Note 28 — Chapter VI · THE ANGLO-SAXON CONQUEST.
Reading edition
It will be observed that this date is eight years later than that given by Tiro. It is probably derived from Bede (i., 15), who, however, does not seem to have had any definite information as to the exact year of the first invasion, though he certainly places it in the reigns of the Emperors Marcian and Valentinian III., that is (according to his inaccurate reckoning) somewhere between 449 and 455.