The Irish appear in a new role, that of invaders of Britain, in a panegyric of the emperor Constantius Chlorus, written in A.D. 297. The same document and passage contains the earliest known mention of the Picts by that name. "The Britons," says the panegyric, "even then an uncivilised nation and accustomed to no enemies except the Picts and the Irish [Hiberni], still half-naked, readily yielded to the Roman arms and standards." In my last lecture, I have suggested that the overthrow of the old Ulster kingdom is the explanation of the later prominence of the Picts in eastern Ulster. The sudden emergence of the Picts of Britain as a warlike and aggressive people at the close of the third century is susceptible of a similar explanation. Under the Ulster kingdom, the Picts were subject to the Ulaidh. As the Ulaidh declined in power, the Picts became relatively prominent. So in Britain, before the Roman conquests, the Picts, I suggest, were subject to the Celts. The name Calédones or Calédonii, belonging to the principal people of southern Scotland during the early times of the Roman occupation of Britain, is a Celtic name. It is formed by adding a very usual termination to the Celtic adjective _caledos_, meaning "hard" or "hardy." Calédos was in fairly frequent use as a Celtic personal name. Seven instances are quoted by Holder from inscriptions. It is found in Irish, _e.g._, in the term _caladcholg_, "a hard sword." It is the common Irish word for a landing-place from boats, originally no doubt having been applied to firm ground, as distinguished from swampy ground, on the banks of a river, and in this sense it has passed into Anglo-Irish vocabulary in the form "callow"--the "callows" of the Shannon. That the Calédonii did not belong to the old dark-complexioned population is the testimony of Tacitus, who says: "The reddish hair of the inhabitants of Caledonia and their large limbs indicate a Germanic origin." That this Celtic people at one time held sway in a region afterwards dominated by the Picts is witnessed by the place-name Dunkeld in Perthshire. The older Gaelic name is Dún Cailden, _i.e._, Dunon Caledonon, the stronghold of the Calédones. The Celts, who naturally would have been strongest in Lowland Scotland, were so weakened there, I suggest, by the Roman power, that they could no longer maintain their predominance over the Pictish population of the Highlands, and so, towards the close of the third century, the Picts emerge as new and formidable adversaries of Roman Britain on its northern frontier.