III. After so brilliant a success, Cæsar, to secure the results, considered it a measure of importance to cross the Rhine, and so seek the Germans in their homes. For this purpose, he must choose the point of passage where the right bank was inhabited by a friendly people, the Ubii. The study of this and the following campaigns leads us to believe that this was Bonn.[308] From the field of battle, then, he proceeded up the valley of the Rhine; he followed a direction indicated by the following localities: Gueldres, Crefeld, Neuss, Cologne, and Bonn. (_See Plate 14._) Above all, it was Cæsar’s intention to put a stop to the rage of the Germans for invading Gaul, to inspire them with fears for their own safety, and to prove to them that the Roman army dared and could cross a great river. He had, moreover, a plausible motive for penetrating into Germany--the refusal of the Sicambri to deliver up to him the cavalry of the Usipetes and Tencteri, who had taken refuge among them after the battle. The Sicambri had replied to his demand, that the empire of the Roman people ended with the Rhine, and that beyond it Cæsar had no further claims. At the same time, the Ubii, who alone of the peoples beyond the Rhine had sought his alliance, claimed his protection against the Suevi, who were threatening them more seriously than ever. It would be a sufficient guarantee for their safety, they said, to show himself on the right bank of the Rhine, so great was the renown of the Roman army among even the most remote of the German nations, since the defeat of Ariovistus and the recent victory; and they offered him boats for passing the river. Cæsar declined this offer. It did not appear to him worthy of the dignity of himself or of the Roman people to have recourse to barbarians, and he judged it unsafe to transport the army in boats. Therefore, in spite of the obstacles presented by a wide, deep, and rapid river, he decided on throwing a bridge across it.