Julius Caesar, De bello Gallico Book V c.13 describes the island of Mona as being midway between Britain and Ireland. He certainly meant Man, which, however, was usually named Manavia in classical sources, which refer to Anglesey as Mona. Ptolemy names both, as Monaeoda and Mona respectively. Tacitus was thus declining to follow Caesar into error when he reported the Roman attack on Anglesey - Mona - in 60 or 61 A.D.