In 58 BC, following his first consulship in 59 BC, Julius Caesar engineered his own appointment as proconsul (governor) of three Roman provinces by the First Triumvirate. These were Cisalpine Gaul (northern Italy), Illyricum (on the eastern coast of the Adriatic coast) and Gallia Narbonensis (in southeastern France and the rest of France's Mediterranean coast). Although the proconsular term of office was meant to be one year, Caesar's governorship was for an unprecedented five years. He also had the command of four legions.
Caesar engaged in the Gallic Wars (58-50 BC), which led to his conquest of Gaul beyond Gallia Narbonensis. When the Helvetii, a federation of tribes from what is now Switzerland, planned a migration to the Atlantic coast through Gaul, Caesar went to Geneva and forbade the Helvetii to move into Gaul. While he went to Gallia Cisalpina to collect three other legions, the Helvetii attacked the territories of the Aedui, Ambarri, and Allobroges, three Gallic tribes, which called for Caesar’s help. Caesar and his Gallic allies defeated the Helvetii. The Gallic tribes then asked for Caesar to intervene against an invasion by the Suebi, a Germanic tribe. Caesar defeated the Suebi. In 57 BC he intervened in intra-Gallic conflicts and marched on the Belgae of northern Gaul. From then on he conquered the Gallic peoples one by one. His successes in Gaul brought Caesar political prestige in Rome and great wealth through the spoils of wars and the sale of war captives as slaves.
After his initial successes Caesar had to confront a number of Gallic rebellions which threatened his control over Gaul.
In the winter of 54–53 BC the Carnutes (who lived between the rivers Seine and Loire in central France) killed Tasgetius, a pro-Roman king who had been installed by Caesar. Caesar sent one legion to winter there. Soon after, the previously pacified Eburones (who lived in the Ardennes region of Belgium and part of northern France), commanded by Ambiorix, rebelled and destroyed the Legio XIV under the command of Quintus Titurius Sabinus in a carefully planned ambush. This was the first clear Roman defeat in Gaul and inspired widespread national sentiments and rebellion. The Eburones, obtained the support of the Atuatuci (from eastern Belgium), the Nervii (from central Belgium) and numerous minor tribes. They besieged the camp of Quintus Cicero. The siege lasted two weeks. Cicero managed to inform Caesar about this by sending a Nervian noble to him with a letter. This siege was difficult for Cicero because the Gauls had learnt Roman siege techniques and built siege machines similar to those of the Romans. Caesar undertook a forced march from Samarobriva (Amiens, in northern France) with two legions and defeated the besiegers. He made Samarobriva his headquarters. However, the Senones (who lived in an area of the River Seine in northern France) rebelled and were supported by many Gallic tribes. Only the Aedui and Remi remained loyal to Rome. Moreover, the Treveri (from north-eastern Gaul) attacked the legate Titus Labienus, who managed to defeat them, killing their leader.
Caesar levied two more legions and received another one from Pompey. This brought the number of his legions in Gaul to ten. The Treveri obtained the support of the Eburones, Nervii and Atuatuci. On the western front, the Senones, the Carnutes and other nearby peoples continued their rebellion. Caesar made a lightning move on the Nervii, ravaging their fields and seizing a large amount of cattle. The Nervii, caught by surprise, surrendered. Caesar then turned west against the Sernones and Carnutes. They negotiated for peace with the mediation of the Aedui and the Remi. Only Acconus, a seditious prince, was chained. He was later executed as a warning to Gaul. Caesar then turned against the Treveri, the Eburones and their allies. He marched on the Menapi with five legions without baggage. The Menapi hid in the forests. Caesar split his army into three columns and burned many villages and seized much of the cattle. The Menapi surrendered. Meanwhile, Labienus quickly moved on the Treveri with 25 cohorts and the cavalry and without baggage. He defeated them by a river in Belgium and installed a pro-Roman leader. After a second punitive expedition in Germania, Caesar turned his whole army on the Eburones and Ambiorix and sent his cavalry ahead for a surprise attack. The Eburones fled to the forests. Minor nearby tribes sued for peace. Caesar divided nine legions into three columns. One was to control the Menapi, one was to devastate the territories next to the lands of the Atautuci and his pursued Ambiorix. He decided to annihilate the Eburones. Since it was difficult to find them in the forest and the marshes where they hid, he got the Gallic tribes in the region to do this. Villages and farms were burnt, the cattle were killed and all the grain was taken. The survivors starved. Caesar went to Durocortorum (Reims, in north-eastern France) among the Remi. He stationed two legions at the border with the Treviri, two in the land of the Lingones and six among the Senones. He then returned to northern Italy.
