Beginning of the Wars – campaign against the Helvetii The
Helvetii were a confederation of about five related Gallic tribes that lived on the Swiss plateau, hemmed in by the mountains and the rivers Rhine and
Rhône. They had come under increased pressure from Germanic tribes to the north and the east and began planning for a migration around 61 BC. They intended to travel across Gaul to the
Saintonge region of modern France, a route that would have taken them around the Alps and through lands of the Aedui (a Roman ally) into the Roman province of Transalpine Gaul. As word of the migration spread, neighboring tribes grew concerned, and Rome sent ambassadors to several tribes to convince them not to join the Helvetii. Concern grew in Rome that the
Germanic tribes would fill in the lands vacated by the Helvetii. The Romans much preferred the Gauls to the Germanic tribes as neighbors. One of the consuls of 60 (
Metellus) and one of 59 BC (Caesar) both wanted to lead a campaign against the Gauls, though neither had a
casus belli at the time. On 28 March in 58 BC, the Helvetii began their migration, bringing along all their peoples and livestock. They burned their villages and stores to ensure the migration could not be reversed. Upon reaching Transalpine Gaul, where Caesar was governor, they asked permission to cross the Roman lands. Caesar entertained the request but ultimately denied it. The Gauls turned north instead, entirely avoiding Roman lands. The threat to Rome was seemingly over, but Caesar led his army over the border and attacked the Helvetii unprovoked. So began what historian Kate Gilliver describes as "an aggressive war of expansion led by a general who was seeking to advance his career". Caesar's consideration of the Gallic request to enter Rome was not indecision, but a play for time. He was in Rome when news of the migration arrived, and he rushed to Transalpine Gaul, raising two legions and some auxiliaries along the way. He delivered his refusal to the Gauls, and then promptly returned to Italy to gather the legions he had raised on his previous trip and three veteran legions. Caesar now had between 24,000 and 30,000 legionary troops, and some quantity of auxiliaries, many of whom were themselves Gauls. He marched north to the river
Saône, where he caught the Helvetii in the middle of crossing. Some three-quarters had crossed; he slaughtered those who had not. Caesar then crossed the river in one day using a
pontoon bridge. He followed the Helvetii, but chose not to engage in combat, waiting for ideal conditions. The Gauls attempted to negotiate, but Caesar's terms were draconian (likely on purpose, as he may have used it as another delaying tactic). Caesar's supplies ran thin on 20 June, forcing him to travel towards allied territory in
Bibracte. While his army had easily crossed the Saône, his supply train still had not. The Helvetii could now outmaneuver the Romans and had time to pick up
Boii and
Tulingi allies. They used this moment to attack Caesar's rearguard.
Battle of Bibracte In the ensuing
Battle of Bibracte, the Gauls and Romans fought for the better part of the day. After a hotly contested battle, the Romans eventually gained victory. Caesar had set up his legions on the slope of a hill, which put the Gauls at a disadvantage as they had to fight uphill. The Helvetii started the battle with a probable
feint, which the Romans easily repulsed. However, the Boii and Tulingi then outmaneuvered the Romans and attacked their right flank. At this point, the Romans were surrounded. A heated battle ensued. The men in the legion's last line were ordered to turn their backs around. They now fought on two fronts instead of just being attacked in the rear, which Gilliver describes as a brilliant tactical decision. Eventually, the Helvetii were routed and fled. The Romans chased the now outnumbered Boii and Tulingi back to their encampments, killing the fighters as well as slaying the women and children. Caesar's army rested for three days to tend to the wounded. They then gave chase to the Helvetii, who surrendered. Caesar ordered them back on their lands to provide a buffer between Rome and the even more feared Germanic tribes. In the captured Helvetian camp Caesar claims that a census written in Greek was found and studied: of a total of 368,000 Helvetii, of whom 92,000 were able-bodied men, only 110,000 survivors remained to return home. Historians believe the total was likely between 20,00050,000, with the excess exaggerated by Caesar for propaganda purposes. (See
historiography section below for a detailed accounting). Bibracte, then the commercial hub of the Gallic Aedui tribe, would again play a crucial role during the Gallic uprising of 52 BC. Vercingetorix himself met with other Gallic leaders there to plot the rebellion against Caesar and the Romans. After Vercingetorix's revolt failed, Bibracte was slowly abandoned for other more prosperous settlements nearby.
