In the sixteenth century the Reformation, spreading throughout the North of Europe, undermined the basis of the Teutonic Order. The Grand Master of the time transformed himself into a Lutheran Prince holding the hereditary Duchy of Prussia as a vassal of the King of the neighbouring Slavonic State of Poland. In 1611 the Duchy was amalgamated with the territory of Brandenburg farther west, and in 1647 the enlarged Prussian territories won their emancipation from Poland. Prussia now became a distinct State, essentially German in character (as opposed to the Poles and Lithuanians on its Eastern border), but still remaining for a time outside the community of the other German States.
The union between Prussia and Brandenburg had brought Prussia under the rule of the House of Hohenzollern, which, although originally a South German family, had borne rule in Brandenburg since 1415. Under the Hohenzollerns Prussia rapidly increased in territory and influence until in 1701 the ruler of the day, the grandfather of Frederick the Great, took on himself the title of King. Under Frederick the Great, Prussia's career of conquest and aggrandisement continued. Seizing a convenient opportunity, he invaded and annexed the Austrian province of Silesia, and later joined with Austria and Russia in promoting the shameful Partition of Poland. The old conquering and "civilising" policy of the Teutonic Knights was continued, but under new conditions and in a brutal and cynical spirit which rendered it impossible of success. "The surest means of giving this oppressed nation better ideas and morals," wrote Frederick the Great, in words quoted with approval by Prince Bülow, "will always be gradually to get them to intermarry with Germans, even if at first it is only two or three of them in every village." This spirit in Prussian policy may have extinguished the ancient Prussians, but it has not yet begun to Germanise the Poles, and has gone far to de-Germanise the Alsatians. But it explains the utterances and justifies the sincerity of those who believe that to-day, as in the early days of her history, Prussia is fighting on behalf of "culture."
Prussia remains to-day, what she has been for the last two centuries, an aggressive military monarchy. "Prussia attained her greatness," says Prince Bülow, "as a country of soldiers and officials, and as such she was able to accomplish the work of German union; to this day she is still, in all essentials, a State of soldiers and officials." Power rests in the hands of the monarch and of a bureaucracy of military and civil officials, responsible to him alone, and traditionally and fanatically loyal to the monarch who is, before all things, their War Lord.