Circumvallation

1. (n.) The act of surrounding with a wall or rampart.

2. (n.) A line of field works made around a besieged place and the besieging army, to protect the camp of the besiegers against the attack of an enemy from without.

Thesaurus Entries

advanced work, balistraria, bank, banquette, barbed-wire entanglement, barbican, barricade, barrier, bartizan, bastion, battlement, breastwork, bulwark, casemate, cheval-de-frise, circumvallation, contravallation, counterscarp, curtain, demibastion, dike, drawbridge, earthwork, enclosure, entanglement, escarp, escarpment, fence, fieldwork, fortalice, fortification, glacis, loophole, lunette, machicolation, mantelet, merlon, mound, outwork, palisade, parados, parapet, portcullis, postern gate, rampart, ravelin, redan, redoubt, sally port, scarp, sconce, stockade, tenaille, vallation, vallum, work