In AD 197, because the Wall garrison had been taken to the continent to contest the Imperial throne, the Roman forts of the north as far as York were sacked and burnt. Long stretches of the Wall were pulled down. The Emperor Severus sent troops and a new governor to Britain; a more aggressive policy than Hadrian's was planned and High Rochester and Risingham in Northumberland were added to the line. No statelier defences were ever erected in Britain than at Risingham, using dressed ashlar from the famous local quarry.

Severus then decided that an Imperial expedition was needed to assert Roman authority over Scotland and, despite being over sixty and having to be carried in a litter because of his gout, came to Britain with his sons , his whole court and a formidable army in AD 208. Severus expanded Corbridge as an important stores-base and in keeping with the Roman practice of supplying their armies from the sea, he had twenty-four new stone granaries built at the fort of Arbeia on the Lawe in South Shields, where twelve of them can be seen today. These are the only permanent stone-built granaries yet found in the whole Roman empire. They had a capacity of 3,500 tonnes and could feed an army of fifty thousand for two months.

Severus pushed north from the Wall, and crossed the Forth-Clyde line intending to conquer the whole island of Britain once and for all. The Roman armies, under the command of Severus' elder son, the future Emperor Caracalla, reached northern Scotland after considerable loss from ambush and winter marching, and the Caledonians ceded a large slice of territory. They rose again as soon as the Romans retired southward but in the grim campaign of AD 210, when the legionaries had orders not just to defeat, but to wipe out the barbarians, the Caledonians were only 'saved by the death of their haughty enemy' as Gibbon puts it. The Emperor Severus had died at York in AD 211 - the last emperor to die in bed for 80 years.

Though the Romans eventually withdrew south of the Forth again, the province was at peace for almost a century, a longer period than at any time before or after. Prosperity and enterprise flourished as the newly-reoccupied country was economically developed. The Redesdale iron field just south of Risingham was vigorously exploited and the ore brought into Corbridge where a military arsenal existed. The lead mines on Alston Moor began to be worked, under the garrison of Whitley Castle.

An inscription to Severus forms part of the roof of the crypt of Hexham Abbey

Later Roman emperors in northern Britain on martial business included Constantius Chlorus, and his son (later Constantine the Great, who was proclaimed at York); Constans; and in AD 368-72, Count Theodosius and his son (later Theodosius the Great).