When a Roman encampment was reinforced by strengthening the ramparts with a wooden stockade or stone wall, it became more than just a temporary defence works, it became what is known as a `castra stativa'. The castra stativa served as a base from which actions could be launched into the surrounding area, and if necessary a place to fall back to if things did not go well. More elaborate castra stativa were provided with castellas or watch towers, which were used to flank the gates and at the corners and at regular intervals along the vallum. There were two types of castra stativa |