Drawing; Gergovia in question; Plan of the battle of Gergovia (warning: big picture, takes a while to load)
Caesar - Gallic War- Book VII, 36 - Gergovia
From that position Caesar reached Gergovia in five days' march. On the fifth day a slight cavalry skirmish took place ; and having reconnoitred the position of the city, which was set upon a very lofty height, with difficult approaches on every side, he despaired of taking it by storm, and he determined not to attempt a blockade until he had secured his corn supply. Vercingetorix, for his part, had pitched camp near the town, and posted the contingent of each state separately at short intervals around himself. Every eminence on the ridge from which a bird¹s-eye view was possible had been seized, and the appearance was formidable. He would order the chiefs of the states, whom he had chosen to assist him in council, to assemble at dawn daily at his quarters in case there should seem to be anything to communicate or to arrange. And scarcely a day passed that he did not put to the test, by an encounter of horsemen with archers placed among them, the spirit and the courage of each of his followers. Opposite the town there was a hill at the very foot of the mountain, an exceedingly strong position, precipitous on every side. If our troops secured this they thought they could cut off the enemy at once from great part of their water-supply and from freedom of foraging. The post was held, however, by the enemy with a garrison, albeit not a very strong one. None the less, Caesar marched out of camp in the silence of night, dislodged the garrison before it could be reinforced from the town, and made himself master of the position. He posted two legions there, and ran a double ditch, twelve feet broad in each case, from the greater to the lesser camp, so that even single soldiers could pass to and fro safe from a sudden onset of the enemy.
Drawing of Gergovia
Gergovia in question
Plan of the battle of Gergovia (warning: big picture, takes a while to load)