Gallic Wars The Gallic Wars were a series of military campaign s waged by the Roman proconsul Julius Caesar against several Gallic tribes . Rome ' s war against the Gallic tribes lasted from 58 BC to 50 BC and culminated in the decisive Battle of Alesia in 52 BC , in which a complete Roman victory resulted in the expansion of the Roman Republic over the whole of Gaul ( mainly present day France and Belgium ) . The wars paved the way for Julius Caesar to become the sole ruler of the Roman Republic . Although Caesar portrayed this invasion as being a preemptive and defensive action , most historians agree that the wars were fought primarily to boost Caesar ' s political career and to pay off his massive debts . Still , Gaul was of significant military importance to the Romans , as these had been attacked several times by native tribes both indigenous to Gaul and farther to the north . Conquering Gaul allowed Rome to secure the natural border of the river Rhine . The Gallic Wars are described by Julius Caesar in his book " Commentarii de Bello Gallico " , which is the most important historical source regarding the conflict . Political background . As a result of the financial burdens of his consulship in 59 BC , Caesar incurred significant debt . However , through his membership in the First Triumvirate — the political alliance which comprised Marcus Licinius Crassus , and Pompey , and himself — Caesar had secured the proconsulship of two provinces , Cisalpine Gaul and Illyricum . When the governor of Transalpine Gaul , Metellus Celer , died unexpectedly , this province was also awarded to Caesar . Caesar ' s governorships were extended to a five - year period , a new idea at the time . Caesar had initially four veteran legions under his direct command : 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 personally most ( perhaps even all ) of these legions . Caesar also had the legal authority to levy additional legions and auxiliary units as he saw fit . His ambition was to conquer and plunder some territories to get himself out of debt , and it is likely Gaul was not his initial target . It is likely he was planning a campaign against the kingdom of Dacia located in the Balkans . The countries of Gaul were civilized and wealthy . Most had contact with Roman merchants and some , particularly those that were governed by Republics such as the Aedui and Helvetii , had enjoyed stable political alliances with Rome in the past . The Romans respected and feared the Gallic tribes . Only fifty years before , in 109 BC , Italy had been invaded from the north and saved only after several bloody and costly battles by Gaius Marius . About 62 BC , when a Roman client state , the Arverni , conspired with the Sequani and the Suebi nation east of the Rhine to attack the Aedui , a strong Roman ally , Rome turned a blind eye . The Sequani and Arverni sought Ariovistus ’ aid and defeated the Aedui in 63 BC in the Battle of Magetobriga . The Sequani rewarded Ariovistus with land following his victory . Ariovistus settled the land with 120 , 000 of his people . When 24 , 000 Harudes joined his cause , Ariovistus demanded that the Sequani give him more land to accommodate the Harudes people . This demand ' concerned ' Rome because if the Sequani conceded , Ariovistus would be in a position to take all of the Sequani land and attack the rest of Gaul . They didn ’ t appear to be concerned about a conflict between non - client , client and allied states . By the end of the campaign , the non - client Suebi under the leadership of the belligerent Ariovistus , stood triumphant over both the Aedui and their coconspirators . Fearing another mass migration akin to the devastating Cimbrian War , Rome , now keenly invested in the defense of Gaul , was irrevocably drawn into war . Course . Beginning of the war — campaign against the Helvetii . By 61 BC , the Helvetii were well on their way in the planning and provisioning for a mass migration under the leadership of Orgetorix . The reasons for their migration are mentioned by Caesar in separate passages as either harassment by the Germanic tribes , or not being able to in turn raid for plunder themselves due to their situation in hilly and mountainous territory . During this time the Romans in Gallia Narbonensis were also gaining and taking political advantages and fomenting trade disputes . Via council and parley , the Helvetic chieftain Orgetorix made negotiations with the ambitious Sequani and the Roman dominated Aedui . The Sequani were beginning to resent and regret the abundances of unruly Germanic warbands and their huge encampments of dependents . The Aedui were loath to obey the Roman spur any longer than they must and they were keen to revisit their former days at council . The parley for the trek was successful and Orgetorix was granted passage , and with the trek ratified by council , an army was called up and provisioned for . During this process , Orgetorix had also succeeded in making a personal alliance with the Sequani chieftain Casticus and the Aedui chieftain Dumnorix through marital arrangements and host exchange of family members . For three whole years the Helvetii planned and prepared themselves , and emissaries were sent out to various Gallic tribes assuring safe passages and alliances . Orgetorix ' s Gallic rivals alleged that these political successes and displays of diplomacy were intended to benefit Orgetorix alone and their claims were made more convincing by Roman intrigues and impositions . Again the accord was strained as the Aedui were brought to bay by their " protective " overlords . In 58 BC Orgetorix ' s ambitions were declared a ruse for personal power