Siege of Alesia, 52 BC

The battle, stage by stage

1. Late summer 52 BC (date uncertain)

   Retreat onto Mont Auxois

   After his cavalry is beaten in a running fight with Caesar's Germanic horsemen somewhere to the north-east (the place is disputed), Vercingetorix falls back with his infantry to Alesia, the hill town of the Mandubii on Mont Auxois. The town sits on a flat-topped hill of about 97 hectares with steep sides, the Ose at its northern foot and the Oserain at its southern; to the west opens the plain of Les Laumes, about three Roman miles long, and hills of equal height ring the other sides. Caesar follows, reportedly killing some 3,000 of the rear guard, and his Germans drive the Gallic horse back into the gates. The Gauls camp on the eastern slope below the town wall behind a ditch and a six-foot dry-stone wall. Caesar's legions — ten or eleven, with auxiliaries; perhaps 40,000 to 60,000 men in all — encamp on the surrounding heights. Approach routes are conjectural.

2. Late summer 52 BC: the lines

   Ringing the hill

   Judging the town too strong to storm, Caesar decides to starve it. By his own account he builds an inner line of 11 Roman miles facing the town, with 23 redoubts, camps at suitable points, a 20-foot ditch on the plain 400 feet in front, two further ditches (one flooded from the river), a rampart and palisade 12 feet high with towers every 80 feet, and fields of hidden traps — stakes, 'lilies' (pits with pointed stakes) and barbed 'spurs'. Then, against the relief army he knows is coming, he builds an outer line of 14 miles. Napoleon III's excavators (1861–1865) traced much of this; the Franco-German excavations of 1991–1997 under Michel Reddé and Siegmar von Schnurbein confirmed the works at Alise-Sainte-Reine but showed that they were less uniform than Caesar describes, followed the ground, and were not continuous everywhere. Camps A and B stand on the Montagne de Flavigny, camp C on the Mont de Bussy and camp D at the foot of Mont Réa. Before the ring closes, Vercingetorix sends his cavalry out by night to raise all Gaul, with grain for about 30 days.

3. September 52 BC (date uncertain)

   The Mandubii between the lines

   The relief army is late and food runs short. In a council inside the town, the Arvernian noble Critognatus — Caesar reports — even proposes living on the bodies of those unfit to fight. Instead the garrison drives out the Mandubii, the townspeople whose hill it is, with their wives and children. They come to the Roman works and beg to be taken in, even as slaves; Caesar posts guards on the rampart and refuses them. Caesar says no more of their fate; later writers assume most died of hunger and exposure between the lines. Where they waited is not recorded; the block on the slope above the plain is only illustrative.

4. September 52 BC: the relief army

   The relief army and the first cavalry battle

   The relief army arrives under Commius of the Atrebates, the Aedui Viridomarus and Eporedorix, and the Arvernian Vercassivellaunus, Vercingetorix's cousin, and camps on a hill no more than a mile from the Roman lines — traditionally the heights south-west of the plain. Caesar gives it 8,000 cavalry and about 240,000 infantry, Plutarch 300,000; modern historians widely judge these figures inflated, with estimates often in the range of 50,000 to 100,000 or more for the relief army and 20,000 to 80,000 inside the town. The next day the Gallic horse, mixed with archers and light infantry, fill the plain while the garrison comes down and begins filling the inner ditch. The cavalry fight lasts from about noon almost to sunset, in full view of both armies on the heights, until Caesar's Germans charge in a massed body and break the Gallic horse; the archers are cut down and the sortie falls back.

5. September 52 BC: the next night but one

   Night attack on the plain

   After a day spent making hurdles, ladders and grappling hooks, the relief army moves out silently at midnight against the works on the plain, raising a shout to warn the town; Vercingetorix answers with trumpets and leads his men down against the inner line. In the dark the attackers are caught in the traps and struck by slingshot, stones and stakes from the rampart. Mark Antony and Gaius Trebonius, commanding the threatened sectors, bring up men from the outlying forts. Before dawn, fearing a flank attack from the camps on the higher ground, the relief army falls back without breaking through, and the garrison, still working through the ditches, returns to the town.

6. Late September 52 BC: about noon onward

   The assault at Mont Réa

   The Gauls have scouted the weak point: the hill to the north-west, Mont Réa, was too large to enclose, so the camp there stands on gently sloping, unfavorable ground, held by two legions under Reginus and Rebilus. Vercassivellaunus leaves camp in the first watch with a picked force — 60,000 by Caesar's count — hides behind the hill, rests his men, and attacks at noon, while the relief cavalry presses the plain works and Vercingetorix attacks the inner line with hooks, poles and mantlets. The attackers pile earth over the traps and tear at the rampart. Caesar, watching from a vantage point, sends Labienus with six cohorts, then Brutus and Fabius against the inner attack on the steep ground, and finally comes himself, recognized by the color of his cloak, with four cohorts, while part of the cavalry rides round outside the outer line. Labienus gathers 39 cohorts; the cavalry appears in the attackers' rear, and the relief force breaks. Sedulius of the Lemovices is killed, Vercassivellaunus captured, and 74 standards brought to Caesar — all by Caesar's own account. The excavations found a concentration of weapons and ditches at the foot of Mont Réa.

7. The next day (traditionally about 27 September 52 BC; date uncertain)

   Surrender of Vercingetorix

   The relief army disperses in the night, pursued by the cavalry. Next day Vercingetorix tells his council he had fought for the freedom of all, and offers himself to them, to be killed or handed over alive. Caesar, seated in front of his camp at the works, receives the surrender of arms and chiefs; Vercingetorix is delivered to him. Plutarch, writing about 150 years later, has him ride out in his finest armor, circle Caesar and sit silently at his feet; Cassius Dio has him kneel in supplication. The place is unknown; it is drawn on the plain only for illustration. Caesar spares the Aedui and Arverni for political reasons and gives one captive to each of his soldiers. Vercingetorix is kept for six years and executed after Caesar's triumph in 46 BC.