In the winter between 698 and 699, the Usipetes and the Tencteri, peoples of German origin, to escape the oppression of the Suevi, passed the Rhine not far from its mouth, towards Xanten and Clèves. They numbered 400,000, of all ages and both sexes; they sought new lands to settle in, and, in the spring of 699, the head of the emigration had already reached the country where now stand Aix-la-Chapelle and Liége. Cæsar, alarmed at this event, starts for the army sooner than usual, proceeds to Amiens, there assembles his troops, and finds the Gaulish chiefs profoundly shaken in their fidelity by the approach of these new barbarians, whose co-operation they hope to obtain. He confirms their feeling of duty, obtains a contingent of cavalry, marches to encounter the Usipetes and the Tencteri, and arrives on the Meuse, which he crosses at Maëstricht. These latter, on hearing of the approach of the Roman army, had concentrated in Southern Gueldres. Established on the river Niers, in the plains of Goch, they send a deputation to Cæsar, who had arrived near Venloo, to ask him not to attack them, but to allow them to keep the lands they had conquered. The Roman general refuses, and continues his march. After new conferences, the object of which, on the part of the Germans, was to give their cavalry, sent beyond the Meuse, time to return, a truce of one day is accepted. Cæsar declares, nevertheless, that he will advance to Niers. Suddenly, however, his vanguard is treacherously attacked in its march and routed by the German cavalry; he then believes himself freed from his engagements; and when next day the deputies come to excuse this perfidious aggression, he has them arrested, falls unexpectedly on the camp of the Germans, and pursues them without remission to the confluence of the Rhine and the Meuse (towards the place occupied now by Fort Saint-André), where these unfortunate people nearly all perish. In the sequel of this exploit, which brought him little glory, and in which doubt has been thrown on his good faith, Cæsar resolved to cross the Rhine, on the pretence of claiming from the Sicambri the cavalry of the Usipetes and the Tencteri, who had taken refuge among them, but, in reality, to intimidate the Germans, and make them abandon the practice of seconding the insurrections in Gaul. He therefore proceeded up the valley of the Rhine, and arrived at Bonn, opposite the territory of the Ubii, a people which had already solicited his alliance and support against the Suevi. He caused to be built in ten days a bridge of piles, which he crossed with his troops, but he did not penetrate far into Germany: unable to come up with either the Sicambri or the Suevi, who had withdrawn into the interior of their country, he re-crossed to the left bank, and caused the bridge to be broken. [Sidenote: First Descent in England.]