Circumvallation is a standard military tactic of siege used in ancient and modern warfare. It describes the process of the attacking army building a line of fortifications around the besieged city facing towards the city (to protect itself from sorties by its defenders and to enhance the blockade). The resulting fortifications are known as 'lines of circumvallation'. Lines of circumvallation generally consist of earth ramparts and entrenchments that encircle the besieged city. The line of circumvallation can be used as a base for launching assaults against the besieged city o ...

Including:

• Circumvallation - Examples of circumvallation in military history

Read more here: » Circumvallation: Encyclopedia - Circumvallation