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Caesar on the Siege of Alesia (1)

Reconstruction of Caesar's fortifications at Alesia, Archéodrome Beaune (France): goads, lilies, gravestones. Photo Jona Lendering.
Roman siege works: in front the goads, then the lilies and grave stones (Archéodrome, Beaune)
Siege of Aesia (52 BCE): one of the most important battles during Caesar's conquest of Gaul. After he had taken the Gallic town, only mopping-up operations remained.

Brief account Caesar's own words

Caesar has described the siege in his Commentaries on the war in Gaul, book 7, chapters 63-90. The translation is by Anne and Peter Wiseman.

When the revolt of the Aedui became known, the war was stepped up. Deputations were sent into every part of the country; they did all they could, using their influence, prestige and money, to win the other tribes over to their cause. They got hold of the hostages I had left in their keeping, and by threatening their lives they intimidated any who were hesitating to join them.

The Aedui asked Vercingetorix to come and arrange with them a joint plan of campaign. He agreed, and they then went on to demand that they should be given the supreme command. This led to an argument, and a general council of the whole, of Gaul was summoned at Bibracte., the online home of Ancient Warfare magazine

Map of northern Gaul. Design Jona Lendering.

Gains gathered there in great numbers from all over the country, and when the matter was put to a general vote, Vercingetorix was confirmed as commander-in-chief by their unanimous decision. Absent from this council were the Remi and the Lingones, who retained their alliance with us. The Treverians did not attend either, because they were too far away and were being harassed by the Germans - which, incidentally, was the reason for their taking no part at all throughout the entire war and sending no help to either side.

The Aedui bitterly resented being denied the leadership. They lamented the change in their situation and regretted having sacrificed my generous friendship. However, they had undertaken to fight and did not now dare to break with the other tribes. Eporedorix and Viridomarus, the two young men who had entertained such high hopes, took orders from Vercingetorix, much against their will. Vercingetorix himself ordered the other tribes to provide hostages, and decided on the day by which this should be done. He ordered the whole force of cavalry, numbering 15,000 men, to assemble quickly at Bibracte.

He said that he would be satisfied with the infantry he had before, because he was not going to tempt fortune by fighting a pitched battle. Since he was strong in cavalry, it would be very easy, he said, to stop the Romans getting supplies of grain and forage, always provided the Gauls themselves would not object to destroying their own grain crops and burning their buildings, they must see that by sacrificing their private property in that way they would be gaining power and freedom for ever.

After making these arrangements he ordered the Aedui and Segusiavi, who live on the frontiers of the Province, to provide 10,000 infantry. [...]

I was aware that the Gauls were superior in cavalry, and that if they blocked all the roads I had no chance of getting reinforcements from the Province or from Italy. I therefore sent across the Rhine to the German tribes I had subdued in previous years, asking them to send cavalry and the light armed infantry who regularly went into battle with them [1]. When these arrived, their own horses were not really suitable, and so I took the horses from my military tribunes, the other Romans of equestrian rank, the re-enlisted veterans, and gave them those to ride.

While this was happening, the enemy assembled their forces, both the troops that had been in the territory of the Arvernians, and the cavalry that had been levied from all over Gaul. Large numbers of their cavalry had already gathered, and I was marching along the edge of the territory of the Lingones to get to that of the Sequani so that I could send help for the Province more easily.

Vercingetorix established his forces in three camps about ten miles away from us. He summoned his cavalry officers to a council of war and told them that their hour of victory had arrived. 'The Romans are leaving Gaul,' he said, 'and fleeing to the Province. That is enough to win our freedom for the moment, but certainly not enough to ensure our peace and security for the future. The Romans will raise a greater army and return to continue the war against us. So we must attack them now, while they are on the march and encumbered by their baggage. The infantry may come to their rescue, but if they are held up doing that, the Romans cannot continue their march. If, as I think is more likely, they abandon the baggage and concentrate on saving themselves, they will be stripped of their necessary supplies and their reputation will have gone as well. You certainly must not feel any uneasiness about the possible reaction of the Roman cavalry. You can be quite sure that not one of them will dare so much as to step outside the column. To give you even more confidence, I shall have all our troops drawn up in front of the camps to strike terror into the enemy.'

The cavalry officers shouted out that they should swear a most solemn oath that anyone who did not ride twice through the Roman marching column should not be allowed to enter his home again, or to see his children, his parents, or his wife. This proposal was approved, and they all took the oath.

Next day they divided their cavalry into three sections; two of these appeared in battle order on our two flanks, while the third began to block the way of our vanguard. When this was reported to me, I divided my cavalry into three sections as well, and ordered them to advance against the enemy.

