(5) We may now briefly consider the account of this last period of Roman domination which is given in the Epistle of Gildas, _De excidio et conquestu Britanniae_. Gildas, a native of west Britain, wrote in the first half of the sixth century, and his description in cc. 13-20 represents the confused memories of that troubled time, surviving in his own day. As Mommsen[370] says: “haec ut in universum rerum statum in Britannia qui tum fuit recte repraesentare videntur, sic ut narrantur magis famam incertam reddunt quam sinceram rerum gestarum narrationem.” In this account three great devastations are distinguished, and each is attributed to the withdrawal of the Roman garrison. The first was caused by the revolt of Maximus (cc. 13, 14); the island was devastated by Scots and Picts;[371] and it was not until the islanders sent an embassy with letters to Rome that “a legion,” _praeteriti mali_ (the disloyalty of Britain) _immemor_, was sent to Britain, defeated the enemy, and built a wall across the island. The details are of course inaccurate, but the general fact that the rebellion of Maximus brought invasion upon Britain, and after his fall measures were taken (by Stilicho) for fortifying it, is correct. But Gildas conceived that the “legion” when it had done its work did not remain in the island, but returned triumphantly to Rome; and then the old foes began their ravages anew (c. 16). Again an embassy repairs to Rome and begs aid; aid is again given, and the invaders are punished. The soldiers, having given good advice to the timid natives and erected new fortifications, _valedicunt tamquam ultra non reversuri_. Then follows the third devastation, and the famous futile message of the “groans of the Britons” is sent to Aetius. Now this narrative does not correspond to the course of events as we gather it from the scanty contemporary sources, but we can see how it is based on actual occurrences. The third devastation, from A.D. 407, when the army finally departed, to A.D. 446 (the third consulship of Aetius), must represent truly enough the situation of Britain in those years. The circumstance that one legion was withdrawn in A.D. 402, and that the rest departed five years later, in A.D. 407, may have been the historical motive for distinguishing a second period of devastation, which would have to fall before A.D. 407. But a further fact may underlie this tradition of a second devastation. There is no reason to reject the statement in the Irish Annals that King Niall was slain by the Ictian Sea (Sea of Wight), that is, the English Channel, while he was invading Britain, nor is there any reason to question the date assigned to his death, A.D. 405. And if the date is right, even within a year or so, then his last incursion into Britain may be regarded as the historical foundation of the “second devastation” of Gildas.