[Sidenote: A.D. 204. Division of Roman Britain into two Provinces.] The great extent of the province, and the difficulty experienced in defending it, probably led to Roman Britain being now divided into two provinces. Herodian distinctly tells us that after the war with Albinus, Severus settled matters in Britain, dividing it into two governments, and Dio alludes to them under the names of Upper and Lower Britain. It is impossible now to ascertain the precise relative position of the two provinces; but the older province of Britain, formed in the reign of Claudius, seems to have been one, while the other probably embraced the later conquests of the Romans from the Humber to the Firths of Forth and Clyde, comprising mainly the great nation of the Brigantes with its dependent tribes. Dio states that the second and twentieth legions were stationed in Upper Britain, while Ptolemy places the one at Isca Silurum or Caerleon; and both Ptolemy and the Itinerary of Antonine place the other at Deva, now Chester. The sixth legion was stationed, according to Dio, in Lower Britain, and Ptolemy as well as the Itinerary of Antonine place it at York, which is the only indication we have of the situation of the two provinces. These few meagre and incidental notices are all that we possess of the state of the Roman occupation of Britain, from the clear and detailed account given by Tacitus of Agricola’s campaigns, to the second great attempt to subdue the northern tribes, which we are now approaching. The one great feature of this intermediate period was the construction of the great rampart between the Firths of Forth and Clyde, and the fixing of that boundary as the frontier of the province—the line of separation between the provincial Britons and the barbarian or independent tribes. To the few emphatic words of the historian of Antoninus, the remains of the great work itself, and the inscriptions found in its vicinity, add confirmation and a definite locality; and the great boundary at the Firths of Forth and Clyde became from thenceforth the recognised and permanent frontier of the Roman province. [Sidenote: A.D. 208. Campaign of the Emperor Severus in Britain.]