When the main Roman army advanced, and began to threaten the wagon citadel of the Germans, Ariovistus determined to give battle. The battle itself was won through the superior discipline of the Romans; once during its progress the left wing was in danger, but it was saved by the prompt action of the younger Crassus, who was in command of the cavalry. Cæsar with the right wing carried all before him. As to the numbers engaged, it was Napoleon’s opinion that the Germans were not stronger than Cæsar; the probability is that they were weaker. Ariovistus’ whole army, though with it he controlled a large part of Gaul, need not have been more than 20,000 men. They were, of course, a better trained fighting force than anything the Gallic tribes could create, and it was not difficult, using the divisions among the Gauls, to establish an effective overlordship with a small, well-disciplined army. Apparently the bulk of the German army was destroyed; Ariovistus, however, succeeded in making his escape beyond the Rhine. The defeat of the Germans had important consequences; before the opening of the campaign against Ariovistus, news had come from the north that the Suevi, an important German tribe, were about to move across the Rhine. The knowledge of the fate of Ariovistus forced them back again into the depths of Germany. During the winter Cæsar crossed the Alps to attend to the administration of the Cisalpine province, leaving his troops quartered in Gaul under the command of his trusted lieutenant, Labienus. He raised two new legions, and when he returned northward it was already plain that the pacification of the country was far from complete. The Gauls feared the expansion of Roman power, and there were rumors of an uprising to be led by the tribes of the Belgæ. Cæsar marched directly to the danger spot, and taking advantage of tribal jealousies, induced the Remi, whose territory lay between the Maas, the Oise, and the Maine, to accept the alliance and protectorate of Rome. (57 B.C.) This was a wise move, for it was clear from reports on the spot that the whole Belgic confederacy, representing the most warlike of the Gallic tribes, were up in arms. The fate of Ariovistus, the year before, had shown that the only way to resist the extension of Roman rule in Gaul was by tribal combination. The Belgæ thoroughly realized their danger, and when Cæsar passed their frontiers, they opposed him with a large allied army composed of contingents of all the neighboring peoples.