The Battle of Alesia, 52 BC

Alesia was the battle that effectively finished the conquest of Gaul. It features in our ranking of the greatest sieges in history, and it was a feat of engineering as much as of arms. For weeks Caesar's legions dug and built until they lived inside a ring of their own making, with one enemy starving in front of them and another, far larger, gathering behind. Then, in a few days of fighting on both faces of the ring at once, they beat both.³

The Gallic revolt

Caesar had been campaigning in Gaul since 58 BC and believed the country beaten. In the early months of 52 BC it rose again under a young noble of the Arverni, Vercingetorix, who took the title of king and was named general of the confederate tribes. He fought a new kind of war, harassing Caesar's supply lines and refusing battle on ground that suited the Romans. Caesar stormed and sacked the town of Avaricum, but at Gergovia, the Arverni's own hill fort, his assault was thrown back. Soon even the Aedui, Rome's oldest allies in Gaul, joined the revolt.⁴

At a council at Bibracte the tribes confirmed Vercingetorix as supreme commander. He tried to finish the war with his cavalry, sending it against Caesar's marching column, but Caesar's German horsemen broke it, and the Gallic army fell back in disorder. Vercingetorix led it, by Caesar's count some 80,000 men, into Alesia, a hilltop town of the Mandubii in what is now Burgundy, and waited for Gaul to come to his rescue. Caesar followed, killing some 3,000 of the rearguard on the way, and the next day pitched camp before the town.⁵

The armies

Caesar had ten legions with him, reinforced by German cavalry and light infantry. Britannica puts the whole force at an estimated 60,000 men. The Gallic numbers come almost entirely from Caesar himself: 80,000 picked men shut up in Alesia, and a relief army of about 250,000 foot and 8,000 horse. Plutarch, writing over a century later, raises them to 170,000 and 300,000. Modern historians generally treat these figures as inflated, but Caesar was clearly outnumbered on both fronts.⁶

The ring of works

Alesia stood on a high hill, its foot washed by rivers on two sides, with a plain about three miles long in front of it and other hills of equal height all around. Caesar judged it could be taken only by blockade. His men began a line of siege works around the town with a circuit of 11 Roman miles and 23 forts, held by pickets by day and strong guards by night.⁷

Before the line was closed, Vercingetorix sent his cavalry out by night through a gap in the works, with orders to ride to every tribe and raise all men able to bear arms. He had grain for about thirty days. When Caesar learned of this from deserters, he made his works far stronger. In front he dug a trench 20 feet wide with vertical sides. Four hundred paces behind it came two more trenches 15 feet wide, the inner one flooded from the river where the ground allowed, and behind them an earth rampart with a palisade 12 feet high, crowned by a breastwork and towers every 80 feet.⁸

In front of all this the soldiers laid out a field of traps, and gave them grim nicknames. Rows of sharpened branches sunk in trenches were the cippi, the gravestones. Pits hiding fire-hardened stakes, set in diagonal rows, were the lilia, the lilies, for their shape. Foot-long logs with iron hooks buried all over the ground were the stimuli, the spurs. Then Caesar built a second line of the same kind facing outward, with a circuit of 14 miles, to hold off the army that was coming. His legions now stood between two walls, ready to fight in both directions.⁹

Hunger inside the walls

The thirty days passed and no help came. Inside Alesia the chiefs met in council. Some urged surrender, others a last sortie. Caesar records the speech of an Arvernian noble, Critognatus, who proposed that they should do what their ancestors had done when the Cimbri invaded, and live on the bodies of those too old or weak to fight rather than yield. The council chose a less terrible course first. The Mandubii, the people whose town it was, were driven out with their wives and children. They came to the Roman lines begging to be taken as slaves and given food, and Caesar refused to let them through.¹⁰

Three days of battle

At last the relief army arrived and camped on a hill outside, less than a mile from the Roman works. Its command was shared by four leaders: Commius of the Atrebates, the Aeduans Viridomarus and Eporedorix, and Vercassivellaunus of the Arverni, Vercingetorix's cousin. On the first day the Gallic cavalry filled the plain, while the men in Alesia filled in the first Roman trench and made ready to break out. The cavalry fight lasted from noon almost to sunset, in full view of both armies, until Caesar's German horsemen charged in a mass and routed the Gauls.¹¹

A day later the relief army attacked at midnight with ladders and hurdles, shouting to warn the town, and Vercingetorix led his men out against the inner line at the same moment. In the dark they ran into the stakes and pits and the bolts of the Roman artillery. Mark Antony and Gaius Trebonius brought troops from quieter forts to the threatened points, and by dawn both attacks had failed.¹²

The third attack was the most dangerous. Local guides showed the Gauls a camp on a hill to the north that the works could not fully enclose, sited on sloping ground and held by two legions. Vercassivellaunus marched there by night with 60,000 picked men, hid behind the height, and attacked at midday, while the rest of the relief army demonstrated against the plain and Vercingetorix stormed the inner line. The Gauls threw earth over the traps and climbed the rampart. Caesar sent Labienus with six cohorts to the hill, then led reserves himself. His men knew him from afar by his cloak, which he wore in battle as a mark.¹³

The decisive blow came from outside the works. Caesar sent part of his cavalry around the outer line to fall on the attackers from behind. As the cohorts charged, the Gauls saw horsemen in their rear and broke. Vercassivellaunus was taken alive, and Caesar says 74 war standards were brought to him. Few of the attackers got back to their camp. Watching the slaughter from the walls, the men in Alesia gave up their assault, and that night the great relief army scattered, with the Roman cavalry cutting down its rearguard.¹⁴

Surrender

The next day Vercingetorix called a council. He had undertaken the war, he said, not for himself but for the freedom of all, and he offered himself to the chiefs to be killed or handed over alive. Caesar demanded the surrender of their arms and their leaders and sat in front of his camp to receive them. Plutarch tells the scene more grandly. Vercingetorix put on his finest armor, rode out of the gate on a decorated horse, circled once around the seated Caesar, then leapt down, threw off his armor and sat silent at Caesar's feet.¹⁵

Caesar kept back the Aedui and the Arverni, hoping to win their peoples back through them, and gave the rest of the prisoners to his army as plunder, one to each soldier. He then restored some 20,000 captives to the Aedui and Arverni, who submitted. When his dispatches reached Rome, the Senate voted a public thanksgiving of twenty days.¹⁶

The end of free Gaul

Alesia did not quite end the Gallic Wars, but it was their last major battle. Roman troops spent the next two summers stamping out the last pockets of resistance, and the whole of Gaul passed under Roman rule. For Caesar the victory brought fame, wealth and a veteran army devoted to him, the instrument he would soon turn against his rival Pompey and the Republic itself.¹⁷

Vercingetorix lived for six more years as a prisoner in Rome. He was led in chains in Caesar's triumph and executed in 46 BC.¹⁸ › Battle of Pharsalus, 48 BC

Finding Alesia

For centuries the site was thought to be Mont Auxois, above the village of Alise-Sainte-Reine in Burgundy, near the source of the Seine. In 1855 a rival theory placed Alesia at Alaise in the Doubs, and a fierce scholarly quarrel followed. Napoleon III settled it his own way. On his orders the Commission de Topographie des Gaules excavated at Alise-Sainte-Reine from April 1861 to September 1862, located the ditches of Caesar's siege lines around the hill and found large quantities of weapons.¹⁹

In 1865 the emperor raised a statue of Vercingetorix about seven meters high on the hill, near the supposed site of the town. Later digs on the plateau uncovered the Gallo-Roman town of Alesia that grew up on the site of the Gallic stronghold.²⁰ › Julius Caesar