Gallic Wars

The Romans respected and feared the Gallic tribes. In 390 BC, the Gauls had sacked Rome, which left an existential dread of barbarian conquest the Romans never forgot. In 121 BC, Rome conquered a group of southern Gauls, and established the province of Transalpine Gaul in the conquered lands. Only 50 years before the Gallic Wars, in 109 BC, Italy had been invaded from the north and saved by Gaius Marius only after several bloody and costly battles. Around 63 BC, when a Roman client state, the Gallic Arverni, conspired with the Gallic Sequani and the Germanic Suebi nations east of the Rhine to attack the Gallic Aedui, a strong Roman ally, Rome turned a blind eye. The Sequani and the Arverni defeated the Aedui in 63 BC at the Battle of Magetobriga.

Rising politician and general Julius Caesar was the Roman commander and agonist of the war. As a result of the financial burdens of being consul (the highest office in the Roman Republic) in 59 BC, Caesar had incurred significant debts. To strengthen Rome's position among the Gauls, he had paid substantial money to Ariovistus, king of the Suebi, to cement an alliance. 

Caesar had four veteran legions under his direct command initially: Legio VII, Legio VIII, Legio IX Hispana, and Legio X. As he had been governor of Hispania Ulterior in 61 BC and had campaigned successfully with them against the Lusitanians, Caesar knew most, perhaps even all, of the legions personally. 

His ambition was to conquer and plunder some territories to get himself out of debt. It is possible that Gaul was not his initial target, he may have been planning a campaign against the Kingdom of Dacia in the Balkans instead. However, a mass migration of Gallic tribes in 58 BC provided a convenient casus belli, and Caesar prepared for war.

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 west coast, 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. The consuls of 60 (Metellus) and 59 BC (Caesar) both wanted to lead a campaign against the Gauls, though neither had a casus belli at the time.

On the 28th of 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 had still 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.

Informed by deserters from the allied auxiliary cavalry of Lucius Aemilius (the commander of the cavalry), the Helvetii decided to harass Caesar's rear guard. When Caesar observed this, he sent his cavalry to delay the attack. He then placed the Seventh (Legio VII Claudia), Eighth (Legio VIII Augusta), Ninth (Legio IX Hispana), and Tenth legions (Legio X Equestris), organized in Roman fashion (triplex acies, or "triple battle order"), at the foot of a nearby hill, the top of which he occupied himself, along with the Eleventh (Legio XI Claudia) and Twelfth (Legio XII Fulminata) Legions and all his auxiliaries. His baggage train was assembled near the summit, where it could be guarded by the forces there.

Having driven off Caesar's cavalry and with their own baggage train secured, the Helvetii engaged "In the seventh hour", approximately noon or one o'clock. According to Caesar, his hilltop battle line easily threw back the onslaught by using pila (javelins/throwing spears). The Roman legionaries then drew swords and advanced downhill wading into their opponents. Many Helvetii warriors had pila sticking out of their shields and threw them aside to fight unencumbered, but this also made them more vulnerable. The legions drove the Helvetii back toward the hill where their baggage train sat.

While the legions pursued the Helvetii across the plain between the hills, the Boii and the Tulingi arrived with fifteen thousand men to assist the Helvetii, flanking the Romans on one side. At that point, the Helvetii returned to the battle in earnest. When the Tulingi and the Boii started circumventing the Romans, Caesar regrouped his third line to resist the assault of the Boii and Tuligni, keeping his primary and secondary committed to chasing the Helvetii.

The battle lasted many hours into the night, until the Romans finally took the Helvetic baggage train, capturing both a daughter and a son of Orgetorix. According to Caesar, 130,000 enemies escaped, of which 110,000 survived the retreat. Unable to pursue on account of battle wounds and the time it took to bury the dead, Caesar rested three days before he followed the fleeing Helvetii. These, in turn, had managed to reach the territory of the Lingones within four days of the battle. Caesar warned the Lingones not to assist them, prompting the Helvetii and their allies to surrender.

In 61 BC, Ariovistus, chieftain of the Suebi tribe and a king from the Germanic peoples, resumed the tribe's migration from eastern Germania to the Marne and Rhine regions. Despite this migration encroaching on Sequani land, they sought Ariovistus' allegiance against the Aedui. In 61 BC, the Sequani rewarded Ariovistus with land following his victory at the Battle of Magetobriga. Ariovistus settled the land with 120,000 of his people. When 24,000 Harudes joined his cause, he demanded the Sequani give him more land to accommodate them. This demand concerned Rome because if the Sequani conceded, Ariovistus would be able to take all of their land and attack the rest of Gaul.

Following Caesar’s victory over the Helvetii, most of the Gallic tribes congratulated him and sought to meet in a general assembly. 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. Diviciacus demanded that Caesar defeat Ariovistus and remove the threat of a Germanic invasion otherwise they would have to seek refuge in a new land. 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.

The senate had declared Ariovistus a "king and friend of the Roman people" in 59 BC, so Caesar could not easily declare war on the Suebi tribe. Caesar said he could not ignore the pain the Aedui had suffered and delivered an ultimatum to Ariovistus demanding that no Germanic tribesman cross the Rhine, the return of Aedui hostages and the protection of the Aedui and other friends of Rome. Although Ariovistus assured Caesar that the Aedui hostages would be safe as long as they continued their yearly tribute, he took the position that he and the Romans were both conquerors and that Rome had no jurisdiction over his actions. With the attack of the Harudes 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.

