‘It is the cardinal principle of the law of the Roman Empire,’ wrote Otto of Freising, ‘that the succession depends not upon hereditary right, but on the election of the princes.’ According to this precept the magnates of Germany met in March 1152 at Frankfurt to appoint a successor to Conrad III. Some of the barons of Italy attended the assembly. ‘There were,’ wrote Otto, ‘two mighty houses in the Roman Empire, one that of the Henrys of Weiblingen, the other that of the Welfs of Altorf. The one was wont to furnish mighty emperors, the other puissant dukes. These families, jealous of each other, had been long accustomed to disturb the tranquillity of the commonwealth by their feuds, but in the days of Henry V. Frederick, the duke, representative of the royal stock, had married the daughter of Henry, Duke of the Bavarians, the representative of the ducal family. The offspring of this union was Duke Frederick, and the princes, regarding not only the energy and valour of the young duke, but considering that he shared the blood of both houses, and like a corner-stone could bind the two together, chose him as their king that thus with God’s blessing he might end their ancient quarrel.’ [Sidenote: Frederick’s policy.] The new king was well worthy of the general confidence which he inspired. Already thirty years of age, he had abundantly displayed rare gifts both as a statesman and as a general. He had administered his duchy of Swabia with energy and success. He had combined loyalty to his uncle Conrad with friendship for his cousin Henry the Lion, and his mediation had saved Duke Welf VI. in the time of his greatest disaster. His exploits on the Crusade had spread abroad his fame, and the few survivors who had reached home in safety recognised that they owed their lives to his courage and policy. He was admired for his kingly bearing and fair proportions, for the chivalry and generosity of his character, for his independent attitude towards the Church, for the subtle policy so rarely combined with the simple virtues of the hero of romance.