These raids became at last so intolerable, that the Roman government sent an able general named Theodosius (father of the emperor Theodosius the Great) to Britain to check them. At the very time that Theodosius was in Britain, a brave and strong-handed king reigned in Tara, named Criffan (A.D., 366 to 379), who on several occasions invaded Britain, and took possession of large tracts, so that he is called in our old records “Criffan the Great, king of Ireland, and of Albion to the British Channel.” The Roman historians tell us that Theodosius succeeded in beating back the Picts and Scots, and even chased them out to sea, in which there is probably some exaggeration, as there is, no doubt, on the part of our own historians in calling Criffan “King of Albion to the British Channel.” Criffan was succeeded by Niall of the Nine Hostages (A.D. 379 to 405), who was still more distinguished for foreign conquests than his predecessor. He invaded Britain on a more extensive and formidable scale than had yet been attempted, and swept over a large extent of country, bringing away immense booty and whole crowds of captives, but was at length forced to retreat by the valiant Roman general Stilicho. On this occasion a Roman poet, praising Stilicho, says of him--speaking as Britannia:--“By him was I protected when the Scot [_i.e._, Niall] moved all Ireland against me, and the ocean foamed with their hostile oars.” For the extensive scale of these terrible raids we have the testimony of the best possible authority--St. Patrick--who, in his “Confession,” speaking of the expedition in which he himself was taken captive (probably that led by Niall), says:--“I was about sixteen years of age, when I was brought captive into Ireland _with many thousand persons_.” The preceding were warlike raids; but no doubt, while the main body of the host returned on each occasion to their homes in Ireland, large numbers remained and settled down in Wales. But we have an account of at least one expedition undertaken with the direct object of colonising. In the third century, a powerful tribe called the Desii, who occupied the territory of _Deece_, near Tara, were expelled from the district by King Cormac Mac Art, for a serious breach of law. Part of these went to Munster, and settled in a territory which still bears their name, the barony of Decies, in Waterford. Another part, crossing over to Wales under one of their leaders, took possession of a district called Dyfed, where they settled down and kept themselves distinct as an immigrant tribe, speaking their own language for generations, till at length they were absorbed by the more numerous population around them, just as, many centuries later, the Anglo-Normans who came to Ireland were absorbed by the Irish.