Abstract
Recent excavations at Alchester have shown that this Roman small town in Oxfordshire with its rectangular ground-plan had a military predecessor. It was preceded by one, possibly two, successive vexillation fortresses. Parts are buried deep beneath the civilian occupation layers of the later town. However, west of the late second-century town walls, a significant amount of the earlier vexillation fortress (or a large annexe to such) are more easily accessible to archaeological investigation. This paper focuses on the excavations in 1999, the first ever to take place within the vexillation fortress (or its annexe). The main emphasis is on the military phase. The discoveries from Alchester have major implications for the history of the Roman invasion of Britain. Although the investigations are still in progress and are to continue until 2003, analysis of the mid-first-century finds is well advanced so that there is little doubt about the general historical interpretation.