Prior to the battle, Caesar and Ariovistus held a parley. Ariovistus' cavalry cast stones and weapons at the Roman cavalry. Caesar broke off negotiations and instructed his men not to retaliate to prevent the Suebi from claiming they were induced into a trap by their accepting an opportunity to talk.

The next morning Caesar assembled his allied troops in front of the second camp and advanced his legions in triplex acies (three lines of troops) 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 battle that ensued due in large part to the charge made by Publius 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.

The Battle of Vosges is the third major battle of the Gallic Wars. Germanic tribes crossed the Rhine, seeking a home in Gaul.

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.

After the Belgae gave up on their siege of the town of Bibrax, belonging to the Remi tribe, they encamped their army within two Roman miles of Caesar's camp. Although he was reluctant to give battle at first, some minor cavalry skirmishes between the camps gave Caesar the impression that his men were not inferior to the Belgae, and thus decided on a pitched battle.

As Caesar's forces were outnumbered and thus at risk of being out-flanked, he had his army build two trenches, each 400 paces long, one on each side of the plain before the Roman camp. At the end of these trenches, Caesar had small forts built in which he placed his artillery. Then, leaving two legions as a reserve in the camp, he drew up his remaining six in battle order, and the enemy did the same. The crux of the battle lay in the small marsh that was situated between the two armies, and both forces anxiously anticipated the other's crossing of this obstacle, as it was sure to disorder the forces that did so. Cavalry skirmishes began the battle, although neither force crossed the marsh. Caesar claims his forces came out favourably in these initial actions, and so led his forces back to his camp.

After Caesar's manoeuver the Belgic forces circumvented the camp and endeavoured to approach it from behind. The rear of the camp was bordered by the river Axona (today called the River Aisne), and the Belgae sought to attack the camp via a single fording spot in the river. Caesar claims their intention was to lead a part of their force over the bridge, and either take the camp by storm, or cut the Romans off from the lands on the opposite side of the river. This tactic would both deprive the Romans of land for foraging, and prevent them from coming to the aid of the Remi tribe whose lands the Belgae had the intention of pillaging (as mentioned in the Prelude, above). To counter this manoeuver, Caesar sent all his light infantry and cavalry to manage the difficult terrain (as it would have been more difficult for the heavy infantry to do so). 

Dismayed by the courageous attack by Caesar's men, and by their consequent inability to either take the camp by storm or blockade the Romans from crossing the river, the Belgic forces withdrew to their camp. Then, calling a council of war, they immediately resigned to returning to their home territories, where they might better be able to engage Caesar's invading army.

So rushed and unorganized was the Belgic departure from their camp, that it seemed very much like a panicked retreat to the Roman forces. However, as Caesar was as yet unaware of their reason for departing, he decided not to immediately pursue the forces, for fear of an ambush. The following day, after learning from his scouts of the fully-fledged retreat of the Belgic forces, Caesar sent three legions and all his cavalry to attack the rear of the Belgic marching column. In his account of this action, Caesar claims that these Roman forces killed as many men as the daylight allowed, without any risk to themselves (as the Belgic forces were taken by surprise and breaking rank, sought safety in flight).

After the Battle of Axona, Caesar continued his advance and tribes surrendered one by one. However, four tribes, the Nervii, the Atrebates, the Aduatuci, and the Viromandui refused to submit. The Ambiani told Caesar that the Nervii were the most hostile of the Belgae to Roman rule. A fierce and brave tribe, they did not allow the import of luxury items as they believed these had a corrupting effect and probably feared Roman influence. They had no intention of entering peace negotiations with the Romans. Caesar would move on them next.

The Battle of the Sabis was fought in 57 BC near modern Saulzoir in Northern France, between Caesar's legions and an association of Belgae tribes, principally the Nervii. Julius Caesar, commanding the Roman forces, was surprised and nearly defeated. According to Caesar's report, a combination of determined defence, skilled generalship, and the timely arrival of reinforcements allowed the Romans to turn a strategic defeat into a tactical victory. Few primary sources describe the battle in detail, with most information coming from Caesar's own report on the battle from his book, Commentarii de Bello Gallico. Little is therefore known about the Nervii perspective on the battle. The Veneti, the Unelli, the Osismii, the Curiosolitae, the Sesuvii, the Aulerci and the Rhedones were all brought under Roman control following the battle.

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.

At last, the Roman fleet sailed, and encountered the Venetic fleet off the coast of Brittany in the Gulf of Morbihan. 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.

The Veneti, now without a navy, had been bested. They surrendered, and Caesar made an example of the tribal elders by executing them. He sold the rest of the Veneti into slavery. Caesar now turned his attention to the Morini and Menapii along the coast.

During the Venetic campaign, Caesar's subordinates had been busy pacifying Normandy and Aquitania. A coalition of Lexovii, Coriosolites, and Venelli charged Sabinus while he was entrenched atop a hill. This was a poor tactical move by the tribes. By the time they had reached the top, they were exhausted, and Sabinus defeated them with ease. The tribes consequently surrendered, yielding up all of Normandy to the Romans. Crassus did not have such an easy time in facing the Aquitania. With only one legion and some cavalry, he was outnumbered. He raised additional forces from Provence and marched south to what is now the border of modern Spain and France. Along the way, he fought off the Sotiates, who attacked while the Romans were marching. Defeating the Vocates and Tarusates proved a tougher task. Having allied with the rebel Roman general Quintus Sertorius during his uprising in 70 BC, these tribes were well versed in Roman combat, and had learned guerilla tactics from the war. They avoided frontal battle and harassed supply lines and the marching Romans. Crassus realized he would have to force battle and located the Gallic encampment of some 50,000. However, they had only fortified the front of the camp, and Crassus simply circled it and attacked the rear. Taken by surprise, the Gauls attempted to flee. However, Crassus' cavalry pursued them. According to Crassus, only 12,000 survived the overwhelming Roman victory. The tribes surrendered, and Rome now controlled most of southwest Gaul.

