You searched for: “circumvallation
circumvallation (s) (noun), circumvallations (pl)
1. A more or less continuous chain of redoubts and breastworks raised by besiegers outside the line of a besieged place to protect the besiegers from attacks from the outside; such as, by a relieving force.
2. A trench guarded with a parapet, constructed by besiegers, to secure themselves and check sallies of the besieged.
This entry is located in the following units: circum- (page 6) vall- + (page 1)