In the spring of 52 BC the Gallic tribes once again rose against Caesar, this time under the leadership of Vercingetorix, a skilled leader. Though the Gauls experienced some success early on, over the summer Caesar succeeded in scattering their army. Recognising his tenuous position Vercingetorix chose to avoid further pitched battles, instead retreating to the Mandubii fort of Alesia, from where he sent cavalry to raise a fresh army.
Caesar’s response was to embark on a massive feat of engineering whereby he encircled Alesia with two lines of fortification and encamped between them. Food ran short in the fort and in desperation Vercingetorix forced out those unable to fight – the old, the sick, the women and the children. Though they begged to be taken into slavery, Caesar refused their pleadings and rejected by both friend and foe, they starved to death between the Gallic and Roman lines.
In September, the Gallic relieving force, estimated to be a quarter of a million strong, arrived at the Roman lines. Both the relieving force and Vercingetorix army flung themselves at Caesar’s fortifications but were repeatedly driven back.
Two of the Roman legions were encamped together beneath a hillside to the north of the fort. Recognising this weakness, 60,000 of the relieving troops were moved round the back of hill under the cover of darkness. The following day they launched an attack from above the camp, while the remainder of the force attacked on the plane and Vercingetorix attacked from within. The Gauls on the hillside poured over the fortifications and the thinly spread legionnaires could do little but hold them at bay, using their pila as spears. Meanwhile Caesar had managed to repulse Vercingetorix and the remaining Gauls and rallying his cavalry charged towards the beleaguered camp. Relieved by their general the Romans launched their pila into the Gallic throng and charged. Caught between the legionaries and the cavalry, the Gauls were slaughtered. Recognising the defeat, Vercingetorix surrendered the following day.