In 56 BC, the Sotiates were led by their chief Adiatuanos in the defence of their oppidum against the Roman officer P. Licinius Crassus. After a failed sortie attempt with 600 of his soldurii, Adiatuanos had to capitulate to the Romans.

Cassius then marched his army into the borders of the Sotiates. Hearing of his approach, the Sotiates collected a large force, with cavalry, in which lay their chief strength, and attacked our column on the march. First of all they engaged in a cavalry combat; then, when their cavalry were beaten, and ours pursued, they suddenly unmasked their infantry force, which they had posted in ambush in a valley. The infantry attacked our scattered horsemen and renewed the fight.

The battle was long and fierce. The Sotiates, with the confidence of previous victories, felt that upon their own courage depended the safety of all Aquitania: the Romans were eager to have it seen what they could accomplish under a young leader without the commander-in-chief and the rest of the legions. At last, however, after heavy casualties the enemy fled from the field. A large number of them were slain; and then Crassus turned direct from his march and began to attack the stronghold of the Sotiates. When they offered a brave resistance he brought up mantlets and towers.

The enemy at one time attempted a sortie, at another pushed mines as far as the ramp and the mantlets—and in mining the Aquitani are by far the most experienced of men, because in many localities among them there are copper-mines and diggings. When they perceived that by reason of the efficiency of our troops no advantage was to be gained by these expedients, they sent deputies to Crassus and besought him to accept their surrender.

Their request was granted, and they proceeded to deliver up their arms as ordered. Then, while the attention of all our troops was engaged upon that business, Adiatunnus, the commander-in-chief, took action from another quarter of the town with six hundred devotees, whom they call vassals. The rule of these men is that in life they enjoy all benefits with the comrades to whose friendship they have committed themselves, while if any violent fate befalls their fellows, they either endure the same misfortune along with them or take their own lives; and no one yet in the memory of man has been found to refuse death, after the slaughter of the comrade to whose friendship he had devoted himself. With these men Adiatunnus tried to make a sortie; but a shout was raised on that side of the entrenchment, the troops ran to arms, and a sharp engagement was fought there. Adiatunnus was driven back into the town; but, for all that, he begged and obtained from Crassus the same terms of surrender as at first.

— Julius Caesar. Bellum Gallicum. 3, 20–22. Loeb Classical Library. Translated by H. J. Edwards, 1917.

Defeating the Vocates and Tarusates proved a tougher task. Having allied with the rebel Roman general Quintus Sertorius during his uprising in 70 BC, these tribes were well versed in Roman combat, and had learned guerilla tactics from the war. They avoided frontal battle and harassed supply lines and the marching Romans. Crassus realized he would have to force battle and located the Gallic encampment of some 50,000. However, they had only fortified the front of the camp, and Crassus simply circled it and attacked the rear. Taken by surprise, the Gauls attempted to flee. However, Crassus' cavalry pursued them. According to Crassus, only 12,000 survived the overwhelming Roman victory. The tribes surrendered, and Rome now controlled most of southwest Gaul.

A need for prestige more than tactical concerns likely determined Caesar's campaigns in 55 BC, due to Pompey and Crassus' consulship. On the one hand, they were Caesar's political allies, and Crassus's son had fought under him the year before. But they were also his rivals, and had formidable reputations (Pompey was a great general, and Crassus was fabulously wealthy). Since the consuls could easily sway and buy public opinion, Caesar needed to stay in the public eye. His solution was to cross two water bodies no Roman army had attempted before: the Rhine and the English Channel. Crossing the Rhine was a consequence of Germanic/Celtic unrest. The Suebi had recently forced the Celtic Usipetes and Tencteri from their lands, who resultingly had crossed the Rhine in search of a new home. Caesar, however, had denied their earlier request to settle in Gaul, and the issue turned to war. The Celtic tribes sent out a cavalry force of 800 against a Roman auxiliary force of 5,000 made up of Gauls, and won a surprising victory. Caesar retaliated by attacking the defenseless Celtic camp, and slaughtering the men, women, and children. Caesar claims he killed 430,000 people in the camp. Modern historians find this number impossibly high (see historiography below), but it is apparent that Caesar killed a great many Celts. So cruel were his actions, his enemies in the Senate wished to prosecute him for war crimes once his tenure as governor was up and he was no longer immune from prosecution. After the massacre, Caesar led the first Roman army across the Rhine in a lightning campaign that lasted just 18 days.

Historian Kate Gilliver considers all of Caesar's actions in 55 BC to be a "publicity stunt" and suggests that the basis for continuing the Celtic/Germanic campaign was a desire to gain prestige. This also explains the campaign's brief time span. Caesar wanted to impress the Romans and scare the Germanic tribesmen, and he did this by crossing the Rhine in style. Instead of using boats or pontoons as he had in earlier campaigns, he built a timber bridge in a mere ten days. He walked across, raided the Suebic countryside, and retreated across the bridge before the Seubic army could mobilize. He then burned the bridge and turned his attentions to another feat no Roman army had accomplished before—landing in Britain. The nominal reason to attack Britain was the Britonic tribes had been assisting the Gauls, but like most of Caesar's casus belli it was just an excuse to gain stature in the eyes of the Roman people.

