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Battle of Alesia summary

The Battle of Alesia or Siege of Alesia took place in September, 52 BC around the Gallic oppidum of Alesia, a major town centre and hill fort of the Mandubii tribe. It was the last major engagement between Gauls and Romans, marking the turning point of the Gallic Wars in favour of Rome. The battle of Alesia can safely be described as marking the end of Celtic dominance in France, Belgium, Switzerland and Northern Italy.

  1. Alesia was a hill-top fort surrounded by river valleys, with strong defensive features. As a frontal assault would have been hopeless, Caesar decided upon a siege, hoping to force surrender by starvation upon the besieged Gauls under Vercingetorix. To guarantee a perfect blockade, Caesar ordered the construction of an encircling set of fortifications, called a circumvallation, around Alesia. Anticipating that a relief force would be sent, Caesar ordered the construction of a second line of fortifications, the contravallation, facing outward and encircling his army between it and the first set of walls. When the Gaulish relief force arrived, strengthening the resolve of the besieged Gauls to resist the Roman besiegers became the besieged.
  2. At the end of September the Gauls, commanded by Commius, attempted to break in by attacking Caesar's contravallation wall. Vercingetorix ordered a simultaneous attack from the inside.
  3. None of the attempts were successful and by sunset the fighting had ended.
  4. On the next day, the Gallic attack was under the cover of night. This time they met with greater success and Caesar was forced to abandon some sections of his fortification lines. The inner wall was also attacked, but the presence of trenches, which Vercingetorix's men had to fill, delayed them enough to prevent surprise.
  5. The swift response of the cavalry commanded by Antony and Gaius Trebonius restored the situation for the Romans. However, by this time, the condition of the Roman army was also weak. Themselves besieged, food had started to be rationed and the men were near physical exhaustion.
  6. On the next day, October 2, Vercassivellaunus, a cousin of Vercingetorix, launched a massive attack with 60,000 men, focusing on a weakness in the Roman fortifications (the circle in the figure) which Caesar had tried to hide, but had been discovered by the Gauls. The attack was made in combination with Vercingetorix's forces.
  7. Caesar sent out orders to his men to simply hold the lines. He personally rode throughout the perimeter cheering his legionaries. Labienus' cavalry was sent to support the defense of the area where the fortification breach was located.
  8. With pressure increasing, Caesar was forced to counter-attack the inner offensive and managed to push back Vercingetorix's men. By this time the section held by Labienus was on the verge of collapse.
  9. Caesar decided on a desperate measure and took more cavalry to attack the relief army from the rear.
  10. Seeing their leader undergoing such risk, Labienus' men redoubled their efforts and the Gauls soon panicked and tried to retreat. As in other examples of ancient warfare, the retreating army was easy prey for the disciplined Roman pursuit.
  11. In Alesia, Vercingetorix witnessed the defeat of his relief force. Facing both starvation and low morale, he was forced to surrender without a final fight. On the next day, the Gallic leader presented his arms to Julius Caesar, putting an end to the siege of Alesia.