, over the entire extent of Germany. Some portions of that singularly picturesque country were permitted to hope for immunity from its devastations; but, by and by, they too were visited; and all that remained were a decimated population and smoking ruins.