Uniting the Gallic Tribes
Vercingetorix succeeded in persuading many Gallic tribes long at war with and independent of one another to lay aside their historical grievances and form an unprecedented unified allied army to resist the Roman conquest together, a rare capacity for tribal alliance and mobilization exceedingly hard to achieve in a Gaul long noted for tribal division, and one that gave Caesar’s conquest of Gaul an unprecedented severe challenge.
The Siege of Alesia and the Surrender
After Vercingetorix withdrew to the fortress of Alesia, Caesar massed his forces to build a double ring of circular works dozens of kilometers long, the inner wall besieging the defenders and the outer wall blocking the Gallic relief army, forming the unique tactical situation of "the besieger himself besieged"; at last the Gallic relief attempt fell short, and Vercingetorix, to save his men’s lives, chose to ride out of the city in person to surrender to Caesar — a scene thereafter repeatedly depicted by nineteenth-century French painters, becoming a classic image of intensely tragic color in French historical narrative.