The Collaborative International Dictionary
Contravallation
Contravallation \Con`tra*val*la"tion\, n. [Pref. contra- + vallation: cf. F. contrevallation. Cf. Countervallation.] (Fort.) A trench guarded with a parapet, constructed by besiegers, to secure themselves and check sallies of the besieged.
Wiktionary
contravallation
alt. A fortification built around a sieged target by the besiegers. n. A fortification built around a sieged target by the besiegers.
Usage examples of "contravallation".
In a few Ehn, as we were making our way through a corner of the camp, we would presumably encounter some contravallation, some outer lines or ditches, setup to protect the besiegers against possible attack by an outside, relieving force.
I found this detail, however, the absence of external contravallation, like may others in the past weeks, disturbing.