In AD 74/75 the Second Augustan Legion was moved forward to Caerleon - Isca - during the operations to subdue the Silures. Isca, the most westerly fortress in the Roman Empire, was to continue as the base of legio II for more than 200 years. The importance of Caerleon cannot be overstressed in the opportunities it offers for the study of a legionary fortress. Excavations have been on-going in Caerleon and its environs since 1908. The vast amount of evidence derived from these excavations allows the authors to explore in detail the structural development and history of the fortress, its garrison and the wider community.
The construction of the first fortress, mainly from timber, and the provisioning of its garrison must have had a significant impact on the local environment and population. However, the Second Augustan had many commitments beyond south Wales and there must have been long periods when the fortress would have been maintained by a caretaker garrison only. Indeed, this raises the questions as to why the legion retained its home base at Caerleon when its major area of operation was in northern Britain. Archaeological evidence shows that as early as the late second century, the legion, with detachments serving elsewhere, was depleted on a permanent basis.
By the end of the third century a fortress the size of Caerleon had become redundant. However, despite the undoubted demolition of some buildings from the late second century onwards, there is evidence for continuity of occupation to the late fourth century. Although the indications increasingly point to a continued military presence, the evidence is such that a partial or total civilian presence cannot be precluded. This will be the most detailed account of the structural evolution and character of the fortress since George Boon's Isca published in 1972.