Circumvallation and The Roman Military Technology
Circumvallation is regarded as the most popular military tactics of seige which was practiced in the ancient Roman empire as well as in the modern warfare technology. The process involves the attack by an army building a line of fortifications around the besieged city facing towards the city. This line of fortification forms a base to launch the attack against the beseiged city. However in cases where the besieging army is threatened by a field army allied to the city the military strategy over here changes and the besieging army may construct a second line of fortifications between itself and the outside enemy parallel to the lines of circumvallation, known as 'lines of contravallation'. This envelopes the city in a double line of fortifications and doubly protects the besiegers.There are great instances of circumvallation in the military history such as the siege of Alesia, during the Gallic Wars fought by Julius Caesar against the Gauls; siege of Agrigentum, during the First Punic War; battle of Stalingrad, during the Second World War etc. The greatest advantage of the circumvallation and contravallation tactics is that the whole scenario can be easily changed from making it possible to redirect troops from the siege to the defence of the besieging army itself.