and this rumor was celebrated among the enemies of the Helvetii , especially those of Roman clientele . This succeeded in causing confusion and feuds among the tribes , based mainly on the merits of Orgetorix versus his vices . There was an effort to seize him at council ; however , he was protected by his retinue and bodyguards . During the preceding seasons he had called up a sizeable force of men - at - arms and vassals said to have numbered 10 , 000 men , this in addition to his armed entourage . Orgetorix was able to escape capture by his rivals and the councils labored at length to resolve the confusions and disputes ; however , Orgetorix was murdered or slain during a dispute within his own encampment . With many conflicts of interest settled , the Helvetii once again returned to their long planned migration to safer pastures among the Santones tribe on the Atlantic seaboard . Caesar dated their departure to the 28 March , and mentions that they burned all their towns and their villages so as to discourage thoughts among undecided client tribes or enemies to occupy their vacated realm . The Helvetii retained and armed their client tribes : the Rauraci , the Tulingi , the Latovici , and the Boii from whom they had hired a contingent of horsemen . There were two available routes for them : the first one was the difficult and dangerous Pas de l ' Ecluse , located between the Jura mountains and the Rhône River . The second , easier one would lead them to the town of Geneva , where the Lake Geneva flows into the Rhone River and where a bridge allowed passage over the river . These lands belonged to the Allobroges , a tribe which had been subdued by Rome , and were under the control of the Roman republic . Meanwhile , Caesar was in Rome , and only a single legion was in Transalpine Gaul , the endangered province . As he was informed of these developments , he immediately hurried to Geneva and ordered a levy of several auxiliary units and the destruction of the bridge . The Helvetii sent an embassy under the new leadership of Nammeius and Verucloetius , to negotiate a peaceful passage , promising to do no harm . Caesar stalled the negotiations while his troops fortified their positions behind the river with a sixteen foot high rampart and a parallel trench lined with ballistas ; his legionaries were backed by mercenary archers and slingers and Caesar had also hired and / or conscripted a contingent of Gallic horseman from the Remi . As the embassy returned , Caesar officially refused their request and warned them that any forceful attempt to cross the river would be opposed . Several attempts were quickly beaten off . The Helvetii turned back and entered negotiations with the Sequani to let them pass in a peaceful manner . Leaving his single legion under the command of his second - in - command Titus Labienus , Caesar hurried to Cisalpine Gaul . Upon arrival , he took command of the three legions which were in Aquileia and enrolled two new legions , the Legio XI and the Legio XII . At the head of these five legions , he went the quickest way through the Alps , crossing territories of several hostile tribes and fighting several skirmishes en route . Meanwhile , the Helvetii had already crossed the territories of the Sequani , and were busy pillaging the lands of the Aedui , Ambarri , and Allobroges . These tribes were unable to oppose them , and as Roman allies asked for Caesar ' s help . Caesar obliged them and surprised the Helvetii as they were crossing the river Arar ( modern Saône River ) . Three quarters of the Helvetii had already crossed , but one quarter , the Tigurine ( a Helvetian clan ) , was still on the east bank . Three legions , under Caesar ' s command , surprised and defeated the Tigurine in the Battle of the Arar . The remaining Tigurini fled to neighboring woods . After the battle , the Romans built a bridge over the Saône to pursue the remaining Helvetii . The Helvetii sent an embassy led by Divico , but the negotiations failed . For a fortnight , the Romans maintained their pursuit until they ran into supply troubles . Caesar in the meantime sent 4 , 000 Roman and allied Aedui cavalry to track the Helvetii but they were severely beaten by only 500 Helvetii cavalry . Apparently Dumnorix was doing everything in his power to delay the supplies . Accordingly , the Romans stopped their pursuit and headed for the Aedui town of Bibracte . The tables were turned , and the Helvetii began to pursue the Romans , harassing their rear guard . Caesar chose a nearby hill to offer battle and the Roman legions stood to face their enemies . In the ensuing Battle of Bibracte , the Celts and Romans fought for the better part of the day in a hotly contested battle with the Romans eventually gaining victory after hours of hard fighting . Caesar writes that " the contest long and vigorously carried on with doubtful success . " The defeated Helvetii offered their surrender which Caesar accepted . However , 6 , 000 men of the Helvetian clan of the Verbigeni fled to avoid capture . Upon Caesar ' s orders , other Gallic tribes captured and returned these fugitives , who were executed . Those who had surrendered were ordered back to their homeland to rebuild it , and the necessary supplies were organized to feed them , as they were far too useful as a buffer between the Romans and other northern tribes , such as the Germans , to let them migrate elsewhere . In the captured Helvetian camp , Caesar claims that a census written in Greek was found and studied : of a grand total of 368 , 000 Helvetii , of which 92 , 000 were able - bodied men , only 110 , 000 survivors were left to return home . Campaign against the