Bede's Ecclesiastical History of England, ed. by A.M. Sellar, [1907], at sacred-texts.com
In the year of Rome 798, Claudius, fourth emperor from Augustus, being desirous to approve himself a prince beneficial to the republic, and eagerly bent upon war and conquest on every side, undertook an expedition into Britain, which as it appeared, was roused to rebellion by the refusal of the Romans to give up certain deserters. No one before or after Julius Caesar had dared to land upon the island. Claudius crossed over to it, and within a very few days, without any fighting or bloodshed, the greater part of the island was surrendered into his hands. He also added to the Roman empire the Orcades, which lie in the ocean beyond Britain, and, returning to Rome in the sixth month after his departure, he gave his son the title of Britannicus. This war he concluded in the fourth year of his reign, which is the forty-sixth from the Incarnation of our Lord. In which year there came to pass a most grievous famine in Syria, which is recorded in the Acts of the Apostles to have been foretold by the prophet Agabus.
Vespasian, who was emperor after Nero, being sent into Britain by the same Claudius, brought also under the Roman dominion the Isle of Wight, which is close to Britain on the south, and is about thirty miles in length from east to west, and twelve from north to south; being six miles distant from the southern coast of Britain at the east end, and three at the west. Nero, succeeding Claudius in the empire, undertook no wars at all; and, therefore, among countless other disasters brought by him upon the Roman state, he almost lost Britain; for in his time two most notable towns were there taken and destroyed.