History of Julius Caesar Vol. 2 of 2. Napoleon III
wagons and beasts of burden; and, in order to destroy all idea of returning, they burnt their twelve towns, their four hundred hamlets, and all the wheat they could not carry with them. Each furnished himself with meal154 for three months; and after persuading their neighbours, the Rauraci,155 the Tulingi, and the Latobriges,156 to imitate their example and follow them, and having drawn to them those of the Boii who had moved from Noricum to the neighbourhood of the Rhine, they fixed the rendezvous on the banks of the Rhone for the 5th of the Calends of April (the 24th of March, the day of the equinox).157
There were only two roads by which they could leave Helvetia; one crossed the country of the Sequani, the entrance to which was defended by a narrow and difficult defile, situated between the Rhone and the Jura (the Pas-de-l’Ecluse), and where the wagons could with difficulty pass one at a time. As this defile was commanded by a very lofty mountain, a handful of men was sufficient to prevent the access. The other road, less contracted and more easy, crossed the Roman province, after having passed the Rhone, which separated the Allobroges from the Helvetii, from Lake Léman to the Jura. Within this distance the river was fordable in several places.158 At Geneva, the extreme limit of the territory of the Allobroges towards Helvetia, a bridge established a communication between the two countries. The Helvetii decided on taking the most convenient road; they reckoned, moreover, on the co-operation of this neighbouring people, who, but recently subjugated, could have but doubtful sympathies for the Romans.159
Cæsar’s Arrival at Geneva.
II. Cæsar, learning that the Helvetii intended to pass through the Roman province, left Rome hastily in the month of March, hurried by forced marches into Transalpine Gaul, and, according to Plutarch, reached Geneva in eight days.160 As he had in the province only a single legion, he ordered a levy of as many men as possible, and then destroyed the bridge of Geneva. Informed of his arrival, the Helvetii, who were probably not yet all assembled, sent their men of noblest rank to demand a passage through the country of the Allobroges, promising to commit no injury there; they had, they said, no other road to quit their country. Cæsar was inclined to refuse their demand at once, but he called to mind the defeat and death of the Consul L. Cassius; and wishing to obtain time to collect the troops of which he had ordered the levy, he gave them hopes of a favourable reply, and adjourned it to the Ides of April (8th of April). By this delay he gained a fortnight; it was employed in fortifying the left bank of the Rhone, between Lake Léman and the Jura.161 If we estimate at 5,000 men the legion which was in the province, and at 5,000 or 6,000 the number of soldiers of the new levies, we see that Cæsar had at his disposal, to defend the banks of the Rhone, about 10,000 or 11,000 infantry.162
Description of the Retrenchment of the Rhone.
III. The distance from Lake Léman to the Jura, following the sinuosities of the river, is 29½ kilomètres, or 19,000 Roman paces (millia passuum decem novem).163 It is on the space comprised between these two points that a retrenchment was raised which is called in the “Commentaries” murus fossaque. This could not be a continuous work, as the ground to be defended is intersected by rivers and ravines, and the banks of the Rhone are almost everywhere so precipitous that it would have been useless to fortify them. Cæsar, pressed for time, can only have made retrenchments on the weakest points of the line where the passage of the river was easy; indeed, this is what Dio Cassius tells us.164 The labours of the Romans were only supplementary, on certain points, to the formidable natural obstacles which the Rhone presents in the greater part of its course. The only places where an attempt could be made to pass it, because the heights there sink towards the banks of the river into practicable declivities, are situated opposite the modern villages of Russin, Cartigny, Avully, Chancy, and Cologny. In these places they cut the upper part of the slope into a perpendicular, and afterwards hollowed a trench, the scarp of which thus gained an elevation of sixteen feet. These works, by uniting the escarpments of the Rhone, formed, from Geneva to the Jura, a continuous line, which presented an impassable barrier. Behind and along this line, at certain distances, posts and closed redoubts rendered it impregnable. (See Plate 3.)165
This retrenchment, which required only from two to three days’ labour, was completed when the deputies returned, at the time appointed, to hear Cæsar’s reply. He flatly refused the passage, declaring that he would oppose it with all his means.
