September–October 52 BC · Mandubii territory, Burgundy (Alise-Sainte-Reine) Theater
September–October 52 BC
After the cavalry defeat that forced him to withdraw into Alesia's oppidum, Vercingetorix sent messengers to every tribe in Gaul demanding a relief army — he still commanded 80,000 warriors inside the walls. Caesar's response was the most audacious engineering feat of the ancient world: two concentric rings of fortifications totaling 35 kilometers, with the inner ring (circumvallation) trapping Vercingetorix and the outer ring (contravallation) facing outward against the approaching relief army. The works included trenches, palisades, towers every 24 meters, flooding channels, and fields of concealed iron spikes called lilies. A Gallic relief army of perhaps 250,000 arrived and launched coordinated attacks on the outer ring while Vercingetorix attacked the inner ring from inside. For three days the Romans held both rings simultaneously against overwhelming numbers. On the final day, a massive assault nearly overwhelmed the outer ring at a weak point in the hills; Caesar personally led reinforcements wearing his red cloak so his soldiers could recognize him, and the assault was broken. Vercingetorix surrendered the next morning.
Commanders