But beyond the Danube had arisen a new power, the independence of which, after the time of Aurelian, was never disputed by the Roman Emperors. The Goths were the first of the Germanic tribes to adopt a monarchical form of government, and to acquire some degree of civilization. They were numerous and well organized; and Constantine, who was more of a diplomatist than a general, found it better to preserve peace with them for forty years, by presents and payments, than to provoke them to war. His best soldiers were enlisted among them, and it was principally the valor of his Gothic troops which enabled him to defeat the rival emperor, Licinius, in 325. From that time, 40,000 Goths formed the main strength of his army. [Sidenote: 350.] The important part which these people played in the history of Europe renders it necessary that we should now sketch their rise and growth as a nation. First, however, let us turn to Western and Northern Germany, where the development of the new nationalities was longer delayed, and describe the last of their struggles with the power of Rome, during the fourth century. After the death of Constantine, in 337, the quarrels of his sons and brothers for the Imperial throne gave the Germans a new opportunity to repeat their invasions of Gaul. The Franks were the first to take advantage of it: they got possession of Belgium, which was not afterwards retaken. The Alemanni followed, and planted themselves on the western bank of the Rhine, which they held, although Strasburg and other fortified cities still belonged to the Romans. About the year 350, a Frank or Saxon, of the name of Magnentius, was proclaimed Emperor by a part of the Roman army. He was defeated by the true Emperor, Constantius II., but the victory seems to have exhausted the military resources of the latter, for immediately afterwards another German invasion occurred. This time, the Franks took and pillaged Cologne, the Alemanni destroyed Strasburg and Mayence, and the Saxons, who had now become a sea-faring people, visited the northwestern coasts of Gaul. Constantius II. gave the command to his nephew, Julian (afterwards, as Emperor, called the Apostate), who first retook Cologne from the Franks, and then turned his forces against the Alemanni. The king of the latter, Chnodomar, had collected a large army, with which he encountered Julian on the banks of the Rhine, near Strasburg. The battle which ensued was fiercely contested; but Julian was completely victorious. Chnodomar was taken prisoner, and only a few of his troops escaped, like those of Ariovistus, 400 years before, by swimming across the Rhine. Although the season was far advanced, Julian followed them, crossed their territory to the Main, rebuilt the destroyed Roman fortresses, and finally accepted an armistice of ten months which they offered to him.