Meanwhile the Helvetii, and the people who took part in their enterprise, had assembled on the right bank of the Rhone. When they learnt that they must renounce the hope of quitting their country without opposition, they resolved to open themselves a passage by force. Several times – sometimes by day, and sometimes by night – they crossed the Rhone, some by fording, others with the aid of boats joined together, or of a great number of rafts of timber, and attempted to carry the heights, but, arrested by the strength of the retrenchment (operis munitione), and by the efforts and missiles of the soldiers who hastened to the threatened points (concursu et telis), they abandoned the attack.166
The Helvetii begin their March towards the Saône. Cæsar unites his Troops.
IV. The only road which now remained was that which lay across the country of the Sequani (the Pas-de-l’Ecluse); but this narrow defile could not be passed without the consent of its inhabitants. The Helvetii charged the Æduan Dumnorix, the son-in-law of Orgetorix, to solicit it for them. High in credit among the Sequani, Dumnorix obtained it; and the two peoples entered into an engagement, one to leave the passage free, the other to commit no disorder; and, as pledges of their convention, they exchanged hostages.167
When Cæsar learned that the Helvetii were preparing to pass through the lands of the Sequani and the Ædui on their way to the Santones, he resolved to oppose them, unwilling to suffer the establishment of warlike and hostile men in a fertile and open country, neighbouring upon that of the Tolosates, which made part of the Roman province.168
But, as he had not at hand sufficient forces, he resolved on uniting all the troops he could dispose of in his vast command. He entrusts, therefore, the care of the retrenchments on the Rhone to his lieutenant T. Labienus, hastens into Italy by forced marches, raises there in great haste two legions (the 11th and 12th), brings from Aquileia, a town of Illyria,169 the three legions which were there in winter quarters (the 7th, 8th, and 9th), and, at the head of his army, takes across the Alps (see Plate 4) the shortest road to Transalpine Gaul.170 The Centrones, the Graioceli, and the Caturiges (see page 24, note), posted on the heights,171 attempt to bar his road; but he overthrows them in several engagements, and from Ocelum (Usseau),172 the extreme point of the Cisalpine, reaches in seven days the territory of the Vocontii, making thus about twenty-five kilomètres a day. He next penetrates into the country of the Allobroges, then into that of the Segusiavi, who bordered on the Roman province beyond the Rhone.173
These operations took two months;174 the same time had been employed by the Helvetii in negotiating the conditions of their passage through the country of the Sequani, moving from the Rhone to the Saône, and beginning to pass the latter river. They had passed the Pas-de-l’Ecluse, followed the right bank of the Rhone as far as Culoz, then turned to the east through Virieu-le-Grand, Tenay, and Saint-Rambert, and, thence crossing the plains of Ambérieux, the river Ain, and the vast plateau of the Dombes,
154
“Molita cibaria.” (
155
Inhabitants of the country of Bâle. The Rauraci inhabited the diocese of Bâle, which was called
156
Inhabitants of the south of the Grand Duchy of Baden. The town of Stulingen, near Schaffhausen, is believed to derive its name from the Tulingi.
157
158
The bed of the Rhone has changed at several points since the time of Cæsar; at present, according to the report of those who live on its banks, there are no fords except between Russin, on the right bank, and the mill of Vert, on the left bank. (
159
160
Plutarch,
161
This part of the Jura on the left bank of the Rhone is called the
162
163
M. Queypo, in his learned work on the weights and measures of the ancients, assigns to the Roman foot, subdivided into twelve inches, a length of 0·29630m. The Roman pace was five feet, so that the mile was equivalent to a length of 1481·50m.
164
Dio Cassius says that “Cæsar fortified with retrenchments and walls the most important points.” (XXXVIII. 31.)
