In AD 43, the legion most likely participated in the Roman invasion of Britain led by the emperor Claudius and general Aulus Plautius, because they soon appear amongst the provincial garrison. In AD 50, the Ninth was one of two legions that defeated the forces of Caratacus at Caer Caradoc. Around the same year, the legion constructed a fort, Lindum Colonia, at Lincoln. Under the command of Caesius Nasica they put down the first revolt of Venutius between 52 and 57.