raised by resolution of the national assembly to 15,000 horse.  Caesar with the whole strength of his army after it was reunited at Agedincum took the direction of Besancon, with the view of now approaching the alarmed province and protecting it from an invasion, for in fact bands of insurgents had already shown themselves in the territory of the Helvii on the south slope of the Cevennes.  Alesia lay almost on his way; the cavalry of the Celts, the only arm with which Vercingetorix chose to operate, attacked him on the route, but to the surprise of all was worsted by the new German squadrons of Caesar and the Roman infantry drawn up in support of them.

Caesar in Front of Alesia
Siege of Alesia

Vercingetorix hastened the more to shut himself up in Alesia; and if Caesar was not disposed altogether to renounce the offensive, no course was left to him but for the third time in this campaign to proceed by way of attack with a far weaker force against an army encamped under a well-garrisoned and well-provisioned fortress and supplied with immense masses of cavalry.  But, while the Celts had hitherto been opposed by only a part of the Roman legions, the whole forces of Caesar were united in the lines round Alesia, and Vercingetorix did not succeed, as he had succeeded at Avaricum and Gergovia, in placing his infantry under the protection of the walls of the fortress and keeping his external communications open for his own benefit by his cavalry, while he interrupted those of the enemy.  The Celtic cavalry, already discouraged by that defeat inflicted on them by their lightly esteemed opponents, was beaten by Caesar’s German horse in every encounter.  The line of circumvallation of the besiegers extending about nine miles invested the whole town, including the camp attached to it.  Vercingetorix had been prepared for a struggle under the walls, but not for being besieged in Alesia; in that point of view the accumulated stores, considerable as they were, were yet far from sufficient for his army—­which was said to amount to 80,000 infantry and 15,000 cavalry—­and for the numerous inhabitants of the town.  Vercingetorix could not but perceive that his plan of warfare had on this occasion turned to his own destruction, and that he was lost unless the whole nation hastened up to the rescue of its blockaded general.  The existing provisions were still, when the Roman circumvallation was closed, sufficient for a month and perhaps something more; at the last moment, when there was still free passage at least for horsemen, Vercingetorix dismissed his whole cavalry, and sent at the same time to the heads of the nation instructions to call out all their forces and lead them to the relief of Alesia.  He himself, resolved to bear in person the responsibility for the plan of war which he had projected and which had miscarried, remained in the fortress, to share in good or evil the fate of his followers.  But Caesar made up his mind at once to besiege and to be besieged.  He prepared his line of circumvallation for defence also on its outer side, and furnished himself with provisions for a longer period.  The days passed; they had no longer a boll of grain in the fortress, and they were obliged to drive out the unhappy inhabitants of the town to perish miserably between the entrenchments of the Celts and of the Romans, pitilessly rejected by both.