It should be known that among the Germans during the time of the late Roman Republic circa 50 B.C., the Suebi tribe were the largest and most powerful. With force and size they dominated other Germans, received tribute from them, and held them in subjugation. Some tribes feared them and often fled from them over the Rhine and into Gaul. The Ubii was one such Germanic tribe. Populous and relatively civilized as they were, for they welcomed trade with Gaul, they could not stop the harassment from the Suebi. They were also friendly with Caesar. Some tribes, however, acted like thugs for the Suebi.
The Suebi domain lied along the Danube River and extended north into central Germany (modern: Hesse, Germany). On its western borders lived the Ubii (modern: Rhineland, Germany) and the Tencteri and Usipetes tribes who dwelled along the Rhenus River (modern: Rhine River, Westphalia and Lower Saxony, Germany). The Tencteri and the Usipetes were among those Germans tribes who had been invited by the Belgae to join their armed resistance against the Romans. However, these groups were not friendly allies. They would frequently cross the Rhine and raid Gaul and Belgae. On one such occasion, which you shall learn of now, in 55 B.C., the Tencteri and Usipetes entered Belgae territory and terrorized its inhabitants, displacing the Belgic tribe of the Menapii (modern: Flanders, Belgium).
As winter melted, Caesar found himself in the oft-occurring situation of hearing about a German invasion into Gaul. Untrusting now of how often the Gauls rescinded their loyalty to Rome and how prone they were to surrender to whoever was the immediate threat to them, Caesar moved his army toward the those regions being encroached on by the Germans south along the whole extent of the Rhine River within Belgae territory.
Caesar sent messengers ahead in an attempt to diplomatically sway the Germans back over the Rhine where, he promised, they should be afforded peaceful resettlement among the Ubii, the German tribe friendly to Caesar. He recognized that the Suebi were bullying them and that they could look to Rome for protection, but they should not terrorize the Belgae. To this, the Germans denounced Roman imperialism as having no right in the affairs of the land beyond the Rhine River, and that only the Suebi could give them commands. These discussions took place over a series of days, during which Caesar told the Tencteri and Usipetes to return to Germania and the Germans requested that Caesar quit his march toward them. Of course, Caesar did not oblige and continued marching toward the Rhine. Aware that German cavalry was sweeping through some of the tribelands and raiding their supplies, Caesar pushed on without a moment’s hesitation, knowing furthermore that a greater conflict would be imminent and that allowing the two Germans tribes to unite their army en masse would prove to be a considerable challenge for the Romans.
Although the Germans had asked for peace until they could finish brokering their negotiations, they attacked the Roman cavalry on sight when they saw Caesar arrive. The attack caught the Roman cavalry off guard, though 5,000 horsemen strong, because the Germans had asked for peace. So this surprise, combined with the German cavalry tactic of riding in on horse back, jumping off, and attacking the horse of the enemy cavalry, thereby cutting the mounted horseman of his steed, resulted in the death of some 74 Roman cavalry causing the rest to run back to the Roman camp.
Some German chiefs then came to Caesar asking him to forgive their people for attacking his cavalry and to also negotiate peace in person.
Caesar cheered at their arrival, greeting them with shackles and imprisoning them in chains. Then, he moved his whole army of approximately 30,000 men up to the German camp which had by now formed consisting of 430,000 men, women, and children. Inexplicably, they made quick work of sweeping up this camp. The Roman attack was such a surprise because they marched so quickly that the Germans sooner expected their chiefs to return than to see the whole of the Roman army storm upon them. Reportedly, not one Roman died. So terrified, the surviving Germans attempted to flee across the Rhine River rather subjecting themselves to its torrents than to the torments of defeat by Roman hand. And thus, another quick campaign against the Germans was done. And it was by the strategy of preemptive strike that a potentially major and costly war was won.
In the aftermath of this victory, the Ubii tribe invited Caesar to cross the Rhine and display his dominance and the Roman standard in Germany, hoping that a show of their siding with Rome would protect them from future harassment from other Germans like the Suebi. So, in ten days, Caesar’s legions built a bridge, forty feet wide, along the River Rhine—a strong and wide river impassable by foot. The feat, a marvel of Roman engineering, was enough to cause many German tribes to offer hostages and friendships in exchange for peace with Caesar. The Suebi called its allies to abandon their homes and form up a war force in a distant forest out of fear of the Romans. Caesar sacked and burned the territory of the Sugambri—a tribe in cahoots with the recently defeated Tencteri and Usipetes—(modern: northern Rhineland, Germany) who had fled in fear at his coming.
Pleased with the effect he had accomplished in only three week’s time in Germany, Julius Caesar destroyed his bridge and returned to Gaul at the end of that same summer in 55 B.C.