Battle of Alesia

At Alesia, a hilltop stronghold of the Mandubii in eastern Gaul, Julius Caesar trapped the Gallic leader Vercingetorix in the late summer of 52 BC, generally dated to September. Caesar's army ringed the town with two lines of fortifications, one facing in and one facing out, and beat off both the defenders and a large Gallic relief army. The victory broke the last great Gallic revolt and effectively decided the Gallic Wars.

By 53 BC Caesar had spent five years conquering Gaul for the Roman Republic, often with great brutality. When he began treating Gaul as a Roman province, many tribes feared for their independence and their sacred lands, and over the winter Vercingetorix, king of the Arverni, built an unusually broad coalition. His strategy was to starve the Romans by destroying supplies and attacking foragers rather than meeting them in open battle.

Caesar stormed the stronghold of Avaricum, claiming 40,000 killed, but was beaten at Gergovia, the Arverni's own town, admitting the loss of 700 men including 46 centurions, a figure probably understated. After a cavalry battle in which Caesar's horsemen, including Germanic allies, routed the Gallic cavalry, Vercingetorix withdrew to Alesia and sent riders to summon help from across Gaul.

Rather than assault the steep, river-flanked hill, Caesar decided to starve it out. His soldiers dug an inner ring of works, which Caesar gives as eleven Roman miles long with 23 redoubts, made up of ditches, a palisaded rampart, towers and fields of hidden traps: sharpened stakes, concealed pits and iron hooks. Knowing a relief army was coming, he then built an outer ring of similar design, about fourteen Roman miles round, to face it. Excavations suggest the lines were less continuous than Caesar describes and made use of the terrain, but they worked.

Inside Alesia, food ran short. The townspeople sent their women, children and old people out of the town, hoping the Romans would take them in. Caesar refused, and they were left between the lines to starve.

The relief army arrived and, with the defenders attacking from inside, tried to break through at the same time, first by day and then by night; both attempts failed, with Roman officers including Mark Antony bringing up reserves. The Gauls then found a weak point on the north side, where a hill had forced the Romans to place a camp on poor ground, and sent a picked force under Vercassivellaunus, a relative of Vercingetorix, against it while Vercingetorix attacked from within. The fighting was desperate. Caesar led fresh troops to the threatened sector and sent cavalry round behind the attackers, who broke and were cut down as they fled. The relief army dispersed.

The next day Vercingetorix surrendered. Caesar handed captives to his soldiers as booty, except for the Aedui and Arverni, whose loyalty he wanted to regain. Vercingetorix was held in Rome until Caesar's triumph and executed in 46 BC.

Ancient writers give huge totals for the Gauls: about 328,000 according to Caesar, 400,000 according to Strabo and 470,000 according to Plutarch. Caesar spoke of a relief force of around a quarter of a million, which modern historians regard as inflated; they generally consider between 50,000 and 100,000 more plausible for the relief army, with perhaps 60,000 to 75,000 Romans and allies in all.

Organised resistance in Gaul ended, and the Senate voted 20 days of thanksgiving, though Caesar's enemies kept him from a triumph for the moment. Tensions with them led him to cross the Rubicon in 49 BC and win the ensuing civil war, a road that ended with his assassination. Gaul became formal Roman provinces under Augustus in 27 BC. The site is now generally placed on Mont Auxois above Alise-Sainte-Reine, where Napoleon III sponsored excavations in the 1860s.

Our 100 BCE map shows Gaul, home of the Celts, before Caesar's conquest; by our 1 BCE map it lies within Roman territory, covering modern France.