Retrenchment is a technical term in

fortification A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ...

, where it is applied to a secondary work or series of works constructed in rear of existing defences to bar the further progress of the enemy who succeeds in breaching or storming these. An example was in the

siege of Port Arthur The siege of Port Arthur ( ja, 旅順攻囲戦, ''Ryojun Kōisen''; russian: link=no, Оборона Порт-Артура, ''Oborona Port-Artura'', August 1, 1904 – January 2, 1905) was the longest and most violent land battle of the Russ ...

in 1904. A retrenchment can also be referred to as an '' entrenchment''.

References

{{Fortifications Fortification (architectural elements) Fortification (obstacles)