Caesar's hard-won and ruthless campaigns were not the end of Gallic unrest.
The Carnuti gathered at Cenabum (modern Orléans) and killed all the Romans who lived there. The news quickly spread around Gaul. Vercingetorix called for a rebellion by his Averni of the Auvergne region of central Gaul. However, some tribal chiefs opposed this and expelled him from Gergovia (Gergovie, in south central Gaul), the capital. Vercingetorix gathered support in the countryside, overthrew them and proclaimed himself king. He sent messages to the nearby peoples in search for support against the Romans. He managed to enlist the Senones, the Parisii from around the River Seine, the Pictones from the Bay of Biscay, the Cadurci from south-western Gaul, the Turones from the area of Tours, the Aulerci from Armorica, an area between the Seine and Loire rivers which included Brittany, the Lemovices from Limousin and Poitou, the Andecavi from Angers on the River Loire, and all the tribes on the coast of the Atlantic. Vercingetorix quickly gathered a large army, sent some troops under Lucterius, the leader of the Cadurci, to the land of the Ruteni (in Aveyron, southern Gaul) and went to the land of the Bituriges (in the Bourges area, central France). Lucterius enlisted three tribes in southern Gaul: the Ruteni, the Nitiobrogi of Agenais (Perigot) and the Gabali of Aquitania.
Caesar hurried to Gallia Narbonensis and placed garrisons among the Ruteni, the Volci Arecomici, the Tolosates of Toulouse and around the capital, Narbo (Narbonne). Lucterius withdrew and Caesar pursued him. This forced Vercingetorix go back to the territory of his Averni. Caesar foresaw this and undertook a forced march to the land of the Lingones, where two legions had been wintering. He then marched with eight legions and seized Vellaunodunum (which belonged to the Senones), Cenabum (the Capital of the Carnuti) and Noviodunum (modern Nouan-le-Fuzelier), which belonged to the Bitiriges. He then seized Avaricum, the largest town of the Bituriges. The town fell after 27 days and 40,000 inhabitants were slaughtered. Even though Vercingetorix had a larger army, he avoided open battle, preferring guerrilla tactics. After the winter Caesar sent Titus Labienus north to suppress a revolt by the Senones and the Parisii with four legions. He marched on Gergovia along the River Elaver (the River Allier, in central France) with six legions. Vercingetorix destroyed all the bridges. The Aedui, long standing Roman allies, sided with the Gallic leader and Caesar temporarily withdrew to deal with them. He then made for Gergovia, where he was defeated before the city walls. Two days later he prepared for a pitched battle, but Vercingetorix declined. Caesar joined Titus Libienus' four other legions. The Aedui rebelled again, killing all the Romans in their area and placing garrisons along the River Loire. Caesar was left with only the Lingones and Remi as allies. Meanwhile, Labienus managed to defeat a coalition of peoples north of the River Loire and rejoined Caesar, escaping attempts to encircle him first by the Bellovaci, who also rebelled, and then the Aedui.,
A general council was summoned at Bibracte (Autun in Burgundy), the capital of the Aedui, once Caesar's loyal supporters. The Treveri, and the Remi and Lingoni (the only two Roman allies left) did not take part. The council declared Vercingetorix, commander of the united Gallic armies. He ordered hostages from all the convened Gallic peoples and the gathering of 15,000 cavalry. He deemed the infantry he had sufficient. He would not accept a pitch battle. The cavalry would destroy the Roman supplies of grain and hay and the Gauls would have to accept to destroy their grain and burn their houses. He sent 10,000 infantry and 800 cavalry of the Aedui against the Allobroges in the Roman province, the Averni and the Gablai (a tribe of Aquitania) against the Elvi and the Ruteni and Cadurci to devastate the territory of the Volci Arecomici. However, these were met by the Roman garrisons which had 22 cohorts.
