Rome under Julius Caesar won the siege of Alesia in 52 BC1, trapping the Gallic leader Vercingetorix and defeating a huge relief army at the same time. The victory finished the conquest of Gaul and made Caesar the most powerful man in Rome; it is remembered as one of the greatest feats of siege engineering in history.
Alesia in 52 BC was the battle that finished the conquest of Gaul and made Julius Caesar the most powerful man in Rome. It is remembered as one of the greatest sieges in history, a feat of engineering as much as of arms, in which Caesar's army trapped an enemy in front of it and held off another one behind it at the same time.
The Gallic revolt
By 52 BC Caesar had spent years subduing Gaul, but that year the tribes united under a gifted young chieftain, Vercingetorix. After a rare defeat for Caesar at Gergovia2, Vercingetorix pulled his army back into the hilltop stronghold of Alesia, in what is now Burgundy in eastern France, expecting to wait Caesar out.
A siege in two directions
Caesar chose instead to besiege him. His legions built a ring of fortifications around Alesia3, a line of ramparts, ditches and towers called a contravallation, to seal Vercingetorix in and starve him out. Then, learning that a massive Gallic relief army was gathering, Caesar built a second ring facing outward2, a circumvallation, so his own men were sandwiched between the two walls, ready to fight in both directions.
When the relief army arrived, the Romans were badly outnumbered and attacked from inside and outside at once. Ancient writers put the relief force at a quarter of a million3; modern estimates are far lower4, but Caesar was still heavily outnumbered. In days of desperate fighting the outer wall was nearly broken, until Caesar himself rushed reserves to the decisive point while his cavalry struck the relief army from behind and shattered it.
Surrender
With no rescue coming and his people starving, Vercingetorix surrendered. Tradition says he rode out and laid his arms at Caesar's feet.5 The revolt collapsed, Gaul was Roman for good, and Caesar, hailed in Rome with a 20-day thanksgiving, would soon turn his army against Rome itself.
Read the man behind the victory in the life of Julius Caesar, or see Alesia beside the other decisive days in the greatest battles of antiquity.
The conquest of Gaul complete
Alesia was the battle that made Gaul Roman. With Vercingetorix surrendered and the great revolt crushed, organised resistance across Gaul collapsed, and the territory Caesar had spent years campaigning to subdue was finally his. The conquest added an enormous, wealthy region to Rome and opened the Celtic world to Roman roads, towns and language, a Romanisation whose imprint on France would last for centuries. For Caesar himself the victory was just as decisive. It confirmed him as Rome's foremost general and left him commanding a battle-hardened, intensely loyal army, the instrument he would soon turn against the Republic when he crossed the Rubicon in 49 BC4.
