1. a line of fortifications or earthworks built around a besieged place to prevent escape or relief
Usage: military history; formal
2. the act or process of surrounding or encircling with fortifications
Usage: military history; formal

Examples

• The Roman army constructed a circumvallation around the city to cut off all supply routes.
• The general ordered the circumvallation of the fortress to prevent any reinforcements from arriving.
• Historical accounts describe the circumvallation as a masterpiece of military engineering.
• The enemy attempted to break through the circumvallation but was repelled by defenders.
• Circumvallation was a common tactic used in ancient siege warfare.