In late September, a relief force of eighty thousand Gauls arrived and both Gallic forces attacked the Romans – one from the inside and one from the outside. Caesar sent his cavalry against the relief force while his army fought off an attack from those trying to breakout from the city. Neither Gallic army was able to penetrate the fortifications. The next day Vercingetorix concentrated a new attack force against a weak spot in the inner fortifications. His army successfully broke through but were attacked from behind by Roman cavalry that had ridden around the outer ring to their rear. Caesar, himself, appeared with the troops trying to close the gap and the Romans were ultimately successful.
With their reinforcements routed, and no further hope to break the siege, Silesia surrendered and handed over Vercingetorix to Caesar, who imprisoned him for six years and then paraded him through Rome before his execution.