Caesar joined up with Titus Libienus and went to the Lingoni. He strengthened his troops with Germanic mercenary cavalry units and headed for Gallia Narbonensis. He was attacked by Vercingetorix north-west of Dijon, in eastern Gaul.The attack was repelled by the Roman legions and the Germanic cavalry. The confidence of the rebels was shaken and Vercingetorix decided to withdraw to Alesia, the capital of the Mandubii. Caesar besieged Alesia.
Alesia was an oppidum (fortified settlement) on a lofty hill, with two rivers on two different sides. Due to such strong defensive features, Caesar decided on a siege to force surrender by starvation. Considering that about 80,000 men were garrisoned in Alesia, together with the local civilian population, this would not have taken long. To guarantee a perfect blockade, Caesar ordered the construction of an encircling set of fortifications, a circumvallation, around Alesia. It was eleven Roman miles long (16 km, each mile equivalent to around 1,000 left-foot steps, meaning one stepped with their right, then left) long and had 24 redoubts (towers). While work was in progress, the Gauls carried out cavalry sallies to disrupt the construction. Caesar placed the legions in front of the camp in case of a sally by the infantry and got his Germanic allies to pursue the Gallic cavalry.
Vercingetorix sent the cavalry around Gaul to call the Gallic tribes to war and come to Alesia. When Caesar heard of this from deserters and captives, he dug a trench twenty feet deep (6 metres, 19 ft.) with perpendicular sides, raised all other works four hundred feet (118 m, 388 ft.) from that trench and in between he dug two trenches fifteen feet (4.4 m,14.5 ft.) in length and depth. The inner one was filled with water from the rivers. Behind them he built a twelve feet high (3.5 m, 11.6 ft.) rampart and wall with a parapet and large stakes projecting from the joint between the parapet and the battlement to prevent the enemy from scaling it. This was surrounded with turrets eighty feet apart (23.7 m, 77.7 ft.). The stakes for the palisade were sharpened to a point, sunk into a five-feet deep trench (1.5m, 4.85 ft.), fastened at the bottom so that they could not be pulled up, and placed in five intersected rows. Eight rows, three feet apart (0.89 m, 2.9 ft.), of conic pits which were three feet deep were dug in oblique rows in the form of a quincunx (an arrangement of five objects with four at the corners the fifth at the centre) in front of the palisade.They were called 'cippi.' Stakes sharpened at the top and hardened with fire, the thickness of a man’s thigh, were sunk in the pits and protruded four inches (0.1 m, 3.9 inches) from the ground. The pits were filled with clay and covered over with twigs. One-foot-long stakes (0.3 m) with iron hooks were sunk at small intervals in front of the pits. To prepare for the arrival of the Gallic relief forces he constructed an outer fortification, a contravallation, with the same specifications as protection against external attack by the Gallic relief force. The besiegers were preparing to be besieged.
The food supply of the population of Alesia and the 80,000 soldiers it hosted could not last long. Vercingetorix ordered all the grain to be brought to him and rationed it. The Gauls held a council and it was decided that the old and the sick should leave the town. The inhabitants of the town sent out their wives and children to save food for the fighters, hoping that Caesar would take them as captives and feed them. However, Caesar forbade their being admitted to his fortification. Meanwhile, the relief force arrived and encamped on a hill one mile from the Roman fortification. The next day they encamped near the town. They then attacked the outer fortification. The besieged attacked the inner one. However, this combined attack was unsuccessful. The next day the Gauls attacked at night. Marc Antony and Caius Trebonius, brought in troops from the remotest forts in support of their comrades. At the first light of day, the relief forces, fearing being surrounded by a Roman sally, withdrew. The advance of the besieged, led by Vercingetorix, was delayed by having to fill trenches dug by the Romans. On hearing of the retreat of their comrades they returned to the town.
