History of Julius Cæsar, Vol. 2 of 2

by Emperor of the French Napoleon III

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 murum fossamque perducit.

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. (See the profile of the retrenchment.) It was, properly speaking, a fosse, the scarp of which was higher than the counter-scarp.

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 talus of 45 degrees.

The Romans would be able to prevent the access by means of the trench just described. They, no doubt, continued it to the point o, where the terrace ceases, and the heights become impracticable. It would then have been from 800 to 900 mètres long.

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 (v r) from 5 to 6 mètres high, with a talus of less than 45 degrees. The bank being of small elevation, the Helvetii might have landed there. To prevent this, the Romans opened, in the talus which fronted the Rhone, a trench similar to the preceding; it was 250 mètres long.

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, q p; the other part is a plain comprised between this projection of land and the left bank of the river. On the right bank a torrent-like river, the London, debouches into flat ground named La Plaine. The Helvetii might have made their preparations for passing the Rhone there, and directed their efforts towards the western point of La Plaine, in face of the low and flat land comprised between the left bank and the escarpment q p. In this part the left bank is only from 1½ to 2 mètres high. Moreover, the slopes of Avully are not difficult to climb, and therefore the Romans must have sought to bar the passage in this direction. (See the broken profile d e f.) The escarpment q p, from its position and height, is easy to fortify. Its length is 700 mètres; its mean elevation above the plain, 18. It presents to the river a talus of less than 45 degrees. The Romans made in this talus, along the crest, a trench, forming wall and fosse. Its length was 700 mètres.

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. (See the profile g g.)

At 200 mètres above Chancy, at k, the character of the banks changes suddenly. The heights on the right sink towards the river in tolerably gentle slopes, through an extent of 2,300 mètres, reckoning from k to the escarpments of Etournel. Opposite, on the left bank, extends the plateau of Chancy. It presents to the Rhone, from k to z, in a length of 1,400 mètres, an irregular crest, distant from 50 to 60 mètres from the river, and commanding it by about 20 mètres. The side towards the Rhone, from k to z, presents slopes which are very practicable. (See the profile h h.)

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 k to z, slopes which were practicable to debouch on the plateau of Chancy.

The Romans had then to bar the gap k z by joining the impassable escarpments which terminate in k with those which commence at z, and which are also inaccessible. To effect this, they opened from one of these points to the other, in the upper part of the slope at the foot of which the Rhone flows, a longitudinal trench k z, similar to that already spoken of. It was 1,400 mètres in length.