The Roman fort at Ribchester is one of the important strategic centres of Northern Britain (fig. 1), where a Roman road from south to north crossed the river Ribble, while another went eastwards to the legionary fortress at York through the Aire Gap and yet a third ran north-westwards to the Fylde. The Ribble, still tidal as far as Ribchester, may well have been navigable in Roman times as far as the lower crossing by a north-south road at Walton-le-Dale, though nowadays even small ships do not come further up river than Penwortham, three miles away. High fells, in Bowland and Croasdale, lie to north and north-east of the fort, which is itself situated in a deep valley. But the general formation of the neighbouring terrain is in wide sweeps of rolling plateau, suited to cavalry movements. In this respect the position has much in common with Stanwix, Corbridge, Binchester, or Lancaster, where Roman cavalry garrisons lay.
Ribchester does in fact appear to have been garrisoned by cavalry throughout the Roman occupation, and the name of the unit stationed there during the latter half of the period is well attested.