Battle of Bibracte

The Battle of Bibracte was fought between a Gallic confederation centred around the Helvetii and a Roman army under the command of Gaius Julius Caesar. It was the first major battle of the Gallic Wars.

Battle of Bibracte
Part of the Gallic Wars
Julius Caesar and Divico parley after the battle at the Saône. Historic painting of the 19th century by Karl Jauslin.
Date 58 BC Location Saône-et-Loire, France 46°55′0.001″N 4°1′59.999″E Result Roman victory
Belligerents
Roman Republic	Helvetii Boii Tulingi Rauraci
Commanders and leaders
Gaius Julius Caesar	Divico
Units involved
Legions: Legio VII Legio VIII Legio IX Legio X Legio XI Legio XII	The warriors of the: Helvetii Boii Tulingi Rauraci
Strength
Present: 40,000 troops[1] 25,000–30,000 legionaries unknown number auxiliaries unknown number allied infantry 4,000 allied cavalry Engaged: 30,000 troops[1] 4 legions and auxiliaries	Caesar: 368,000 people: 90,000 warriors 278,000 non-combatants Ancient historians: Pollio: 157,000 people Orosius: 157,000 people Livy: 157,000 people Modern historians: Delbrück: 12,000 warriors Gilliver: 50,000 warriors
Casualties and losses
Unknown	Caesar: 238,000 killed or captured
Location within France Show map of France Battle of Bibracte (Europe) Show map of Europe

Prelude

The Helvetii, a confederation of Gallic tribes from the area of modern day Switzerland, had begun a large scale migration of its peoples in March of 58 BC. They were joined in their migration by elements of other tribal groups; mainly the Boii, Tulingi and the Rauraci. This alarmed the Romans and began the Gallic Wars.^[2]

Julius Caesar, who had been granted a five-year governorship of Illyricum, Gallia Cisalpina and more importantly Gallia Transalpina, grew concerned about a migration of such magnitude. The Helvetii migration threatened to upset the balance in central Gaul and cause a lot of trouble for the Romans and their Gallic allies. Caesar was also looking for an excuse to embark on a military campaign and had 4 legions, 16,000–20,000 legionaries, under his command. Unfortunately for Caesar, three of his legions were at Aquileia in Cisalpine Gaul^{[note 1]} a long way from Gaul proper. He took the one legion in Transalpine Gaul, the Tenth, and marched north to the Rhône. He had his legionaries break down the one bridge across the Rhône at Geneva and started fortifying the northern side of the river. When the Helvetii arrived they tried to negotiate with Caesar, but he told them to return home. They then tried to force a river crossing, but were repulsed by the well dug in Tenth legion. Eventually the Helvetii admitted defeat and marched back towards their homeland, but soon veered off course and took an alternative route through the Jura Mountains into central Gaul. Leaving his senior legate Labienus in command of the defences on the Rhône Caesar travelled to Aquileia and marched his main army toward the lands of the Aedui, Rome's main allies in Central Gaul, recruiting two more legions along the way. Before arriving at the Aedui lands Caesar united his forces; he now had six legions, 25,000–30,000 legionaries, a force of allied cavalry which would soon number 4,000 horsemen, and some light infantry auxiliaries^{[note 2]}. He marched towards the River Saône; here he caught the Helvetii in the middle of a river crossing. Some three-quarters had crossed, but he slaughtered those who had not. Caesar then crossed the river in one day using a pontoon bridge. Next, he followed the Helvetii, but refused to engage in combat, waiting for ideal conditions. Negotiations were attempted, but Caesar's terms were draconian (likely on purpose, as Caesar may have used it as a delaying tactic). Caesar's supplies ran thin around the 20th of June and he was forced to travel towards allied territory in Bibracte, as while his army had easily crossed the Saône, his supply train had not. Bibracte was approximately 18 miles away from their camp to obtain the supplies promised by his allies, the Aedui, in whose lands the Helvetii were crossing. Dumnorix, an Aedui chieftain opposed to the Romans, had been delaying supplies from reaching Caesar's army. The Roman troops were so caught up in the current events of Dumnorix cutting their supplies that the Helvetii used this moment to attack Caesar's rear guard and took full advantage of this opportunity.^[2][4][5]