In late summer, 55 BC, even though it was late in the campaigning season, Caesar decided to make an expedition to Britain. He summoned merchants who traded with the island, but they were unable or unwilling to give him any useful information about the inhabitants and their military tactics, or about harbours he could use, presumably not wanting to lose their monopoly on cross-channel trade. He sent a tribune, Gaius Volusenus, to scout the coast in a single warship. He probably examined the Kent coast between Hythe and Sandwich, but was unable to land, since he "did not dare leave his ship and entrust himself to the barbarians", and after five days returned to give Caesar what intelligence he had managed to gather.

By then, ambassadors from some of the British states, warned by merchants of the impending invasion, had arrived promising their submission. Caesar sent them back, along with his ally Commius, king of the Belgae Atrebates, to use their influence to win over as many other states as possible.

He gathered a fleet consisting of eighty transport ships, sufficient to carry two legions (Legio VII and Legio X), and an unknown number of warships under a quaestor, at an unnamed port in the territory of the Morini, almost certainly Portus Itius (Boulogne). Another eighteen transports of cavalry were to sail from a different port, probably Ambleteuse. These ships may have been triremes or biremes, or may have been adapted from Venetic designs Caesar had seen previously, or may even have been requisitioned from the Veneti and other coastal tribes. Clearly in a hurry, Caesar himself left a garrison at the port and set out "at the third watch" – well after midnight – on 23 August with the legions, leaving the cavalry to march to their ships, embark, and join him as soon as possible. In light of later events, this was either a tactical mistake or (along with the fact that the legions came over without baggage or heavy siege gear) confirms the invasion was not intended for complete conquest.

Caesar's first trip into Britain was less an invasion than an expedition. He took only two legions; his cavalry auxiliaries were unable to make the crossing despite several attempts. Caesar crossed late in the season, and in great haste, leaving well after midnight on 23 August. Initially, he planned to land somewhere in Kent, but the Britons were waiting for him. He moved up the coast and landed—modern archeological finds suggest at Pegwell Bay—but the Britons had kept pace and fielded an impressive force, including cavalry and chariots. The legions were hesitant to go ashore. Eventually, the X legion's standard bearer jumped into the sea and waded to shore. To have the legion's standard fall in combat was the greatest humiliation, and the men disembarked to protect the standard bearer. After some delay, a battle line was finally formed, and the Britons withdrew. Because the Roman cavalry had not made the crossing, Caesar could not chase down the Britons. The Romans' luck did not improve, and a Roman foraging party was ambushed. The Britons took this as a sign of Roman weakness and amassed a large force to assault them. A short battle ensued, though Caesar provides no details beyond indicating the Romans prevailed. Again, the lack of cavalry to chase down the fleeing Britons prevented a decisive victory. The campaigning season was now nearly over, and the legions were in no condition to winter on the coast of Kent. Caesar withdrew back across the Channel.

Gilliver notes that Caesar once again narrowly escaped disaster. Taking an understrength army with few provisions to a far-off land was a poor tactical decision, which easily could have led to Caesar's defeat – yet he survived. While he had achieved no significant gains in Britain, he had accomplished a monumental feat simply by landing there. It was a fabulous propaganda victory as well, which was chronicled in Caesar's ongoing Commentarii de Bello Gallico. The writings in the Commentarii fed Rome a steady update of Caesar's exploits (with his own personal spin on events). Caesar's goal of prestige and publicity succeeded enormously: upon his return to Rome, he was hailed as a hero and given an unprecedented 20-day thanksgiving. He now began planning for a proper invasion of Britain.

Caesar's approach towards Britain in 54 BC was far more comprehensive and successful than his initial expedition. New ships had been built over the winter, and Caesar now took five legions and 2,000 cavalry. He left the rest of his army in Gaul to keep order. Gilliver notes that Caesar took with him a good number of Gallic chiefs whom he considered untrustworthy so he could keep an eye on them, a further sign that he had not comprehensively conquered Gaul.

Determined not to make the same mistakes as the previous year, Caesar gathered a larger force than on his previous expedition with five legions as opposed to two, plus two thousand cavalry, carried in ships which he designed, with experience of Venetic shipbuilding technology so as to be more suitable for a beach landing than those used in 55 BC, being broader and lower for easier beaching. This time he named Portus Itius as the departure point.

Titus Labienus was left at Portus Itius to oversee regular food transports from there to the British beachhead. The military ships were joined by a flotilla of trading ships captained by Romans and provincials from across the empire, and local Gauls, hoping to cash in on the trading opportunities. It seems more likely that the figure Caesar quotes for the fleet (800 ships) include these traders and the troop-transports, rather than the troop-transports alone.

Caesar landed without resistance and immediately went to find the Britonic army. The Britons used guerilla tactics to avoid a direct confrontation. This allowed them to gather a formidable army under Cassivellaunus, king of the Catuvellauni. The Britonic army had superior mobility due to its cavalry and chariots, which easily allowed them to evade and harass the Romans. The Britons attacked a foraging party, hoping to pick off the isolated group, but the party fought back fiercely and thoroughly defeated the Britons. They mostly gave up resistance at this point, and a great many tribes surrendered and offered tribute.

