The Severan Tondo, Septimus Severus, Julia Domna, Caracalla and defaced Geta

Bede ;
Ecclesiastical History of the English Nation, Book I;

HOW THE EMPEROR SEVERUS DIVIDED THAT PART OF BRITAIN, WHICH HE SUBDUED, FROM THE REST BY A RAMPART

IN the year of our Lord 189, Severus, an African, born at Leptis, in the province of Tripolis, received the imperial purple. He was the Seventeenth from Augustus, and reigned seventeen years. Being naturally stern, and engaged in many wars, he governed the state vigorously, but with much trouble. Having been victorious in all the grievous civil wars which happened in his time, he was drawn into Britain by the revolt of almost all the confederate tribes; and, after many great and dangerous battles, he thought fit to divide that part of the island, which he had recovered from the other unconquered nations, not with a wall, as some imagine, but with a rampart. For a wall is made of stones, but a rampart, with which camps are fortified to repel the assaults of enemies, is made of sods, cut out of the earth, and raised above the ground all round like a wall, having in front of it the ditch whence the sods were taken, and strong stakes of wood fixed upon its top. Thus Severus drew a great ditch and strong rampart, fortified with several towers, from sea to sea; and was afterwards taken sick and died at York, leaving two sons, Bassianus and Geta; of whom Geta died, adjudged a public enemy; but Bassianus, having taken the surname of Antoninus, obtained the empire.

Archaeological evidence shows that Alfenus had been rebuilding the defences of Hadrian's Wall and the forts beyond it, and Severus' arrival in Britain prompted the enemy tribes to immediately sue for peace. The emperor had not come all that way to leave without a victory however, and it is likely that he wished to provide his teenage sons Caracalla and Geta with first hand experience of controlling a hostile barbarian land.

An expedition led by Severus and probably numbering around 20,000 troops moved north in 208 or 209, crossing the wall and passing through eastern Scotland in a route similar to that used by Agricola. Harried by punishing guerrilla raids by the northern tribes and slowed by an unforgiving terrain, Severus was unable to meet the Caledonians on a battlefield. The emperor's forces pushed northwards as far as the River Tay, but little appears to have been achieved by the invasion, as peace treaties were signed with the Caledonians. By 210, Severus had returned to York with the frontier set at Hadrian's Wall and assumed the title Britannicus. The title would mean little with regard to the unconquered north, which (with Rome's power still stopping at the Wall) clearly remained outwith the authority of the Empire. And almost immediately another northern tribe, the Maeatae, again went to war. Caracella left with a punitive expedition, but by the next year his ailing father had died and he and his brother left the province to press their claim for the throne.

As one of his last acts, Septimius Severus tried to solve the problem of powerful and rebellious governors in Britain by dividing the existing province into Upper Britain and Lower Britain. Although this kept the potential for rebellion in check for almost a century, it was not permanent. Historical sources provide little information on the following decades, a period often called the Long Peace.