In the seventh year of the war, Caesar was surprised by the scope and strength of the resistance mounted by Vercingetorix, a leader of the neighboring Arverni, who was able to rally a number of Gallic civitates and tribes in a united effort to halt the Roman conquest of Gaul.
Haeduan loyalties during this time appear to have been divided; the Aedui had been allies of Rome and enemies of the Arverni at least since the 120s BC, but Caesar was aware of opposing pro- and anti-Roman factions within the civitas from the beginning of the war.
Aeduan law sought to limit the dynastic accumulation of power within a family by prohibiting a man from holding the vergobrecy if a close relative had within a specified period of time.
Caesar claims that he did not want to involve himself with an internal political matter, and he could ill afford to turn his attention from Vercingetorix, but the instability of the Haedui and an impending civil war among what had long been Rome's staunchest ally in central Gaul warranted his presence.
After reviewing the case and learning that the priests[2] had already ratified the election of Convictolitavis, Caesar rejected the claim of Cotus and hastened back to his army.