Fighting broke out simultaneously at every point. Our column halted and the legions formed a hollow square with the baggage inside it. Wherever I saw our men in difficulties or being particularly hard pressed, I ordered infantry detachments to move up and form lines of battle. This was effective in two ways; it slowed down the enemy's pursuit and made our cavalry more confident by assuring them of support.

Eventually the German cavalry gained the top of a ridge on the right, dislodging the enemy, who fled as far as the river where  Vercingetorix had taken up position with his infantry. The Germans pursued the fugitives and killed many of them, and the rest, seeing what had happened and afraid that they would be surrounded, turned and fled. They were slaughtered all over the field. Three Aeduans of the highest rank were taken prisoner and brought to me. They were the cavalry commander Cotus, who had had the dispute with Convictolitavis at the recent election; Cavarillus, who had been put in command of the Aeduan infantry after Litaviccus deserted us; and Eporedorix, who had led the Aeduans in their war with the Sequani, before I arrived in Gaul.

Now that all his cavalry had been routed, Vercingetorix withdrew the forces he had positioned in front of the camps, and began at once to march to Alesia, an oppidum [2] of the Mandubii. He ordered that the baggage should be assembled from the camps at once and brought on after him. I had our baggage moved to a nearby hill, left two legions to guard it, and then followed the enemy for what was left of that day. We killed about 3,000 of their rearguard. The next day we encamped near Alesia.

The Gauls were terrified by the defeat of their cavalry, on which they particularly relied. After making a thorough examination of the position of the town, I encouraged my soldiers to set about the strenuous task of constructing siege works round the place.

Aerial view of Alesia, seen from the east.
Alesia from the east (©!!!)

The actual oppidum of Alesia was on a hill top, its position being so high that it was clearly impregnable except by blockade. At the bottom, the hill was washed by rivers on two sides. In front of the oppidum was a plain about 4½ kilometers long; on all other sides it was closely surrounded by hills about as high as that on which it stood. The Gallic troops had occupied the whole of the eastern slope of the hill below the wall of the oppidum, fortifying their position with a ditch and a two meter wall.

The siege works that we were beginning to build formed a circuit of 18 kilometers. Camps were constructed at strategic points along it, and we built 23 redoubts there as well. Pickets were stationed in these during the daytime to guard against any sudden breakout from the oppidum; at night they were occupied by strong garrisons with sentries on watch.

We had started constructing our siege works, when a cavalry engagement took place on that 4½ kilometer stretch of plain that lay between the hills, as I have described above. There was hard fighting on both sides, and seeing our men in difficulties I sent up the Germans to support them, and drew up the legions in front of their camps to prevent the enemy infantry making any sudden attack. The confidence of our men increased when they knew they had the legions behind them.

The enemy were put to flight, and because there were so many of them they made things difficult for themselves, getting jammed in the narrow gateways. The Germans pursued them fiercely right up to their fortifications, and there was great slaughter. Some of them abandoned their horses and tried to get across the ditch and climb the wall.

I ordered the legions I had drawn up in front of the rampart to move forward a little way. The Gauls inside the fortifications became just as alarmed as the rest. They thought there was going to be an immediate attack on them, and so they shouted out a call to arms. Some, in terror, rushed into the oppidum, and to prevent the camp being left unguarded, Vercingetorix ordered the gates of the oppidum to be closed, After killing many of the fugitives and capturing large numbers of horses, the Germans withdrew.

Vercingetorix decided to send out all his cavalry by night before we could complete our fortifications. As they were leaving he told them that each man should go to his own tribe and summon to the war all fellow tribesmen of military age. He pointed out how much they owed to him, and called on them to have a thought for his safety; he had done so much for the freedom of Gaul, and they should not now hand him over to the enemy to be tortured. He explained that unless they did their utmost, 80,000 picked men would perish with him. He had worked it out that he had barely 30 days' supply of grain, though by rationing it strictly he could hold out a little longer. After giving them these instructions, he sent the cavalry out quietly just before midnight, through a gap in our fortifications.

Then he ordered all the grain to be brought in to him; death would be the punishment for any who disobeyed this order. A large quantity of cattle had been brought in by the Mandubii, and this he distributed individually to his men. Grain was to be doled out in small quantities at a time. All the troops who had been posted outside the oppidum were taken inside. By these means he prepared to wait for reinforcements from Gaul while still carrying on the war.

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They were probably Chatti from modern Hessen. This tribe, which belonged to the Celtic La Tène-culture and was only Germanic in Caesar's definition (everybody east of the Rhine), became Rome's most loyal ally. Many of them were later resettled in the Netherlands, where they became known as the Batavians.

The Roman name for Gallic towns on hill tops.

Brief account Caesar's own words
© Jona Lendering for
Livius.Org, 2001
Revision: 25 May 2008
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