Alesia September, 52 BC

1. AlesiaSeptember, 52 BC Strategic Context Julius Caesar considers Gaul secure until it revolts under the leadership of Vercingetorix, an Arverni chieftain. Vercingetorix does not rely on an impulsive, barbarian offensive strategy as Caesar expects. Instead, the Gauls do not allow a decisive battle to take place for fear it will be a decisive defeat, and fight a partisan war by retreating and destroying everything behind them. Caesar grows impatient, especially after the failed assault against the fortress of Gergovia and the inconclusive skirmish at the Vingeanne. Vercingetorix retires to Alesia and Caesar follows; it appears Vercingetorix, pressured by his allies, is finally giving battle. Stakes + A Roman victory would crush the Gallic revolt and remove Vercingetorix as a nuisance for good. + A Gallic victory would heighten the insurrection and threaten Roman control over the entire region. By Jonathan Webb, 2009

2. Alesia, 52 BCStrength • Romans • Well • Gauls • Well • Julius Caesar • Vercingetorix • 150,000 infantry • 40,000 infantry • 15,000 cavalry • 23,000 cavalry By Jonathan Webb, 2009

3. Roman Empire c. 52 BC

4. The fort of Alesia sits atop the steep western hill of Mount Penneville, surrounded by rivers, valleys, and then hills a little further out, making approach difficult from three sides. The steepest and most elevated terrain is to the north in the form of Mount Rea and Mount de Bussy. The flattest terrain is to the southwest where the Heights of Mussy-le-Fosse give way to the Plain of Laumes. 0 1 2 3 km Romans (Caesar) Mount Rea Mount de Bussy Rabutin River Oze River Alesia Brenne River Ozerain River Plain of Laumes Mount Penneville Heights of Mussy-le-Fosse Mount de Flavigny Gauls (Vercingetorix)

5. Vercingetorix’s force within Alesia runs out of supplies and hope just as a massive Gallic relief army arrives, led by four other chieftains. Some Gallic infantry rush out to begin filling the wide ditch in anticipation of an immediate assault by the relief army. However, the relief army is unprepared to make such a hasty assault after a long journey so Caesar sends out his cavalry to challenge the Gallic relief army’s small cavalry contingent. The two cavalry forces exchange blows all afternoon until the Roman cavalry finally defeat the Gauls and chase them from the field, discouraging the besieged Gauls as Caesar intended. The Romans begin construction on lines of contravallation, extensive barriers to prevent the Gauls in Alesia from escaping and protect the Romans from any attack by them. These fortifications face inward and consist of a double ditch backed by a 12-foot high rampart, missile towers, and macabre traps, many invented by Caesar and his men, littered everywhere possible. Vercingetorix sends his cavalry to halt construction of such a ruthless line of defence but Caesar’s cavalry drive them back to Alesia; construction continues until completion. At midnight, the Gallic relief army launches an attack on the western side of the Roman fortifications. Caesar is able to transfer reinforcements to the threatened sectors and repel the attack decisively, but only after heavy fighting from behind his extensive lines of circumvallation. Vercingetorix tries to coordinate his attack with the relief army but only learns of the attack when the Romans do. His infantry are therefore delayed by the first wide ditch and reach battle too late to aid the relief army’s efforts. Gauls on both sides of Roman lines retire to their camps. Caesar surrounds Alesia with his entire force, and builds some earthen walls and a wide ditch on the western plain. He decides to blockade rather than assault the city because of its naturally fortified position and the large Gallic force within it. At first, Vercingetorix encamps his force on Alesia’s slopes because he expects Caesar to attack from the east before reinforcements can be summoned. The same night the Romans complete construction, Vercingetorix sends his cavalry away for two reasons: there are insufficient supplies to feed the riders along with their animals. and reinforcements must be summoned immediately. The exhausted Romans are unable to intercept the Gallic cavalry but their punishing defences still inflict heavy casualties. Caesar orders a second line of fortifications, lines of circumvallation, to be built to defend against an attack from a Gallic relief army. This second line is just as savage and fortified as the first except this one faces outward. Romans Gauls Infantry Infantry Cavalry Cavalry 0 1 2 3 km Gauls (Vercingetorix) 150,000 infantry 23,000 cavalry Romans (Julius Caesar) 40,000 infantry 15,000 cavalry Romans (Caesar) Symbol guide Mount Rea Mount de Bussy Rabutin River Oze River Vercingetorix Alesia Brenne River Ozerain River Plain of Laumes Mount Penneville Heights of Mussy-le-Fosse Commius/ Vercassivellaunus/ Viridomarus/ Epoderix Landmarks Mount de Flavigny Gauls (Vercingetorix)

6. The Gauls scout the impressive Roman lines for weaknesses before considering another assault. The Gallic leaders determine the most vulnerable sector to be the northwest corner where a steep hill prevents proper fortification. Under cover of night, Vercassivellaunus leads a strong infantry force behind the nearest hill; he strikes against this vulnerable place in daylight while the rest of the relief army parades in front of their camp. This massive attack is somehow coordinated with Vercingetorix who simultaneously sends his infantry against three sides of the Roman lines of contravallation, one of which dismisses the attack almost at once. Caesar sends reinforcements to wherever is needed at that very moment. At midnight, the Gallic relief army launches an attack on the western side of the Roman fortifications. Caesar is able to transfer reinforcements to the threatened sectors and repel the attack decisively, but only after heavy fighting from behind his extensive lines of circumvallation. Vercingetorix tries to coordinate his attack with the relief army but only learns of the attack when the Romans do. His infantry are therefore delayed by the first wide ditch and reach battle too late to aid the relief army’s efforts. Gauls on both sides of Roman lines retire to their camps. Fighting is desperate in all sectors, especially in the northwest where the Romans are under attack from two sides. Caesar’s fortifications and his presence prove their worth everywhere. His timely appearance in the southern sector inspires his infantry to defeat the Gauls and end this threat. He is then able to shift reinforcements over to help the northwest sector hold while he sends his cavalry outside the fortifications. The Roman cavalry sweep across the flank and rear of the heavily committed Gallic infantry, scattering the entire force. Vercingetorix sees the attack has failed and once again retires to Alesia. Vercingetorix summons his subordinates to a council and proposes a surrender. The Gauls have suffered grave casualties, have not yet breached the Roman fortifications while Alesia has no supplies. None of his subordinates object. Vercingetorix personally surrenders to Caesar while nearly every Gallic tribe involved also capitulate. Romans Gauls Infantry Infantry Cavalry Cavalry 0 1 2 3 km Gauls (Vercingetorix) 150,000 infantry 23,000 cavalry Romans (Julius Caesar) 40,000 infantry 15,000 cavalry Romans (Caesar) Vercassivellaunus Symbol guide Mount Rea Mount de Bussy Rabutin River Oze River Vercingetorix Alesia Brenne River Ozerain River Plain of Laumes Mount Penneville Heights of Mussy-le-Fosse Commius/ Vercassivellaunus/ Viridomarus/ Epoderix Commius/ Viridomarus/ Epoderix Landmarks Mount de Flavigny Gauls (Vercingetorix)

7. Alesia, 52 BCCasualties & Aftermath Romans: Gauls: >40,000 or 23% 12,000 or 22% The majority of the Gallic tribes immediately bowed down to Roman authority while Vercingetorix was taken to Rome and executed. The few resisting tribes still active were individually hunted down and defeated by Caesar the following year, ending the insurrection. Gaul remained pacified and part of Rome for a thousand years after its final conquest. By Jonathan Webb, 2009

8. The Art of Battle: Animated Battle Maps http://www.theartofbattle.com By Jonathan Webb, 2009