Campaign against the Suebi Caesar then turned his attention to the Germanic Suebi, whom he also wished to conquer. The Senate had declared Ariovistus, king of the Suebi, a "friend and ally of the Roman people" in 59 BC, so Caesar needed a convincing
casus belli to betray the Suebi. He found his excuse following victory over the Helvetii. A group of Gallic tribes congratulated him and sought to meet in a general assembly, hoping to leverage the Romans against other Gauls.
Diviciacus, the head of the Aeduan government and spokesmen for the Gallic delegation, expressed concern over Ariovistus' conquests and for the hostages he had taken. Not only did Caesar have a responsibility to protect the longstanding allegiance of the Aedui, but this proposition presented an opportunity to expand Rome's borders, strengthen loyalty within Caesar's army and establish him as the commander of Rome's troops abroad. With the attack of the
Harudes (an apparent Suebi ally) on the Aedui and the report that a hundred clans of Suebi were trying to cross the Rhine into Gaul, Caesar had the justification he needed to wage war against Ariovistus in 58 BC. Learning that Ariovistus intended to seize
Vesontio, the largest Sequani town, Caesar marched towards it and arrived before Ariovistus. Ariovistus sent emissaries to Caesar requesting a meeting. They met under a truce at a knoll outside of town. The truce was violated when Germanic horsemen edged towards the knoll and threw stones at Caesar's mounted escort. Two days later, Ariovistus requested another meeting. Hesitant to send senior officials, Caesar dispatched
Valerius Procillus, his trusted friend, and Caius Mettius, a merchant who had traded successfully with Ariovistus. Insulted, Ariovistus threw the envoys in chains. Ariovistus marched for two days and made camp behind Caesar, thus cutting off his communication and supply lines with the allied tribes. Unable to entice Ariovistus into battle, Caesar ordered a second smaller camp built near Ariovistus' position. The next morning Caesar assembled his allied troops in front of the second camp and advanced his legions in towards Ariovistus. Each of Caesar's five legates and his
quaestor were given command of a legion. Caesar lined up on the right flank. Ariovistus countered by lining up his seven tribal formations. Caesar was victorious in the ensuing battle due in large part to the charge made by
Publius Crassus, son of Marcus Crassus. As the Germanic tribesmen began to drive back the Roman left flank, Crassus led his cavalry in a charge to restore balance and ordered up the cohorts of the third line. As a result, the whole Germanic line broke and began to flee. Caesar claims that most of Ariovistus' one-hundred and twenty thousand men were killed. He and what remained of his troops escaped and crossed the Rhine, never to engage Rome in battle again. The Suebi camping near the Rhine returned home. Caesar was victorious. In one year he had defeated two of Rome's most feared enemies. After this busy campaigning season, he returned to Transalpine Gaul to deal with the non-military aspects of his governorship. At this point it is possible he had already decided he would conquer all of Gaul.
