Harrison misunderstood his source at this point. Britannia had been divided into four or five provinces as part of the reorganisation of the empire carried out at the end of the 3rd century AD under Diocletian. In the late 360s, according to Ammianus Marcellinus, following concerted attacks on Britain from many directions, `... so completely did he [Count Theodosius] recover a province which had passed into the enemy's hands and restore it to its former condition that, in the words of his report, it had a legitimate governor, and it was henceforth called Valentia, in accordance with the emperor's wish ...', Ammianus Marcellinus III trans. J.C. Rolfe (Loeb, 1952), 134-5. The whereabouts of Valentia is unknown, but it constituted only a part of Britain, not all of it.