While Cæsar was in Britain, in the year 53 B. C., the newly subjugated Celtic and German tribes which inhabited Belgium rose in open revolt against the Roman rule. The rapidity of Cæsar's return arrested their temporary success, but some of the German tribes to the eastward of the Rhine had already promised to aid them. In order to secure his conquests, the Roman general determined to cross the Rhine again, and intimidate, if not subdue, his dangerous neighbors. He built a second bridge, near the place where the first had been, and crossed with his army. But, as before, the Suevi and Sicambrians drew back among the forest-covered hills along the Weser river, and only the small and peaceful tribe of the Ubii remained in their homes. The latter offered their submission to Cæsar, and agreed to furnish him with news of the movements of their warlike countrymen, in return for his protection. When another revolt of the Celtic Gauls took place, the following year, German mercenaries, enlisted among the Ubii, fought on the Roman side and took an important part in the decisive battle which gave Vercingetorix, the last chief of the Gauls, into Cæsar's hands. He was beheaded, and from that time the Gauls made no further effort to throw off the Roman yoke. They accepted the civil and military organization, the dress and habits, and finally the language and religion of their conquerors. The small German tribes in Alsatia and Belgium shared the same fate: their territory was divided into two provinces, called Upper and Lower Germania by the Romans. The vast region inhabited by the independent tribes, lying between the Rhine, the Vistula, the North Sea and the Danube, was thenceforth named _Germania Magna_, or "Great Germany." Cæsar's renown among the Germans, and probably also his skill in dealing with them, was so great, that when he left Gaul to return to Rome, he took with him a German legion of 6,000 men, which afterwards fought on his side against Pompey, on the battle-field of Pharsalia. The Roman agents penetrated into the interior of the country, and enlisted a great many of the free Germans who were tempted by the prospect of good pay and booty. Even the younger sons of the chiefs entered the Roman army, for the sake of a better military education. [Sidenote: 15 B. C. THE EXPEDITIONS OF DRUSUS.]