From the campaign:
An implacable foe has arisen a hero in Gaul. But fear not we shall parade this Vercingetorix in chains before the Senate. Long live the Republic!
Caesar's conquest of the Gallic tribes has gone down in history as a series of great victories culminating in his greatest triumph the siege of Alesia. We know this because Caesar said so in his book :) Our next Stretch Goal after Caesar is his greatest foe Vercingetorix.