57 BC: Campaigns in the east Caesar's stunning victories in 58 BC had unsettled the Gallic tribes. Many rightly predicted Caesar would seek to conquer all of Gaul, and some sought alliance with Rome. As the campaigning season of 57 BC dawned, both sides were busy recruiting new soldiers. Caesar set off with two more legions than the year before, with 32,000 to 40,000 men, along with a contingent of auxiliaries. The exact number of men the Gauls raised is unknown, but Caesar claims he would fight 200,000. Intervening again in an intra-Gallic conflict, Caesar marched against the
Belgae tribal confederation, who inhabited the area roughly bounded by modern-day
Belgium. They had recently attacked a tribe allied with Rome and before marching with his army to meet them, Caesar ordered the
Remi and other neighboring Gauls to investigate the Belgae's actions. The Belgae and the Romans encountered each other near
Bibrax. The Belgae attempted to take the fortified
oppidum (main settlement) from the Remi but were unsuccessful and chose instead to raid the nearby countryside. Each side tried to avoid battle, as both were short on supplies (a continuing theme for Caesar, who gambled and left his baggage train behind several times). Caesar ordered fortifications built, which the Belgae understood would give them a disadvantage. Instead of making battle, the Belgic army simply disbanded, as it could be re-assembled easily. Caesar realized an opportunity was presenting itself: if he could beat the men from the army home, he could take their lands with ease. His armies' travel speed proved to be a crucial aspect of his ensuing victories. He rushed to the Belgic
Suessiones'
oppidum at what is now
Villeneuve-Saint-Germain and laid siege to it. The Belgic army nullified Caesar's advantage by sneaking back into the city under cover of darkness. The Roman siege preparations proved to be the decisive factor: grand Roman-style siege warfare was unknown to the Gauls, and the might of the Romans' preparations drove the Gauls to surrender promptly. This had a ripple effect: the nearby
Bellovaci and
Ambiones surrendered immediately afterward, realizing the Romans had defeated a powerful army without any combat. Not all the tribes were so cowed though. The
Nervii allied with the
Atrebates and
Viromandui, and planned to ambush the Romans. The ensuing
battle of the Sabis was nearly a humiliating defeat for Caesar, and the Roman victory was very hard-won.
Nervii ambush: the battle of the Sabis The Nervii set up an ambush along the river
Sambre, lying in wait for the Romans who arrived and started setting up camp. The Romans detected the Nervii, and the battle began with the Romans sending a light cavalry and infantry force across the river to keep the Nervii at bay while the main force fortified its camp. The Nervii easily repulsed the attack. In an uncharacteristic move for Caesar, he made a serious tactical error by not setting up an infantry screen to protect the entrenching force. The Nervii took ample advantage of this, and their entire force crossed the river quickly and caught the Romans off-guard and unprepared. As the battle began, two legions had not even arrived, whereas the Nervii had at least 60,000 fighters. The reserve legions were stuck at the end of the column, back, with the 8,000 animals of the baggage train. However, because the soldiers could operate independently of the train, the forwards legions were still ready for battle. The Romans' superior discipline and experience came in use and they quickly formed lines of battle. Their center and left wings were successful and chased the Atrebates across the river. To the tribes' advantage, this exposed the half-built camp, and they took it easily. To make matters worse for the Romans, the right wing was in serious trouble. It had been outflanked, its line of battle had become too tight to swing a sword, and multiple officers were dead. The situation was so critical Caesar took up his shield and joined the front line of the legion. His mere presence greatly increased morale, and he ordered his men to form a defensive square to open the ranks and protect them from all sides. What turned the tide of battle was Caesar's reinforcements, the X legion which returned from chasing the Atrebates, and the two straggler legions that finally arrived. The strong stand by the X legion and the timely arrival of reinforcements enabled Caesar to regroup, redeploy and eventually repulse the Nervii once the Atrebates and Viromandui were put to flight. Caesar's cockiness had nearly ended in defeat, but the legions' experience combined with his personal role in combat turned a disaster into an incredible victory. The Belgae were broken, and most of the Germanic tribes offered submission to Rome. The end of the campaigning season saw Caesar conquer tribes along the Atlantic coast, and deal with the
Atuatuci, who were allies of the Nervii but had broken the terms of surrender. Caesar punished the Atuatuci by selling 53,000 of them into slavery. By law, the profits were Caesar's alone. He saw a minor setback towards winter as he sent
one of his officers to the
Great St Bernard Pass, where local tribes fought back fiercely; he abandoned the campaign. But overall, Caesar had seen monumental success in 57 BC. He had accumulated great wealth to pay off his debts and increased his stature to heroic levels. Upon his return, the senate granted him a 15-day thanksgiving (
supplicatio), longer than any before. His political reputation was now formidable. Again, he returned to Transalpine Gaul for the winter to see to the civil affairs of the province. He wintered his troops in northern Gaul, where the tribes were forced to house and feed them.