Upon landing, Caesar left Quintus Atrius in charge of the beach-head and made an immediate night march 12 mi (19 km) inland, where he encountered the British forces at a river crossing, probably somewhere on the River Stour. The Britons attacked but were repulsed, and attempted to regroup at a fortified place in the forests, possibly the hillfort at Bigbury Wood, Kent, but were again defeated and scattered. As it was late in the day and Caesar was unsure of the territory, he called off the pursuit and made camp.

However, the next morning, as he prepared to advance further, Caesar received word from Atrius that, once again, his ships at anchor had been dashed against each other in a storm and suffered considerable damage. About forty, he says, were lost. The Romans were unused to Atlantic and Channel tides and storms, but nevertheless, considering the damage he had sustained the previous year, this was poor planning on Caesar's part. However, Caesar may have exaggerated the number of ships wrecked to magnify his own achievement in rescuing the situation. He returned to the coast, recalling the legions that had gone ahead, and immediately set about repairing his fleet. His men worked day and night for approximately ten days, beaching and repairing the ships, and building a fortified camp around them. Word was sent to Labienus to send more ships.

Caesar was on the coast on 1 September, from where he wrote a letter to Cicero. News must have reached Caesar at this point of the death of his daughter Julia, as Cicero refrained from replying "on account of his mourning".

The Britons had appointed Cassivellaunus, a warlord from north of the Thames, to lead their combined forces. Cassivellaunus realised he could not defeat Caesar in a pitched battle. Disbanding the majority of his force and relying on the mobility of his 4,000 chariots and superior knowledge of the terrain, he used guerrilla tactics to slow the Roman advance. By the time Caesar reached the Thames, the one fordable place available to him had been fortified with sharpened stakes, both on the shore and under the water, and the far bank was defended.

The Trinovantes, whom Caesar describes as the most powerful tribe in the region, and who had recently suffered at Cassivellaunus' hands, sent ambassadors, promising him aid and provisions. Mandubracius, who had accompanied Caesar, was restored as their king, and the Trinovantes provided grain and hostages. Five further tribes, the Cenimagni, Segontiaci, Ancalites, Bibroci and Cassi, surrendered to Caesar, and revealed to him the location of Cassivellaunus' stronghold, possibly the hill fort at Wheathampstead, which he proceeded to put under siege.

Cassivellaunus sent word to his allies in Kent, Cingetorix, Carvilius, Taximagulus and Segovax, described as the "four kings of Cantium", to stage a diversionary attack on the Roman beach-head to draw Caesar off, but this attack failed, and Cassivellaunus sent ambassadors to negotiate a surrender. Caesar was eager to return to Gaul for the winter due to growing unrest there, and an agreement was mediated by Commius. Cassivellaunus gave hostages, agreed an annual tribute, and undertook not to make war against Mandubracius or the Trinovantes. Caesar wrote to Cicero on 26 September, confirming the result of the campaign, with hostages but no booty taken, and that his army was about to return to Gaul. He then left, leaving not a single Roman soldier in Britain to enforce his settlement. Whether the tribute was ever paid is unknown.

Discontent among the subjugated Gauls prompted a major uprising amongst the Belgae against Julius Caesar in the winter of 54–53 BC, when the Eburones of north-eastern Gaul rose in rebellion under their leader Ambiorix.

The Eburones, who until Caesar's destruction of the Atuatuci had been vassals of that Belgic tribe, were ruled by Ambiorix and Catuvolcus. In 54 BC there was a poor harvest, and Caesar, whose practice was to commandeer a part of the food supply from the local tribes, was forced to split his legions up among a larger number of tribes. To the Eburones he sent Quintus Titurius Sabinus and Lucius Aurunculeius Cotta with the command of a recently levied 14th Legion from north of the Po and a detachment of five cohorts, a total strength of 9,000 men. Ambiorix and his tribesmen attacked and killed several Roman soldiers who were foraging for wood in the nearby vicinity.

One morning, the Romans marched out of their fort. The enemy heard the hubbub in the Fort and prepared an ambush. When dawn broke, the Romans, in marching order (long columns of soldiers with each unit following the other), more heavily burdened than usual left the Fort. When the greater part of the column had entered a ravine, the Gauls assaulted them from either side and sought to harry the rearguard and prevent the vanguard from leaving the ravine.

Due to the length of the column, the commanders could not issue orders efficiently so they passed word along the line to the units to form into a square. The troops fought bravely though with fear and in clashes were successful. Thus, Ambiorix ordered his men to discharge their spears into the troops, to fall back if attacked by a group of Romans and chase back the Romans when they tried to fall into rank.

Sabinus sent word to Ambiorix to treat for surrender, a proposal which was acceded to. Cotta refused to come to terms and remained steadfast in his refusal to surrender, while Sabinus followed through with his plan to surrender. However, Ambiorix, after promising Sabinus his life and the safety of his troops, distracted him with a long speech, all the while slowly surrounding him and his men and slaughtering them. The Gauls then charged down en masse onto the waiting Romans where they killed Cotta, still fighting, and the great majority of the troops. The remainder fell back to the fort where, despairing of help, they killed each other. Only a few men slipped away to inform Titus Labienus of the disaster. Overall, one legion and 5 cohorts, around 7500 Romans, were killed in the battle.

The rest of 53 BC was occupied with a punitive campaign against the Eburones and their allies, who were said to have been all but exterminated by the Romans.