Suebi . In 71 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 region . Despite the fact that this migration encroached on Sequani land , the Sequani sought Ariovistus ’ allegiance against the Aedui and in 61 BC , the Sequani rewarded Ariovistus with land following his victory in the Battle of Magetobriga . Ariovistus settled the land with 120 , 000 of his people . When 24 , 000 Harudes joined his cause , Ariovistus demanded that the Sequani give him more land to accommodate the Harudes people . This demand ' concerned ' Rome because if the Sequani conceded , Ariovistus would be in a position to take all of the Sequani land and attack the rest of Gaul . Following Caesar ’ s victory over the Helvetti , the majority of the Gallic tribes congratulated Caesar and sought to meet with him in a general assembly . Diviciacus , the head of the Aeduan government and spokesmen for the Gallic delegation , expressed concern over Ariovistus ’ conquests and 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 the 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 declare war on the Suebi tribe . Caesar said that he could not ignore the pain the Aedui had suffered and delivered an ultimatum to Ariovistus demanding that no German 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 are 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 . Caesar , learning that Ariovistus intended to seize Vesontio , the largest town of the Sequani , commenced marching his troops toward Vesontio . Some of Caesar ’ s officers held their posts for political reasons only and had no war experience . Consequently they suffered from poor morale which threatened Caesar ’ s campaign . Caesar challenged the officers and their legions saying that the only legion he could trust was the 10th . With their pride on the line , the other legions followed the 10th ’ s lead determined not to be out done . Consequently , Caesar arrived in Vesontio before Ariovistus . Ariovistus sent emissaries to Caesar requesting a meeting . They met under a truce at a knoll in the plain . The truce was violated when Caesar learned that German horsemen were edging towards the knoll and throwing stones at his 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 successfully traded with Ariovistus . Insulted , Ariovistus threw the envoys in chains . Ariovistus marched for two days and made camp two miles behind Caesar thus cutting off Caesar ’ s communication and supply lines with the allied tribes . Unable to entice Ariovistus into battle , Caesar ordered a second smaller camp to be built near Ariovistus ’ position . After the camp was completed Caesar again challenged Ariovistus and was rewarded when Ariovistus attacked the smaller camp and was repulsed . 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 Germans 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 German line broke and began to flee . Most of Ariovistus ’ 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 camped near the Rhine returned home . Caesar was victorious . Campaign against the Belgae . In 57 BC Caesar once again intervened in an intra - Gallic conflict , marching against the Belgae , who inhabited the area roughly bounded by modern - day Belgium and had recently attacked a tribe allied with Rome . His army suffered a surprise attack in the battle of the Sabis while it was making camp near the river Sambre and came close to being defeated . The swiftness of Boduognatus ' sudden massed attack , the speed of his allied native footmen ( Atrebates and Virumandui ) together with the ferocity and skill at arms of his heavily armed Nerviians had completely routed Caesar ' s skirmishers and cavalry , overwhelmed his front and very nearly succeeded in taking the Roman camp and capturing Caesar himself . Caesar admits to losing all of his standards and most his centurions dead or felled by wounds . He himself was forced to take up a shield and personally rally his forces which were then threatened with envelopment and massacre . The strong stand by the adjoining X legion and the prompt arrival of the reinforcements enabled Caesar to regroup , redeploy and eventually envelop the Nervii once the Atrebates and Viromandui were stopped , worn down and put to flight . Caesar remarked that the warlike Nervii refused to yield their ground even after the Atrebates and Virumandui had been put into disarray . When finally surrounded by Roman reinforcements the Nerviians continued fighting as a pitiless hail of missiles rained down on them from the many archers and peltasts Caesar had brought from overseas . The peltasts , slingers and archers were brought for the specific purpose of confounding the Gallic proclivity for shield wall tactics , mass attack and / or individual close combat . The Nervii were especially renowned for skills at warfare . They ruled and subsisted by warfare and by taxing their dependent and client tribes while adhering to a heroic hoplitic tradition . These Gallic conventions were something Caesar exploited as often as he could . Together with Caesar ' s prudent and unabashed use of fixed projectile weapons like the ' scorpian ' and light ballista , the archers and peltasts took a heavy toll on the densely packed Nervii who themselves shunned all projectile weapons but the lance . It is recorded in Caesar ' s war commentaries that as the battle raged , the Nervii caught Roman javelins in flight and hurled them back at legionnaires and that although all were eventually slain , not one of the Nervii was seen to flee . As the grim fighting wore on , the Nervii refused to yield and mounds of the fallen formed ramparts and Boduognatus ' fighters fought from atop these hills of dead , clashing with the pressing Roman ranks again and again . The skill with which the veteran Roman legions executed their well practiced ' pilum ' barrage and gladius and scutum counter - attacks together with the prudent use of missile weapons was instrumental in defeating the skillful and daring Nervii and associated Belgae . The Belgae suffered heavy losses and eventually surrendered when faced with the destruction of their towns . The Nervii were severely mauled and forced to flee ; thereby all former client tribes surrendered to Caesar or likewise fled . Their absence gave Caesar control of most of what is now Belgium . Punitive expeditions . The following year , 56 BC , Caesar turned his attention to the tribes of the Atlantic seaboard , notably the Veneti tribe in Armorica ( modern Brittany ) , who had assembled a confederacy of anti - Roman tribes . The Veneti were a seafaring people and had built a sailing fleet in the Gulf of Morbihan , requiring the Romans to build galleys and undertake an unconventional land and sea campaign . Eventually Caesar was able to subdue these tribes after a protracted land and sea campaign . Caesar took his forces across the Rhine in 55 BC in a punitive expedition against the Germans , though the Suebi , against whom the expedition was mounted , were never engaged in battle . That same year , he then crossed the English Channel with two legions on his ships to mount a similar expedition against the Britons . The British adventure nearly ended in disaster when bad weather wrecked much of his fleet and the unfamiliar sight of massed chariot s caused confusion among his forces . Caesar did manage to secure a promise of hostages , though only two of them were actually sent . He withdrew but returned in 54 BC with a much larger force that successfully defeated the powerful Catuvellauni and forced them to pay tribute to Rome . The expeditions had little lasting effect , but were great propaganda victories for Caesar , keeping him in the public eye at home . The campaigns of 55 BC and early 54 BC have caused controversy for many centuries . They were controversial even at the time among Caesar ' s contemporaries , and especially among his political opponents , who decried them as a costly exercise in personal aggrandizement . In modern times , commentators have been sharply divided between critics of Caesar ' s nakedly imperialist agenda and defenders of the benefits that the expansion of Roman power subsequently wrought in Gaul . Consolidation and Gallic offensives . Discontent among the subjugated Gauls prompted a major uprising in the winter of 54 – 53 BC , when the Eburones of north - eastern Gaul rose in arms under their leader Ambiorix . Fifteen Roman cohort s were wiped out at Atuatuca Tungrorum ( modern Tongeren in Belgium ) and a garrison commanded by Quintus Tullius Cicero narrowly survived after being relieved by Caesar in the nick of time . 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 uprising was , however , merely the prelude to a much bigger campaign led by Vercingetorix , chief of the Arverni tribe of central Gaul , who successfully united many Gallic tribes and states under his leadership . Recognizing that the Romans had an upper hand on the battlefield due to their panoply and training , he declined to give battle against them and instead fought a " scorched earth " campaign to deprive them of supplies . Caesar hurriedly returned from Italy to take charge of the campaign , pursuing the Gauls and capturing the town of Avaricum ( modern city of Bourges ) but suffering a defeat at Gergovia . Vercingetorix , instead of staying mobile and in the open , chose to hold out at Alesia ( see Battle of Alesia ) . Caesar successfully besieged him and beat off a huge Gallic relief force who ran out of food and had to disperse . This effectively marked the end of the Gallic Wars , although mopping - up actions took place throughout 51 BC . A number of lesser rebellions took place subsequently , but Roman control of Gaul wasn ' t seriously challenged again until the 2nd century AD . The Gallic Wars in literature and culture . The primary historical source for the Gallic Wars is Caesar ' s " Commentarii de Bello Gallico " in Latin , which is one of the best surviving examples of unadorned Latin prose . It has consequently been a subject of intense study for Latinists , and is one of the classic prose sources traditionally used as a standard teaching texts in modern Latin education . The Gallic Wars have become a popular setting in modern historical fiction , especially that of France and Italy . Claude Cueni wrote a semi - historical novel " The Caesar ' s Druid " about a fictional Celtic druid , servant of Caesar and recorder of Caesar ' s campaigns . Morgan Llewelyn also wrote a book " Druids " about a Celtic druid who assisted Vercingetorix in his campaign against Julius Caesar . Similarly , Norman Spinrad ' s " The Druid King " follows the campaigns from Vercingetorix ' s perspective . In addition , the comic " Astérix " is set shortly after the Gallic Wars , where the titular character ' s village is the last holdout in Gaul against Caesar ' s legions . The TV series Rome begins during the conquest of Gaul and lead protagonists , Lucius Vorenus and Titus Pullo , are based on two historical centurions who fought during the Gallic Wars in Caesar ' s Legio XIII Gemina and are mentioned in " Commentarii de Bello Gallico " . The historical novel " Caesar " by Colleen McCullough gave a thorough , popular account of the Gallic Wars . The concept album " Helvetios " by Swiss Folk Metal band Eluveitie tells the story of the Gallic Wars through the eyes of the Helvetii .