Battle of Gergovia - Prelude

Prelude

Vercingetorix had earlier been expelled from Gergovia. In winter 53 BC, whilst Caesar was gathering his forces for a strike against the Gauls, Vercingetorix attacked Gergovia. Caesar states that this left him with a difficult decision, between keeping his forces safe over the winter but showing Roman weakness in defending her allies the Aedui and thus losing their support, or bringing Vercingetorix to open battle but risking running out of supplies - he chose the latter.

Leaving two legions and all his baggage train behind in Agedincum, Caesar led the remaining legions to Gergovia's aid. His sieges of Vellaunodunum, Genabum and Noviodunum en route caused Vercingetorix to lift his siege and march to meet Caesar in open battle at Noviodunum, which Caesar won. Caesar then besieged and captured Avaricum and resupplied there.

Caesar then set out in the direction of Gergovia, which Vercingetorix was probably able to guess once he had divined his direction. The heights of Gergovia itself, stand twelve hundred feet above the plain that they overlook. It is a plateau that is mile and a half long by a third of a mile wide. It was an advantageous place to hold, as there was only one way in, and a small body of troops could hold the entrance to the place. It was a reasonably easy guess to make.

Vercingetorix therefore crossed the river Elave, and started marching up and down the bank, mirroring Caesar's movements, and destroying all the bridges to keep him from crossing. The purpose presumably being to destroy part of his force as he attempted to cross the Elave. Realizing Vercingetorix's plan, Caesar resolved to trick him and cross under his very nose.

Caesar one night camped near the town of Varennes, where there had previously been a bridge before Vercingetorix had destroyed it. That night, he divided his force into two parts, one part being 2/3rds of the force, the other being 1/3rd of the force. However, the larger force he ordered to march in 6 corps, as if it were in fact the full corps. He then ordered it to continue its march south, Vercingetorix, duped, took the bait and followed this part of the force.

Caesar, with the two legions still present at Varennes, speedily rebuilt the bridge that had been present there. He then sent for the other force, which during that next day stole a march on Vercingetorix, and completed a junction with the original force, and crossed the rebuilt bridge. Realizing that he had been duped, Vercingetorix set out south, to beat Caesar to Gergovia