The winter uprising of 54 BC had been a fiasco for the Romans. One legion had been lost entirely, and another almost destroyed. The revolts had shown the Romans were not truly in command of Gaul. Caesar set out on a campaign to subjugate the Gauls completely and forestall future resistance. Down to seven legions, he needed more men. Two more legions were recruited, and one was borrowed from Pompey. The Romans now had 40,000–50,000 men. Caesar began the brutal campaign early, before the weather had warmed. He focused on a non-traditional campaign, demoralizing populations and attacking civilians. He assaulted the Nervii and focused his energy on raiding, burning villages, stealing livestock, and taking prisoners. This strategy worked, and the Nervii promptly surrendered. The legions returned to their wintering spots until the campaign season started fully. Once the weather warmed, Caesar pulled a surprise attack on the Senones. Having had no time to prepare for a siege or even withdraw to their oppidum, the Senones also surrendered. Attention turned to the Menapii, where Caesar followed the same strategy of raiding he had used on the Nervii. It worked just as well on the Menapii, who surrendered quickly.

Caesar's legions had been split up to put down more tribes, and his lieutenant Titus Labienus had with him 25 cohorts (about 12,000 men) and a good deal of cavalry in the lands of the Treveri (led by Indutiomarus). The Germanic tribes had promised aid to the Treveri, and Labienus realized that his relatively small force would be at a serious disadvantage. Thus, he sought to bait the Treveri into an attack on his terms. He did so by feinting a withdrawal, and the Treveri took the bait. However, Labienus had made sure to feint up a hill, requiring the Treveri to run up it, so by the time they reached the top, they were exhausted. Labienus dropped the pretense of withdrawing and gave battle defeating the Treveri in minutes; the tribe surrendered shortly after. In the rest of Belgium, three legions raided the remaining tribes and forced widespread surrender, including the Eburones under Ambiorix.

Caesar now sought to punish the Germanic tribes for daring to help the Gauls. He took his legions over the Rhine once more by building a bridge. But again, Caesar's supplies failed him, forcing him to withdraw to avoid engaging with the still mighty Suebi while short on supplies. Regardless, Caesar had exacted widespread surrender through a vicious retaliatory campaign that focused on destruction over battle. Northern Gaul was essentially flattened. At the end of the year, six legions were wintered, two each on the lands of the Senones, the Treveri, and the Lingones. Caesar aimed to prevent a repeat of the previous disastrous winter, but given the brutality of Caesar's actions that year, an uprising could not be stopped by garrisons alone.

Gallic existential concerns came to a head in 52 BC and caused the widespread revolt the Romans had long feared. The campaigns of 53 BC had been particularly harsh, and the Gauls feared for their prosperity. Previously, they had not been united, which had made them easy to conquer. But this changed in 53 BC, when Caesar announced that Gaul was now being treated as a Roman province, subject to Roman laws and religion. This was a subject of immense concern for the Gauls, who feared the Romans would destroy the Gallic holy land, which the Carnutes watched over. Each year the druids met there to mediate between the tribes on the lands considered the center of Gaul. A threat to their sacred lands was an issue that finally united the Gauls. Over the winter the charismatic king of the Arverni tribe, Vercingetorix, assembled an unprecedented grand coalition of Gauls.

Caesar was still in Rome when news of the revolt reached him. He rushed to Gaul in an attempt to prevent the revolt from spreading, heading first to Provence to see to its defense, and then to Agedincum to counter the Gallic forces. Caesar took a winding route to the Gallic army to capture several oppidium for food. Vercingetorix was forced to withdraw from his siege of the Boii capital of Gorgobina (the Boii had been allied to Rome since their defeat at Roman hands in 58 BC). However, it was still winter, and he realized the reason Caesar had detoured was that the Romans were low on supplies. Thus, Vercingetorix set out a strategy to starve the Romans. He avoided attacking them outright and raided foraging parties and supply trains instead. Vercingetorix abandoned a great many oppidum, seeking only to defend the strongest, and to ensure the others and their supplies could not fall into Roman hands. Once again, a lack of supplies forced Caesar's hand, and he sieged the oppidum of Avaricum where Vercingetorix had sought refuge.

Originally, Vercingetorix had been opposed to defending Avaricum, but the Bituriges Cubi had persuaded him otherwise. The Gallic army was camped outside the settlement. Even while defending, Vercingetorix wished to abandon the siege and outrun the Romans. But the warriors of Avaricum were unwilling to leave it. Upon his arrival, Caesar promptly began construction of a defensive fortification. The Gauls continuously harassed the Romans and their foraging parties while they built their camp and attempted to burn it down. But not even the fierce winter weather could stop the Romans, and they built a very sturdy camp in just 25 days. The Romans built siege engines, and Caesar waited for an opportunity to attack the heavily fortified oppidum. He chose to attack during a rainstorm when the sentries were distracted. Siege towers were used to assault the fort, and ballista artillery battered the walls. Eventually, the artillery broke a hole in a wall, and the Gauls could not stop the Romans from taking the settlement. The Romans then looted and pillaged Avaricum; Caesar took no prisoners and claims the Romans slew 40,000. That the Gallic coalition did not fall apart after this defeat is a testament to the leadership of Vercingetorix. Even after losing Avaricum, the Aedui were willing to revolt and join the coalition. This was yet another setback to Caesar's supply lines, as he could no longer get supplies through the Aedui (though the taking of Avaricum had supplied the army for the moment).

Vercingetorix now withdrew to Gergovia, the capital of his own tribe, which he was eager to defend. Caesar arrived as the weather warmed, and fodder finally became available, which somewhat eased supply issues. As usual, Caesar promptly set about building a fortification for the Romans. He captured territory closer to the oppidum.

