Contravallation

In fortification, is an intrenchment formed in the same manner as the line of circumvallation, to defend the besiegers against the enterprises of the garrison. An army forming a siege lies between the line of circumvallation and contravallation. The trench of this line is towards the town, at the foot of the parapet, and is never made but when the garrison is numerous enough to hara 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, its parapet is not made so thick, nor the ditch so wide and deep.