Geophysical survey at Llanfor, near Bala, revealed two temporary camps and a large wooden fort in exceptional detail. The camps are assumed to be evidence of an early Flavian invasion force. The fort, which contained a garrison that probably comprised a complete ala of auxiliary cavalry and a cohort of legionaries, is interpreted as a short-lived campaign base that existed during the transition between invasion and consolidated occupation. Parallels are drawn between Llanfor and similar forts in Britain and Germany.