The Gauls spotted a weakness in the Roman fortification. The north side of a hill could not be included in the Roman works and they placed a camp with two legions on steep and disadvantageous ground (this is indicated by a circle in the figure) . Thus, the Gauls selected 60,000 men and appointed Vercassivellaunus, a near relative of Vercingetorix, to lead the attack on that spot. They marched there before dawn and launched the attack at noon. Vercingetorix made a sally and attacked any part of the inner fortification which seemed weak. Caesar sent Labienus to support the defense of the weak area with six cohorts of cavalry. He sent Brutus with six cohorts of cavalry and then Caius Fabius with a further seven cohorts of cavalry to defend the inner fortification. Finally, leading fresh troops, he joined in. The attack was repelled. Caesar then marched to the assistance of Labienus, drafting four cohorts and ordering part of the cavalry to follow him and part of it to leave the outer fortification and attack the Gallic relief force from the rear. Labienus was on the verge of collapse and informed Caesar of his decision of making a sally as he had been instructed. Caesar hastened. His arrival galvanised the Roman troops, which "lay[d] aside their javelins [and] carr[ied] on the engagement with their swords." The Roman cavalry was suddenly seen at the rear of the Gauls, the Roman troops advanced rapidly and the Gauls fled. They were intercepted by the cavalry and slaughtered. The besieged Gauls were pulled back from the fortification. They fled their camps and Caesar commented that "had not the soldiers been wearied by sending frequent reinforcements, and the labour of the entire day, all the enemy’s forces could have been destroyed." At midnight the Roman cavalry was sent to pursue them. Many were killed and many fled to their lands they came from.
The next day Vercingetorix convened the Gallic council and proposed that he should be killed or surrendered alive to appease the Romans. Caesar ordered the Gauls to surrender their weapons and deliver their chieftains. The chieftains were brought before him and Vercingetorix was surrendered. Captives were given to the Roman soldiers as part of the spoils of war apart from the Aeudi and Arverni, whom he hoped to win over.
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 left pretty much on its own. Marcus Vipsanius Agrippa became its first governor in 39-38 BC. In 39 BC he settled the Ubians on the west bank of the River Rhine and in 38 BC he suppressed a rebellion in Aquitania. He built a radial network of roads centred on Gallic capital, Lugdunum (Lyon). Gallia was divided into three Roman provinces; Gallia Aquitania, Gallia Lugdununensis and Gallia Belgica. Only the Arverni kept their independence thanks to their victory against Caesar at the Battle of Gergovia.
For Caesar, Alesia was an enormous personal success, both militarily and politically. The senate declared 20 days of thanksgiving for this victory, but refused Caesar the honour of celebrating a triumphal parade, the peak of any general's career. Political tension increased, and two years later, in 49 BC, Caesar crossed the Rubicon, which precipitated the Roman Civil War of 49–45 BC, which he won. After having been elected consul, for each of the years of the war, and appointed to several temporary dictatorships, he was finally made dictator perpetuus (dictator for life), by the Roman Senate in 44 BC. His ever-increasing personal power and honours undermined the tradition-bound republican foundations of Rome. More civil wars followed his assassination. The last one was a conflict between Octavian (later known as Augustus) and Marc Antony over who would be the sole ruler of Rome. Octavian won. This led the end of the Roman Republic and the beginning of rule by emperors.
