Contravallation

in military art, implies a line formed in the same manner as the line of circumvallation, to defend the besiegers against the enterprises of the garrison: so that the army, forming a siege, lies between the lines of circumvallation and contravallation. The trench of this is towards the town, at the foot of the parapet, and is never made but when the garrison is numerous enough to harra and interrupt the besiegers by sallies. This line is constructed in the rear of the camp, and by the same rule as the line of circumvallation, with this difference, that as it is only intended to resist a body of troops much inferior to a force which might attack the circumvallation, so its parapet is not made so thick, nor the ditch so wide and deep; 6 feet is sufficient for the 1st, and the ditch 8 feet broad, and 5 feet deep. Amongst the ancients this line was very common, but their garrisons were much stronger than ours; for, as the inhabitants of towns were then almost the only soldiers, there were commonly as many troops to defend a place, as there were inhabitants in it. The lines of circumvallation and contravallation are very ancient, examples of them being found in histories of the remotest antiquity. The author of the military history of Louis le Grand pretends however, that Cæsar was the first inventor of them; but it appears from the chevalier de Folard’s treatise on the method of attack and defence of places, used by the ancients, how little foundation there is for this opinion. This author a erts with great probability on his side, that these lines are as ancient as the time in which towns were first surrounded with walls, or, in other words, were fortified.