In dealing with a madmen hellbent on playing invader-king, Julius Caesar decided to go to war to preserve a more favorable peace.
Immediately after his victory over the Helvetii in Gaul, Julius Caesar was informed of the encroaching presence of a German army led by Ariovistus into Sequani territory (modern: Franche-Comte, France). The Sequani and the Arverni, two tribes of Gaul, had invited these Germans to join them in conquest against the Aedui tribe (whom Diviciacus led) for dominance of Gaul.
Germans had constantly been invading Gaul already, so they readily accepted this invitation. And so it quickly turned to be a disastrous mistake for the Sequani and Arverni. Ariovistus and his stream of emigrating Germans took a liking to the farmland, wealth, and civilization of Gaul, for the Germans were semi-nomadic, known to sleep without a roof over their heads and kept no practice of farming or constructing shelters. So many Germans, approximately 144,000, moved in that they came to occupy nearly one third of Gaul. And to boot, this was some of Gaul’s best, most arable land. They forcefully expelled the native population and replaced it with their own kin from over the River Rhine.
Led by the Aedui, many Gallic tribes took up arms and marched eastward against this invasion but were defeated when, unable to find Ariovistus who was hiding his forces in marshland, turned back and were caught off guard by Ariovistus’ devastating surprise attack. This single event gave Ariovistus the gall to proclaim himself conqueror of that swath of land by virtue of war, so he demanded hostages, slaves, and tribute from the Gauls there. Faced with a reign of terror, the Gauls begged Julius Caesar with tearful pleadings to drive the Germans away back over the Rhine.
Caesar had prior been friendly to Ariovistus about ten years earlier when, serving as consul of Rome, he recognized Ariovistus’s kingship and named him a friend of Rome. However, considering the warlike tendency of the Germans and the potential loss of that good land in Gaul, which Caesar had his eyes on claiming for Rome, Caesar heard the Gallic cries for help and moved north from his station in Hither Gaul (modern: Northern Italy) to meet Ariovistus.
Ariovistus refused to go to Caesar out of fear for his safety, so he said he would meet Caesar only if Caesar would come to him. Caesar obliged and gathered his six legions.
Word came that Ariovistus was advancing toward a valuable city named Vesontio east of Helvetii territory (modern: Switzerland). So, Caesar set upon it with a series of forced marches day and night to reach the city first because it was well fortified, naturally guarded on a hilltop enclosed by an encircling river, and possessed an abundance of supplies and resources handy for war. From there, Caesar conducted communications by messenger with Ariovistus and arranged for the two of them to meet unaccompanied by their armies.
They met on top of a lone hill. Each leader brought with him some cavalry, which stayed at the bottom of the hill.
The discussion was fruitless. Ariovistus’s insanity was marked by his inability to remember his own statements and promises. He would describe Caesar as being both his friend and enemy in the same breath. And he would declare peace and war at the same time. Caesar had come with a reasonable offer of peace: Ariovistus should return his imprisoned Gallic hostages and slaves back to their homes, cease demanding tax and tribute from Gallic tribes, and, if not return to Germany, at least stop migrating more Germans into Gaul — so allowing him to keep the people already settled to stay and live in peace. A fair deal by all means for both the Germans and the Gauls.
Ariovistus refused this treaty and stood by his claim of total dominion over his new land. First, he argued, he was invited there by the Gauls, specifically the Sequani and Arverni. Second, his right to exact tribute and hostages was secured by his victory in war over them. And if Caesar would deprive him of that ruthless sovereignty, which Ariovistus repeated was his by right of war, then Caesar would be considered his enemy.
At this point, one of Caesar’s guards (who was a member of his favored Tenth Legion mounted on horse requisitioned from auxiliary Gallic cavalry) informed Caesar that Ariovistus’s men were throwing stones and darts at them. So, Caesar ended the meeting, reasoning that taking the moral high ground against such an illogical barbarian who could not even abide by his own proposed rules for a peaceful discussion (it was Ariovistus’s idea that their be no combat at the meeting), would quicker justify military action and make him look good in the eyes of Rome and Gaul.