Caesar's commanders followed different paths. Labienus sided with the Optimates, the conservative aristocratic faction Caesar fought against in his civil war, and was killed at the Battle of Munda in 45 BC. Caius Trebonius, one of Caesar's most trusted lieutenants, was appointed consul by Caesar in 45 BC, and was one of the senators involved in Caesar's assassination on the Ides of March (March 15), 44 BC. He was himself murdered a year later. Caius Fabius held up the Pompeian forces at Ilerda until Caesar got there and won the Battle of Ilerda in 49 BC. Decimus Junius Brutus Albinus was entrusted with fleet operations by Caesar during his civil war. He was put in charge of the naval blockade of Massilia (Marseilles) during the Siege of Massilia by Caesar's forces. He built a fleet from scratch and secured the capitulation of the city. He, too, joined the conspiracy to assassinate Caesar. Marc Antony continued to be a faithful supporter of Caesar. He was made Caesar's second in command, as Master of the Horse, in 47 BC during Caesar's second dictatorship and was left in charge in Italy. He mishandled a political issue and deployed troops against a crowd in Rome. Caesar stripped him of his office. He received no appointments in 46 BC and 45 BC. In 44 BC he was elected as Caesar's consular colleague. After Caesar's murder, Antony was part of the Second Triumvirate, an alliance with two other Caesarians, Octavian and Lepidus. Marc Antony and Octavian defeated the forces of the assassins of Caesar in the Liberators' civil war. Later Octavian declared war on Cleopatra VII of Egypt in order to fight Marc Antony, her ally and lover. They were defeated at the Battle of Actium in 31 BC. They went back to Egypt. Marc Antony was defeated again and the two committed suicide.
Vercingetorix was taken prisoner and held as a captive in Rome for the next five years awaiting Caesar's triumph. As was traditional for such captured enemy leaders, he was paraded in the triumph, then taken to the Tullianum and strangled.
Paul K. Davis writes that "Caesar’s victory over the combined Gallic forces established Roman dominance in Gaul for the next 500 years. Caesar’s victory also created a rivalry with the Roman government, leading to his invasion of the Italian peninsula."
For many years, the actual location of the battle was unknown. Competing theories focused first on two towns, Alaise in the Franche-Comté and Alise-Sainte-Reine in the Côte-d'Or. Emperor Napoleon III of France supported the latter candidate, and, during the 1860s, funded archaeological research that uncovered the evidence to support the existence of Roman camps in the area. He then dedicated a statue to Vercingetorix in the recently discovered ruins.
Uncertainty has nevertheless persisted, with questions being raised about the validity of Alise-Sainte-Reine's claim. For example, the site is said to be too small to accommodate even revised estimates of 80,000 men with the Gallic infantry, along with cavalry and additional personnel. It is also alleged that the topography of the area does not fit with Caesar's description. In the 1960s, a French archaeologist, Andre Berthier, argued that the hill top was too low to have required a siege, and that the "rivers" were actually small streams.
Berthier proposed that the location of the battle was at Chaux-des-Crotenay at the gate of the Jura mountains – a place that better suits the descriptions in Caesar's Gallic Wars. Roman fortifications have been found at this site. Danielle Porte, a Sorbonne professor, continues to challenge the identification of Alise-Sainte-Reine as the battle site, but the director of the Alesia museum, Laurent de Froberville, maintains that scientific evidence supports this identification. Classical historian and archaeologist Colin Wells took the view that the excavations at Alise-Sainte-Reine in the 1990s should have removed all possible doubt about the site and regarded some of the advocacy of alternative locations as "...passionate nonsense".
Precise figures for the size of the armies involved, and the number of casualties suffered, are difficult to know. Such figures have always been a powerful propaganda weapon, and are thus suspect. Caesar, in his De Bello Gallico, refers to a Gallic relief force of a quarter of a million, probably an exaggeration to enhance his victory. Unfortunately, the only records of the events are Roman and therefore presumably biased. Modern historians usually believe that a number between 80,000–100,000 men is more credible. The only known fact is that each man in Caesar's legions received a Gaul as a slave, which means at least 40,000 prisoners, mostly from the besieged garrison. Only The Arverni and Aedui prisoners kept their freedom thanks to their valor. The relief force probably suffered heavy losses, like many other armies who lost battle order and retreated under the weapons of the Roman cavalry.