a more or less continuous chain of redoubts and breastworks raised by besiegers outside the line of circumvallation of a besieged place to protect the besiegers from attacks from the outside, as by a relieving force.
Origin: 1670–80; contra-1 + vallation; cf. F contrevallation, It contravvallazione
[kon-truh-vuh-ley-shuh
n] 