Now, much at the same time that the civil wars were being fought in England--that is, not quite three hundred years ago--the Reformation had produced in Germany also very violent quarrels. Vienna, which was the seat of the Imperial House, stood for the Catholic or traditional cause, and most Germans adhered to that cause. But certain of the Northern German principalities and counties took up the side of the Reformation. A terrible war, known as the Thirty Years' War, was fought between the two factions. It enormously reduced the total population of Germany. In the absence of exact figures we only have wild guesses, such as a loss of half or three-quarters. At any rate, both from losses from the adherence of many princes to the Protestant cause and from the support lent to that cause for political reasons by Catholic France, this great civil war in Germany left the Protestant part more nearly equal in numbers to the Catholic part, and, among other things, it began to make the Elector of Brandenburg with his Prussians particularly prominent as the champion of the Protestant cause. For, of all the warring towns, counties, principalities, and the rest, Prussia had in particular shown military aptitude. From that day to this the advance of Prussia as, first, the champion, then the leader, and at last the master of Northern Germany as a whole (including many Catholic parts in the centre and the south), has been consistent and almost uninterrupted. The "Great Elector" (as he was called) formed an admirable army some two hundred years ago. His grandson Frederick formed a still better one, and by his great capacities as a general, as well as by the excellence of his troops, gave Prussia a military reputation in the middle of the eighteenth century which has occasionally been eclipsed, but has never been extinguished. Frederick the Great did more than this. He codified and gave expression, as it were, to the Prussian spirit, and the manifestation of that spirit in international affairs is generally called the "Frederician Tradition." This "Frederician Tradition" must be closely noted by the reader, because it is the principal moral cause of the present war. It may be briefly and honestly put in the following terms:-- "The King of Prussia shall do all that may seem to advantage the kingdom of Prussia among the nations, notwithstanding any European conventions or any traditions of Christendom, or even any of those wider and more general conventions which govern the international conduct of other Christian peoples." For instance, if a convention of international morals has arisen--as it did arise very strongly, and was kept until recent times--that hostilities should not begin without a formal declaration of war, the "Frederician Tradition" would go counter to this, and would say: "If ultimately it would be to the advantage of Prussia to attack without declaration of war, then this convention may be neglected."