Though the Haedui made once more fair promises, it might be foreseen that, if the blockade should still be prolonged without result, they would openly range themselves on the side of the insurgents and would thereby compel Caesar to raise it; for their accession would interrupt the communication between him and Labienus, and expose the latter especially in his isolation to the greatest peril.

Caesar was resolved not to let matters come to this pass, but, however painful and even dangerous it was to retire from Gergovia without having accomplished his object, nevertheless, if it must be done, rather to set out immediately and by marching into the canton of the Haedui to prevent at any cost their formal desertion.
Caesar Defeated before Gergovia Before entering however on this retreat, which was far from agreeable to his quick and confident temperament, he made yet a last attempt to free himself from his painful perplexity by a brilliant success.

While the bulk of the garrison of Gergovia was occupied in intrenching the side on which the assault was expected, the Roman general watched his opportunity to surprise another access less conveniently situated but at the moment left bare.

In reality the Roman storming columns scaled the camp-wall, and occupied the nearest quarters of the camp; but the whole garrison was already alarmed, and owing to the small distances Caesar found it not advisable to risk the second assault on the city-wall.
He gave the signal for retreat; but the foremost legions, carried away by the impetuosity of victory, heard not or did not wish to hear, and pushed forward without halting, up to the city-wall, some even into the city.

But masses more and more dense threw themselves in front of the intruders; the foremost fell, the columns stopped; in vain centurions and legionaries fought with the most devoted and heroic courage; the assailants were chased with very considerable loss out of the town and down the hill, where the troops stationed by Caesar in the plain received them and prevented greater mischief.