This rhetorical positioning was crucial, you see, because fear was spreading like a scourge within Caesar’s camp. Rumors of the Germans’ fierceness, scary eyes, large stature, and skill with weaponry spread from the mouths of the recently beaten Gauls to the ears of Caesar’s new-to-the-area soldiers, causing morale to drop.
Caesar, in a speech, then roused the spirits of his men by first calling out the pretenses of their sudden gripes and concerns over a shortage of food, unfamiliarity with the forested terrain, and lack of business being there to help the Gauls as cowardice and fear of the purported might and ferociousness of the Germans. To this, he scolded them lightly for doubting his competence in military strategy, his past record of military success, and for forgetting their place as soldiers who were supposed to take orders from their leaders without question. Then, he reminded them of past Roman victories against Germans; that the Helvetii who they just recently defeated were known to be stronger than Germans; and that Ariovistus’s recent victory over the Gauls was based only on surprise, not might. Therefore, there was no need to worry that Romans could not beat Germans. His speech was effective.
Ariovistus again sent messengers to ask Caesar to pick up where negotiations had left off, if not with himself than at least with a representative from Caesar’s staff. Tired of Ariovistus’s insufferable arrogance and impertinence, Caesar sent two of his trusted men instead.
Meanwhile, Caesar, with the help of the Aeduian Diviciacus, found a route through open country to move his army closer to Ariovistus’s.
When Caesar’s two men arrived at Ariovistus’s camp, Ariovistus accused them of being spies and put them in chains as prisoners.
What else must be made for pretext for war? If Ariovistus claimed conquest by means of war, then by war he should have it so.
Encamped nearby, Caesar daily put his army out in formation for battle, inviting Ariovistus to fight for the power he claimed to have. Ariovistus did naught but reposition his camp to intercept the grain supply Caesar had been receiving from neighboring tribes. Caesar then split his troops and formed another fortification on the other side of Ariovistus’s new camp. This was done by Caesar with two legions and an auxiliary force of Gauls while he kept his four main legions in the first camp. What then? One day, as Caesar was displaying his main forces ready for battle, no attack came, so at noon he had them return to camp. Then, Ariovistus launched a cavalry attack on Caesar’s second, smaller camp.
The assault was relatively minor in terms of casualties, but it was a boon for the Romans. In capturing some Germans prisoners, Caesar was able to learn why Ariovistus had been refusing to engage in battle. They divulged that German matrons who, through a form of mysticism and fortune-telling called cleromancy, were informing Ariovistus that a battle against the Romans at any time before the upcoming New Moon would be a sure defeat. So, with this information, Caesar prepared to assault Ariovistus’s camp at once.
Seeing the Romans approach their camp so offensively, the Germans had no choice but to put up some defenses. They lined up all their carts and wagons to form a sort of wall behind which they would not retreat. To further prevent any inclination of running away, all of their German women stood on this wall with interlocking arms and wailed shrill shouts and war cries for their men.
The battle commenced at such close quarters that the typical Roman strategy of throwing javelins then advancing with sword was nullified. So, casting aside their javelins, the Romans simply advanced by sword. The Germans huddled themselves up in tight masses.
Caesar was positioned on the Roman right flank and readily defeated the German opposition at that end. But on the left flank, the Romans were having difficulty enduring a strong German contingency until a young Roman cavalry commander, Publius Crassus the younger, swooped in and broke the German line there, allowing the Romans to secure the battle victoriously! Many Germans tried to flee finding their only escape to be over the River Rhine. Among those cowards was Ariovistus himself who was able to find a small boat to cross over while leaving his wives behind.
Caesar himself rescued one of those men who were put into chains days earlier when sent over to negotiate with Ariovistus. Rescuing his personal friend brought Caesar even greater pleasure in the victory.
As news of their defeat spread, the rest of the Germans following Ariovistus fled and returned to the their original homelands.
Thus, in one summer, in 58 B.C., Julius Caesar won two campaigns in eastern Gaul: one against the Helvetii and one against the Germans. In doing so, he introduced himself as the prominent peacekeeper and dominant military force in Gaul. This was a position he would eventually use to provincialize new territories. Although Rome’s Senate wanted to keep peace with a free Gaul, Caesar saw Rome’s interest better served by letting her eagle soar over the region. And, as his eventual megalomania would later be revealed, the glory of military victory and territorial expansion was enough to drive the man onward.