the confederated tribes, and after many great and severe battles, he thought fit to divide that part of the island that he recovered from the other unconquered nations, not with a wall as some have imagined but with a rampart, for a wall is made of stones. A rampart for which camps are fortified to repel enemies is made of sods cut out of the ground and raised high above the ground like a wall, having in front of it a trench from whence the sods were taken, with strong stakes of wood afitted above it. Thus Severus drew a great trench and rampart fortified with several towers from sea to sea, and there at York afterwards he fell sick and died." Asser (9th century), writing in The Life of King Alfred: "The wall was a good defence as long as Roman soldiers remained to guard it. But in process of time – about two centuries after Severus's day – the Roman empire itself began to decline, even in the very seat and centre of its power; and then, to preserve their own capital from destruction, the government were obliged to call their distant armies home." Nennius, Historia Brittonum ("History of the Britons", 9th century), Chapter 23: "Severus was the third emperor who passed the sea to Britain, where, to protect the provinces recovered from barbaric incursions, he ordered a wall and rampart to be made between the Britons, the Scots, and the Picts, extending across the island from sea to sea, in length one hundred and thirty-three miles: and it is called in the British language Gwal. (*) Moreover, he ordered it to be made between the Britons, and the Picts, and Scots; for the Scots from the west, and the Picts from the north, unanimously made war against the Britons; but were at peace among themselves. Not long after Severus dies in Britain." (*) Or "the wall". One manuscript here adds: "The above-mentioned Severus constructed it of rude workmanship in length 132 miles; i.e. from Penguaul, which village is called in Scottish Cenail, in English Penteltun, to the mouth of the river Cluth and Cairpentaloch, where this wall terminates; but it was of no avail. The emperor Carausius afterwards rebuilt it, and fortified it with seven castles between the two mouths: he built also a round house of polished stones on the banks of the river Carun (Carron):