Battle

A number of Gauls deserted from the allied cavalry commanded by the legate Lucius Aemilius. They joined the Helvetii and informed them of the Roman march. The Helvetti decided to harass Caesar's rear guard which caught the attention of the entire Roman army.^[4] When Caesar observed this, he sent his cavalry to delay the attack. This led to the true start to the Battle of Bibracte. Caesar then placed the Seventh, Eighth, Ninth, and Tenth legions, organized in three battle lines, the regular Roman battle order called triplex acies^{[note 3]}, on a slope of a nearby hill, the top of which he occupied himself, along with the Eleventh and Twelfth legions and all his allies and auxiliaries. His baggage train was assembled near the summit, where it could be guarded by the forces there. The legionaries of the Eleventh and Twelfth started to dig a trench and build a rampart around the bagage. Caesar probably felt it important to keep his recently recruited soldiers busy and wanted the experienced men in the main battle line to know their commander was making sure their possessions were extra safe.^[7]

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, the Helvetii advanced in a close formation with a shield wall in front, they came on in good order, but their attack was checked when the Romans threw several volleys of pila; heavy javelins/throwings pears.^{[note 4]} The Roman missiles killed or wounded a number of warriors while other pila got stuck in the attackers shields. The Roman legionaries cheered, drew their swords and advanced downhill. The Helvetii advance had been halted and now the Romans charged into them with the advantage of coming in from the high ground; 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 four legions of the main battle line drove the Helvetii back down the slope, across the plain towards the hill where their families were and their baggage train sat.^[4][8]

While the legions pursued the Helvetii across the plain between the hills, the Boii and the Tulingi arrived with 15,000 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 redeployed his third line to resist the assault of the Boii and Tulingi, keeping his first and second line committed to chasing the Helvetii.^{[note 5]}

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 whom 110,000 survived the retreat.^[9] 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.

Aftermath

Casualties

Caesar claimed that of the 368,000 Helvetii and allies, only 130,000 got away, of whom 110,000 returned home.^[10] Orosius, probably drawing on the works of Caesar's general Asinius Pollio, gave an original strength of 157,000 for the barbarians, adding that 47,000 died during the campaign.^[10] Strabo states an even lower figure, with only 8,000 escaping the battle, an estimate assessed as plausible by Hans Delbrück.^[10]

Historian David Henige takes particular issue with the supposed population and warrior counts. Caesar claims that he was able to estimate the population of the Helvetii because in their camp there was a census, written in Greek on tablets, which would have indicated 263,000 Helvetii and 105,000 allies, of whom exactly one quarter (92,000) were combatants. But Henige points out that such a census would have been difficult to achieve by the Gauls, that it would make no sense to be written in Greek by non-Greek tribes, and that carrying such a large quantity of stone or wood tablets on their migration would have been a monumental feat. Henige finds it oddly convenient that exactly one quarter were combatants, suggesting that the numbers were more likely ginned up by Caesar than outright counted by census. Even contemporary authors estimated that the population of the Helvetii and their allies were lower, Livy surmised that there were 157,000 overall. But Henige still believes this number inaccurate. Hans Delbrück estimates that there were at most 20,000 migrating Helvetii, of whom 12,000 were warriors.^[11] Gilliver thinks that there were not more than 50,000 men in the Gallic army.^[2]

Also according to Caesar the census totals of the tribes at the start of the war were:

Tribe	Population census
Helvetii	263,000
Tulingi	36,000
Latobrigi	14,000
Rauraci	23,000
Boii	32,000
Total	368,000
Combatants	92,000