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.

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.

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.

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.

[4] 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.

[5] 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.

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.