The loyalty of the Aedui to Rome was not entirely stable. Caesar suggests in his writing that Aeudui leaders were both bribed gold and sent misinformation by emissaries of Vercingetorix. Caesar had agreed with the Aedui that 10,000 men would protect his line of supplies. Vercingetorix convinced the chief, Convictolitavis, who had been made chief of the tribe by Caesar, to order the same men to join him upon their arrival at the oppidum. They attacked the Romans who were accompanying their supply train, leaving Caesar in an embarrassing position. His rations threatened, Caesar took four legions from the siege, surrounded the Aedui army, and defeated it. The pro-Roman faction retook control of the Aedui leadership, and Caesar returned to Gergovia with 10,000 pro-Roman Aedui horsemen. The two legions that he had left to continue the siege had been hard-pressed to keep Vercingetorix's much larger force at bay.

Caesar realized that his siege would fail unless he could get Vercingetorix off the high ground. He used one legion as a decoy while the rest moved onto better ground, capturing three Gallic camps in the process. He then ordered a general retreat to lure Vercingetorix off the high ground. However, the order was not heard by most of Caesar's force. Instead, spurred on by the ease with which they captured the camps, they pressed on toward the town and mounted a direct assault on it, exhausting themselves.

Caesar's work records 46 centurions and 700 legionaries as losses. Modern historians are skeptical; the depiction of the battle as a rout, and one where there were 20,000-40,000 allied Roman soldiers deployed, leads to suspicion that Caesar was downplaying the casualty figures, even if his figures were excluding losses among allied auxiliaries. Given his losses, Caesar ordered a retreat. In the wake of the battle, Caesar lifted his siege and retreated from the Arverni lands northeastwards in the direction of Aedui territory. Vercingetorix pursued Caesar's army, intent on destroying it. Meanwhile, Labienus had finished his campaign in the north and marched back to Agendicum, Caesar's base in the centre of Gaul. After linking up with Labienus's corps, Caesar marched his united army from Agendicum to confront Vercingetorix's victorious army. The two armies met at the Vingeanne, Caesar won the subsequent battle. 

Caesar sent Labienus to campaign against the peoples of the Seine, whilst Caesar himself marched on Gergovia. He captured the oppidum of Metlosedum (possibly present-day Melun), and crossed the Seine to attack the Gallic coalition near Lutetia. Threatened by the Bellovaci (a powerful Belgae tribe), he decided to re-cross the Seine to rejoin Caesar's force at Agedincum (Sens). Feinting a general retreat, Labienus in fact crossed the river. The Gauls of the Seine coalition tried to block his path to Caesar and battle was joined.

After the two sides engaged the Seventh legion, placed on the right wing, started to push back the Gallic left. On the Roman left the Twelfth legion's pilum volleys broke up the Gauls first charge, but they resisted the Romans advance, encouraged by their old chieftain Camulogenus. The turning point came when the military tribunes of the Seventh legion led their legionaries against the enemy rear.

After the two sides engaged the Seventh legion, placed on the right wing, started to push back the Gallic left. On the Roman left the Twelfth legion's pilum volleys broke up the Gauls first charge, but they resisted the Romans advance, encouraged by their old chieftain Camulogenus. The turning point came when the military tribunes of the Seventh legion led their legionaries against the enemy rear. The Gauls sent in their reserves, taking a nearby hill, but were unable to reverse the course of the battle and took flight. Their losses increased when the Roman cavalry was sent to pursue them. Labienus's force thus advanced back to Agedincum, recaptured their baggage train along the way.

The Gauls tried to prevent Labienus from returning to Agedincum by blocking him at the Sequana river. Labienus used five cohorts to lure the Gauls away while he himself crossed the Sequana River with three legions. When the Gauls found out there were two Roman armies in the area they split up and pursued both. The main body met Labienus who pinned them down with one legion while surrounding them with the rest. He then annihilated their reinforcements with his cavalry. After linking up with the five cohorts he had used as a diversion, Labienus marched his army back to Agendicum where he met up with Caesar returning from his defeat at Gergovia. 

In July 52 BC the Roman general Julius Caesar fought an important battle of the Gallic Wars against a coalition of Gauls led by Vercingetorix. Caesar responded to an attack against Gallia Narbonensis by leading his forces east through Lingones territory towards Sequani territory, probably marching down the Vingeanne valley. He had recently recruited (or hired) German cavalry, and they would prove decisive.

The Gallic army held a very strong position guarded by high slopes, easy to defend. It was protected by the Vingeanne on the right, and the Badin, a small tributary of the Vingeanne, on its front. In the space between these two streams and the road from Dijon to Langres was an area 5 kilometres (3.1 mi) across, slightly uneven in some parts, almost flat everywhere else, mainly between the Vingeanne and the hillock of Montsuageon. Near the road, and to the west, rise hills which dominated the ground, as well as the whole country, up to the Badin and the Vingeanne.

The Gauls thought the Romans were retreating towards Italy and decided to attack. One group of Gallic cavalry blocked the Roman advance while two groups of cavalry harried the Roman's flanks. After hard fighting, the German cavalry broke the Gallic cavalry on the right and chased them back to the main Gallic infantry force. The remaining Gallic cavalry fled, and Vercingetorix was forced to retreat to Alesia, where he was besieged by the Romans.