56 BC: Campaign against the Veneti minted by
Decimus Brutus in 48 BC, recalling his service in Gaul. The obverse features the head of
Mars, and the reverse shows Gallic
carnyces and shields. The Gauls were embittered at being forced to feed the Roman troops over the winter. The Romans sent out officers to requisition grain from the
Veneti, a group of tribes in northwest Gaul, but the Veneti had other ideas and captured the officers. This was a calculated move: they knew this would anger Rome and prepared by allying with the tribes of
Armorica, fortifying their hill settlements, and preparing a fleet. The Veneti and the other peoples along the Atlantic coast were versed in sailing and had vessels suitable for the rough waters of the Atlantic. By comparison, the Romans were hardly prepared for naval warfare on the open ocean. The Veneti also had sails, whereas the Romans relied on oarsmen. Rome was a feared naval power in the Mediterranean, but there the waters were calm, and less sturdy ships could be used. Regardless, the Romans understood that to defeat the Veneti they would need a fleet: many of the Venetic settlements were isolated and best accessible by sea.
Decimus Brutus was appointed
prefect of the fleet. Caesar wished to sail as soon as the weather permitted and ordered new boats and recruited oarsmen from the already conquered regions of Gaul to ensure the fleet would be ready as soon as possible. The legions were dispatched by land, but not as a single unit. Gilliver regards this as evidence that Caesar's claims the prior year that Gaul was at peace were untrue, as the legions were apparently being dispatched to prevent or deal with rebellion. A cavalry force was sent to hold down the Germanic and Belgic tribes. Troops under Publius Crassus were sent to
Aquitania, and
Quintus Titurius Sabinus took forces to Normandy. Caesar led the remaining four legions overland to meet up with his recently raised fleet near the mouth of the river
Loire. The Veneti held the upper hand for much of the campaign. Their ships were well-suited to the region, and when their hill forts were under siege, they could simply evacuate them by sea. The less sturdy Roman fleet was stuck in harbor for much of the campaign. Despite having the superior army and great siege equipment, the Romans were making little progress. Caesar realized that the campaign could not be won on land and halted the campaign until the seas calmed enough for the Roman vessels to be most useful.
Battle of Morbihan At last, the Roman fleet sailed, and encountered the Venetic fleet off the coast of Brittany near
Quiberon Bay. They engaged in a battle that lasted from late in the morning until sundown. On paper, the Veneti appeared to have the superior fleet. Their ships' sturdy oak beam construction meant they were effectively immune to ramming, and their high-profile protected their occupants from projectiles. The Veneti had some 220 ships, although Gilliver notes many were likely not much more than fishing boats. Caesar did not report the number of Roman ships. The Romans had one advantage—
grappling hooks. These allowed them to shred the rigging and sails of the Venetic ships that got close enough rendering them inoperable. The hooks also allowed them to pull ships close enough to board. The Veneti realized the grappling hooks were an existential threat and retreated. However, the wind dropped, and the Roman fleet (which did not rely on sails) was able to catch up. The Romans could now use their superior soldiers to board ships
en masse and overwhelm the Gauls at their leisure. Just as the Romans had beaten the superior forces of
Carthage in the
First Punic War by using the
corvus boarding device, a simple technological advantage—the grappling hook—allowed them to defeat the superior Venetic fleet. Conquering Gaul enabled further expansion of the Empire into Northwestern Europe.
Augustus would push into Germania and reach the
Elbe, though settled on the Rhine as the imperial border following the disastrous
Battle of the Teutoburg Forest. In addition to facilitating the conquest of parts of Germania, the
Roman conquest of Britain led in 43 AD by
Claudius also built on Caesar's invasions. The Roman hegemony would last, with only
one interruption, until the
Crossing of the Rhine in 406 AD. == Historiography ==