The Aedui were allies of Rome, but Dumnorix was a leader of the tribe’s anti-Roman faction, who “...thought it better to be dominated by their fellow Gauls... rather than the Romans.”[1] His brother Diviciacus supported the Aedui's pre-existing alliance with Rome, was a leader of the pro-Roman faction, and would ultimately aid Julius Caesar in his conquest of Gaul.

Orgetorix, a prominent Helvetii chieftain, conspired with Dumnorix, and Casticus of the Sequani to make themselves kings in their own tribes; then by their combined power rule all of Gaul in a Gallic version of the triumvirate.

He built fortifications at Lake Geneva and either requested or demanded that the Aedui, who had been named friend and ally of Rome, supply his soldiers with grain.

Caesar forced the Helvetii to take an alternate path, then inflicted a devastating defeat on the tribe at the Battle of the Arar.

Liscus, the chief magistrate or Vergobretus of the Aedui, revealed to Caesar that Dumnorix was responsible for withholding the supplies and had also been in command of the unit whose flight had cost him the cavalry engagement.

Dumnorix continued to be troublesome, and in 54 BC was one of the Gaulish leaders Caesar proposed to take with him as hostages on his second expedition to Britain, fearing that they might cause trouble in his absence.