The invasion of Britain, which was carried out by four legions plus auxiliaries under A. Plautius some time in the high summer of A.D. 43, and the subsequent sixteen-day expedition made by the emperor, Claudius, in person in the autumn of that year, form together one of the most famous, if not one of the best understood, episodes in the history of the Roman Empire. In spite of the apparent familiarity of the event our knowledge of the way in which the invasion was planned, and of the route followed, is scanty in the extreme. It is based in part on a very brief summary of Claudius' own journey to Britain, which was a separate expedition of reinforcement, undertaken in order to associate Claudius personally with the prestige of the project. This is described by Suetonius in his Divus Claudius, written some eighty years after the event, but the chief source for the whole invasion is the narrative in Greek given by the historian Cassius Dio some century and a half after the expedition. To these can be added short references of a mere sentence in length, also in Suetonius' Caesares. They relate to the presence of the future emperor, Galba, in Claudius' entourage in Gaul, and to the large part played by Vespasian, and his brother and son, in the early stages of the Roman conquest. Another, and earlier, mention of Vespasian's part in the conquest is to be found in Josephus' Bellum Judaicum, but it contributes no useful or circumstantial detail, and indeed nothing but praise of Josephus' patrons, the Flavian dynasty. Later Roman historians, such as Aurelius Victor and the anonymous writer of De Caesaribus, merely give abbreviated versions of the already meagre information retailed by the historians of the second and early third centuries. Eutropius does add some circumstantial detail, namely that Gn. Sentius (Saturninus) was jointly in command of the expedition with A. Plautius, and that the Orkney Islands (Orcades) were received under Roman control by Claudius. This submission, if it is historical, must have been received through envoys at very long distance, while Claudius was in Colchester. This latter item is repeated by the early fifth-century Christian writer, Orosius.