In September 52 BC, Julius Caesar had a problem. He was deep inside Gaul (modern day France) besieging his last great Gaul enemy, Vercingetorix, at the latter's fort of Alesia. With his force of around 60,000 infantry and cavalry, Caesar built a second wall around Vercingetorix's fort in order to starve his foe into surrender.
For a time, it looked like Caesar was succeeding.
Unable to feed his warriors, Vercingetorix forced the sick, old, children, and women out of Alesia, hoping they would be spared by Caesar and allowed through the Roman lines. Instead, Caesar saw an opportunity to strike at his enemy's morale. He did not accost the civilians, but instead left them to starve in view of their families who had remained inside Alesia. As Caesar recalls in his Commentaries on the Gallic War, "When they came up to our fortifications, they wept and begged the soldiers to take them as slaves and give them something to eat. But I had guards posted all along the rampart with orders not to allow any of them inside our lines."
But then everything changed as a massive relief force of numerous Gaul tribes arrived. Caesar was now surrounded on all sides, facing 70,000 warriors inside Alesia and 100,000 warriors outside. His fortifications thus became a defensive fortress rather than an offensive siege works. And the attacks came fast and furious, day and night; Vercingetorix acted in concert with his allies outside Alesia in order to attack the Romans from front and rear at their weakest points.
Caesar's only advantage was the superior training and professionalism of his forces and commanders. Reinforcing weak points, using cavalry maneuvers to harass enemy archers, and sucking Gaul infantry into spiked pits outside his walls, the future dictator kept his enemy from breaching his lines.
Still, when the final attack came, it was brutal. The Gauls attacked on a sloping hill and from inside Alesia, nearly breaking the Roman lines. As Caesar describes it, the Romans were only saved by his personal decision to enter the fight at the most crucial moment. Regardless, the courage and determination of his men, perhaps motivated by the knowledge that surrender would lead to a fate worse than death, won the day. The Gaul relief force was pushed from the field and then slaughtered by Roman cavalry that night.
Vercingetorix was forced to surrender shortly thereafter and was taken to Rome to be eventually paraded for Caesar's triumph.
Yet Alesia's true gift to Caesar was its furtherance of his political agenda. Finally, someone had crushed the once omnipotent Gauls who had sacked Rome 338 years earlier. Rome had its hero, and Caesar had his opportunity.