advantageous place to hold, as there was only one way in, and a small body of troops could hold the entrance to the place. Vercingetorix therefore crossed the powerful river Elave (now Allier, a tributary to the Loire) at Nevers, 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. Realizing Vercingetorix's plan, Caesar resolved to trick him and cross under his very nose. Caesar one night camped near the town of Varennes-sur-Allier, where there had previously been a bridge before Vercingetorix had destroyed it. That night, he divided his force into two parts, one part being two thirds of the force, the other being one third of the force. He ordered the larger force to march in six corps as if it were really the full army of six legions. 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 at Varennes, speedily rebuilt the bridge that had been present there. He then sent for the other force, which the 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. Battle Five days later Caesar reached Gergovia, the first march being short because most of the troops were tired after marching up the river and back and the last march because the legions arrived at the town. Realizing that its mountainous location made a frontal assault risky, he decided to rely on his superior siege tactics. Upon arriving, Caesar discovered that there was a small hill that the Gauls held that was essential to their holding Gergovia itself. From there, they were able to provide water, grain, and forage. Caesar took this in a night raid and swiftly stationed two legions there. He then linked it to his main camp by digging a double trench, twelve feet (3.6 metres) wide, with a parapet. The result was a barrier that kept the Gauls from their supplies, which they needed desperately. They were forced to subsist on the meager stream that supplied water to Gergovia itself. The loyalty of the Aedui to Rome