165
The retrenchments which Cæsar calls
Considered in its
1. From Geneva to the confluence of the Arve and the Rhone, an extent of 1½ kilomètres. Breadth of the river, 90 to 100 mètres. – The left bank is flat in the whole of this extent. The right bank has escarpments almost vertical, the height of which varies from 15 to 35 mètres. (
2. From the Arve to the plateau of Aire-la-Ville, extent 12½ kilomètres. – After leaving the confluence of the Arve, the heights of the right bank of the Rhone increase in elevation; the escarpments become formidable. – The left bank is bordered with similar escarpments, and the river runs thus between high and abrupt banks, everywhere impassable. It preserves this character to a kilomètre above the ravine of Avril, near Peney. The profiles
3. From the plateau of Aire-la-Ville to the point of Epeisses, extent 6 kilomètres. – Down the river from the escarpments of Peney, the heights of the right bank (heights of Russin) form with those of the left bank an immense amphitheatre, nearly circular, the arena of which would be the ground represented green on Plate 3 (diameter, 1½ kilomètres). From the heights of Russin we can descend into the plain to the water of the river. The Rhone, in this part, has never been deep or rapid. The left bank is little elevated, entirely flat opposite the mill of Vert, and the slope of the heights which command it is far from impracticable.
Thus, it was here possible for the Helvetii to effect the passage of the river, and climb the heights of the left bank, if they had not been fortified or guarded. This operation presented least difficulty in the part
An attentive examination of the locality, the discovery of certain irregularities of ground, which we may be allowed to consider as vestiges, lead us to explain in the following manner the expression
Cæsar took advantage of the mean heights at the foot of which the Rhone flows, to cause to be made, on the slope towards the river, and beginning with the crest, a longitudinal trench, of such a depth that the main wall had an elevation of 16 feet. The earth arising from the excavation was thrown down the side of the slope, and the crest was furnished with palisades. (
The hills on the left bank, which rise opposite Russin, are accessible, especially in an extent of 900 mètres, reckoning from the point where the ravine which descends to Aire-la-Ville opens upon the river. They form there, among other peculiarities of the ground, a terrace 8 mètres in breadth, rising from 13 to 14 mètres above the plain, and descending to this by a tolerably uniform
The Romans would be able to prevent the access by means of the trench just described. They, no doubt, continued it to the point
If we continue to descend the Rhone, we meet, on the left bank, first with the perpendicular escarpments of Cartigny, which are 70 or 80 mètres in height, and then abrupt beaches to near Avully. Below Cartigny, the Rhone surrounds a little plain, very slightly inclined towards the river, and presenting a projection of land (
The heights of Avully and Epeisses leave between them and the river a tolerably vast space, composed of two distinct parts. The first is formed of gentle slopes from Avully to a projection of land,
4. From the point of Epeisses to the escarpments of Etournel, extent 6 kilomètres. – From Epeisses to Chancy the Rhone flows in a straight line, and presents the appearance of a vast fosse, 100 mètres wide, the walls of which have an inclination of more than 45 degrees. (
At 200 mètres above Chancy, at
The position of Chancy was certainly the theatre of the most serious attempts on the part of the Helvetii. Encamped on the heights of the right bank, they could easily descend to the Rhone, and there make their preparations for passing, on an extent of 1,500 mètres. The river once crossed, they had only before them, from
The Romans had then to bar the gap
5. From the escarpments of Etournel to the Pas-de-l’Ecluse, an extent of 6 kilomètres. – At the escarpments of Etournel, the Rhone removes from the heights on the right, and only returns to them towards the hamlet of the Isles, 2 kilomètres farther down. These heights form a vast semi-elliptical amphitheatre, embracing a plain slightly inclined towards the river. It is marked by a green tint on Plate 3. People can descend from all sides and approach the Rhone, the bank of which is flat. Opposite, the left bank presents insurmountable obstacles until below Cologny, at
The Helvetii, established on the heights of Pougny and Colonges, could descend to the Rhone, and cross it between Etournel and the hamlet of Les Isles. The Romans had thus to unite the escarpments which terminate at Cologny with the impracticable slopes of the mountain of Le Vuache. Here again we shall see that they took advantage of the peculiarities of the ground.
At the village of Cologny, the heights form a triangular plateau,
To sum up: the works executed on five principal points, between Geneva and the Jura, represent a total length of about 5,000 mètres, that is, less than the sixth part of the development of the course of the Rhone.