The Battle of Alesia or Siege of Alesia was a military engagement in the Gallic Wars around the Gallic oppidum (fortified settlement) of Alesia, a major centre of the Mandubii tribe. It was the last major engagement between Gauls and Romans, and is considered one of Caesar's greatest military achievements and a classic example of siege warfare and investment; the Roman army built dual lines of fortifications—an inner wall to keep the besieged Gauls in, and an outer wall to keep the Gallic relief force out. The Battle of Alesia marked the end of Gallic independence in modern day territory of France and Belgium.

With the revolt crushed, Caesar set his legions to winter across the lands of the defeated tribes to prevent further rebellion. Troops were also sent to the Remi, who had been steadfast allies to the Romans throughout the campaign. But resistance was not entirely over: southwest Gaul had not yet been pacified. Alesia proved to be the end of generalized and organized resistance against Caesar's invasion of Gaul and effectively marked the end of the Gallic Wars. In the next year (50 BC) there were mopping-up operations. During the Roman civil wars Gallia was essentially left on its own. 

The spring of 51 BC saw the legions campaign among the Belgic tribes to snuff out any thoughts of an uprising, and the Romans achieved peace. But two chiefs in southwest Gaul, Drappes and Lucterius, remained openly hostile to the Romans and had fortified the formidable Cadurci oppidum of Uxellodunum. Gaius Caninius Rebilus surrounded the oppidum and set the siege of Uxellodunum, focusing on building a series of camps, a circumvallation, and disrupting Gallic access to water. A series of tunnels (of which archeological evidence has been found) were dug to the spring that fed the city. The Gauls attempted to burn down the Roman siege works, but to no avail. Eventually, the Roman tunnels reached the spring and diverted the water supply. Not realizing the Roman action, the Gauls believed the spring going dry was a sign from the Gods and surrendered. Caesar chose not to slaughter the defenders, and instead just cut off their hands as an example.

Lucterius, the chief of the Carduci, and Drapes, chief of the Senones, had retired to the hill fort of Uxellodunum to remain in the relative safety of the fortifications until the governorship of Gaius Julius Caesar ended in Gaul. The group had apparently planned to then begin a new rebellion against their Roman conquerors.

While these actions had been ongoing, Gaius Julius Caesar was in the territory of the Belgae in Gaul. There he was informed by courier of the revolt of the Carduci and Senones. Determined to ensure that there would be no more rebellions in Gaul after the expiration of his tenure as governor, Caesar set out immediately for Uxellodunum with his cavalry, leaving behind his legions, even though his two legates had the situation under control. Indeed, Caesar made his way so quickly to Uxellodunum that he surprised his two legates.

Caesar decided that the city could not be carried by force. Caesar noticed the difficulty the Gauls had collecting the water, having to come down a very steep slope to reach the riverbank. Exploiting this potential flaw in the defences, Caesar stationed archers and ballista near the river to cover any attempt to gather water from this main source. More troublesome for Caesar however, a secondary water source flowed down from the mountain directly underneath the walls of the fort. It seemed to be almost impossible to block access to this second source. The terrain was extremely rugged and it would not have been feasible to take the ground by force. Before long, Caesar was informed of the location of the source of the spring. With this knowledge, he ordered his engineers to build a ramp of earth and rock that could support a ten-story siege tower, which he used to bombard the spring source. Concurrently, he had another group of engineers build a tunnel system that finished at the source of the same spring. Shortly thereafter, the sappers tunnelled through to the water source and finished the job of cutting the Gauls off from their water sources, forcing the Gauls to surrender their unfavourable position.

Caesar accepted the Gallic surrender. However he decided to ensure that this would mark the last Gallic rebellion by setting a severe example. He decided against executing or selling the survivors into slavery, as had been customary in contemporary battles. Instead, he had the hands of all the surviving men of military age cut off, but left them alive. He then dispersed the vanquished Gauls throughout the province for all to see that they would never again be able to take up arms against him or the Roman Republic.

After dealing with the Gaulish rebels, Caesar took two of the legions and marched with a view to spend the summer in Aquitania which he had previously not visited. He briefly passed through the city of Narbo Martius in the Roman province of Gallia Narbonensis and marched through Nementocenna. Deeming Gaul sufficiently pacified, as no further rebellions arose, Caesar took the 13th Legion and marched to Italy, where he proceeded to cross the Rubicon and start the Great Roman Civil War on 17 December 50 BC.

In the span of eight years, Caesar had conquered all of Gaul and part of Britain. He had become fabulously wealthy and achieved a legendary reputation. The Gallic Wars provided enough gravitas to Caesar that subsequently he was able to wage a civil war and declare himself dictator, in a series of events that would eventually lead to the end of the Roman Republic.

The Gallic Wars lack a clear end date. Legions continued to be active in Gaul through 50 BC, when Aulus Hirtius took over the writing of Caesar's reports on the war. The campaigns may well have continued into Germanic lands, if not for the impending Roman civil war. The legions in Gaul were eventually pulled out in 50 BC as the civil war drew near, for Caesar would need them to defeat his enemies in Rome. The Gauls had not been entirely subjugated and were not yet a formal part of the empire. But that task was not Caesar's, and he left that to his successors. Gaul would not be made formally into Roman provinces until the reign of Augustus in 27 BC. Several rebellions happened subsequently, and Roman troops were kept stationed throughout Gaul. Historian Gilliver thinks there could have been unrest in the region as late as 70 AD, but not to the level of Vercingetorix's revolt.

The conquest of Gaul marked the beginning of almost five centuries of Roman rule, which would have profound cultural and historical impacts. Roman rule brought with it Latin, the language of the Romans. This would evolve into Old French, giving the modern French language its Latin roots. 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.