Another important development of this period was an eventful one for Europe. There was a large class of young men, younger sons of nobles, for whom there was no suitable classification. They were proud and by necessity were idle. This same Saxon King Henry invited these young men to serve the empire in a new and peculiar way. They must be men of honor and truth; they must be devoted and loyal to the Holy Roman Empire; never have injured a weak woman nor run away in battle; they must be gentle and courteous and brave, and faithful to the Church. The men who could take these oaths and make these pledges were called knights, or _Knechts_, servants of the King. Thus was created the order of knighthood, which quickly spread over Europe. The great Charlemagne, in accepting the crown of the Holy Roman Empire in 800, unconsciously inflicted a deep injury upon the future Germany. That glittering bauble, the crown of the Cæsars, was very costly, and retarded the development of Germany for centuries. That country needed all her resources and energies at home, to solidify and develop a great nation during its formative period. Instead of that, for seven hundred years the ambitions of the Kings of Germany were diverted from what should have been their first care--the unity and prosperity of their own nation; and were chasing a phantom--the re-establishment of the great old empire, with Rome as its heart and center. Another mistake made by Charlemagne was far-reaching in its consequences. He little suspected the nature and the latent power existing in that spiritual kingdom with which he formed so close an alliance. He feared not the Church, but the ambitious and scheming nobles. So, in order to create a friendly bulwark about the throne, he made some of the archbishops and bishops secular princes, and bestowed upon them dominions over which they might reign as sovereigns. The Church, which had not been growing any too spiritual since it was adopted by Rome, was more and more secularized when it had Primates ravenous for wealth and power. The Pope and Emperor, instead of close allies as Charlemagne had intended, had finally become jealous and angry rivals. In the open warfare which in time developed two political parties came into being--the Guelphs and the Ghibellines, which represented the adherents of the Pope and the Emperor. It was a part of the settled policy of the Popes to stir up strife in Italy, and thus, by compelling the Emperor to pour his revenues and his energies into that land, to weaken and undermine him at home.