Admitting that Cæsar had at his disposal 10,000 men, we may suppose that he distributed them in the following manner: – 3,000 men on the heights of Avully, his head-quarters; 2,500 at Geneva; 1,000 on the plateau of Aire-la-Ville; 2,000 at Chancy; and 1,500 on the plateau of Cologny. These 10,000 men might be concentrated: in two hours, on the heights between Aire-la-Ville and Cartigny; in three hours, on the heights of Avully; in three hours and a half, on the plateau of Chancy; in three hours and a half, these troops, with the exception of those encamped at Geneva, might be brought together between Cologny and the fort of L’Ecluse. It would require five hours to carry the detachment from Geneva thither.
The detachments mentioned above, with the exception of that of Geneva, were established in what Cæsar calls the
Cæsar could reconnoitre every instant the march and designs of the Helvetii, the heights of the left bank of the Rhone presenting a great number of positions where it was easy to place advantageously posts of observation. Commandant Stoffel has pointed out six, which are marked on Plate 3. As it will be observed, the Helvetii, in crossing the Rhone, could not be disturbed by darts thrown from the top of the retrenchments, for these darts would not carry to the left bank of the river. Now there exists at present, between this bank and the foot of the heights in which these trenches were cut, flat ground of more or less extent. Admitting, then, that the Rhone flowed nineteen centuries ago in the same bed as at the present day, we may ask if the Romans did not construct, in these low parts near the bank, ordinary retrenchments, composed of a fosse and rampart. The excavations undertaken by the Commandant Stoffel have revealed everywhere, in these plains, the existence of ground formed by alluvium, which would lead us to believe that the Rhone once covered them. However, even if at that epoch these little plains had been already uncovered, either wholly or in part, we can hardly suppose that Cæsar would have raised works there, since the heights situated in the rear permitted him, with less labour, to create a more redoubtable defence – that of the trenches opened along the crests. As we see, the obstacle presented to the assailants began only with these trenches, at the top of the slopes.
As to the vestiges which still appear to exist, they may be described as follows. The slopes which the Romans fortified at Chancy, from
We must further mention the projection of land
It is easy to estimate approximately the time which it would have taken Cæsar’s troops to construct the 5,000 mètres of trenches which extended, at separate intervals, from Geneva to the Jura.
Let us consider, to fix our ideas, a ground A D V, inclined at 45 degrees, in which is to be made the trench A B C D. The great wall A B C had 16 Roman feet in elevation: we will suppose that A B was inclined at 5 on 1, and that the small wall D C was 6 feet high.
The amount of rubbish removed would be as follows: – Section A B C D = 64 square feet, or, reducing it into square mètres, A B C D = 5 square mètres 60 centimètres.
The mètre in length of the earth thrown out would give thus 5·60 cubic mètres.
If we consider the facility of labour in the trench, since the earth has only to be thrown down the slope, we shall see that two men can dig three mètres in length of this trench in two days. Therefore, admitting that the 10,000 men at Cæsar’s disposal had only been employed a quarter of the time, from two to three days would have been sufficient for the execution of the complete work.
166
167
168
It has been considered to have been an error of Cæsar to place the Santones in the proximity of the Tolosates: modern researchers have proved that the two peoples were not more than thirty or forty leagues from each other.
169
Several authors have stated wrongly that Cæsar went into Illyria; he informs us himself (
170
We believe, with General de Gœler, from the itinerary marked on the Peutingerian table, that the troops of Cæsar passed by Altinum (
171
“Locis superioribus occupatis.” (
172
There is difference of opinion as to the site of Ocelum. The following remark has been communicated to me by M.E. Celesia, who is preparing a work on ancient Italy:
173
“Segusiavi sunt trans Rhodanum primi.” (
174
Cæsar had deferred his reply till the Ides of April (April the 8th). If it were then decided to bring the legions from Aquileia, the time necessary to bring them would have been as follows:
According to this reckoning, Cæsar required 60 days, reckoning from the moment when he decided on this course, to transport his legions from Aquileia to Lyons; that is to say, if he sent, as is probable, couriers on the 8th of April, the day he refused the passage to the Helvetii, the head of his column arrived at Lyons towards the 7th of June.