The Antonine Wall runs between the Forth and Clyde in Scotland, about 100 miles (160 km) north of Hadrian’s Wall. It was built under the orders of Antoninus Pius in the early 140s, and was permanently abandoned in the 160s. His Roman biographer states that he built a turf wall in Britain once the governor, Lollius Urbicus, had defeated the ‘barbarians’. Pius may have needed to establish a reputation for himself as a firm ruler, but perhaps there were local problems like idle soldiers, the tying up of too many troops in the numerous garrison posts of Hadrian’s Wall, and difficulties with supplying the remote central sector forts. There may even have been a change of policy requiring more exact control of the area north of Hadrian’s Wall, perhaps connected with the fact that the latter cut across the tribal lands of the Brigantes, the principal tribe of northern Britain. The plan may even have been to create a kind of ‘neutral zone’ between the Walls, through which individuals and groups could pass.
The new frontier was only 37 Roman miles (59 km) long, or around half that of Hadrian’s Wall. It was modelled on its predecessor, but was built entirely of turf on a cobble base 14 Roman feet (4.1 m) wide. The new frontier had a forward ditch, about 20 to 30 Roman feet (6 to 9 m) wide, but no equivalent to the Vallum was ever dug. Unlike Hadrian’s Wall, the forts were designed to be part of the new frontier from the beginning, and even preceded the turf curtain in some cases; however, a second wave of forts seem to have been added during construction. The forts were interspersed with fortlets, but there is no positive evidence for a regular series of turrets. Their combined capacity means that the total garrison cannot have been very much less than that on Hadrian’s Wall. In military terms, this supplied twice as many men per mile of frontier than before. It was backed up by the garrisoning of forts in the land between the Walls. At High Rochester, an old Flavian fort site was utilized to create a new stone fort. At Birrens, the Hadrianic fort seems to have remained in occupation, with rebuilding work apparently undertaken by detachments of Rhine legions.
Controlled movement across Hadrian’s Wall is thought to have been abandoned: the milecastle gates were either removed or left open, and crossings were installed on the Vallum (the latter remain the clearest trace of this policy today, but are not easily datable). As far as the forts are concerned, their garrisons were probably transferred to the new Wall. Unfortunately, so few early garrisons on Hadrian’s Wall are known that this is difficult to show, but the First Cohort of Hamian archers, stationed at the Stanegate fort of Carvoran under Hadrian, was posted to Bar Hill on the Antonine Wall for a while before returning to. Even so, it is unlikely that the Hadrian’s Wall forts were abandoned. At Birdoswald there is no discernible gap in datable finds of the second century. However, some parts of the fort, unbuilt on since its construction, remained open; as these included the site of the later granaries, it has been suggested that the fort was only manned by a reduced garrison.
It’s unfortunate that we know so little about the history of later Roman Britain. Most of our detailed historical information dates to the first century, such as the accounts written by Tacitus. Thereafter, historians and archaeologists have no choice but to piece together a chronology from brief literary references to Britain, inscriptions, coins, and archaeology. Even this deteriorates because inscriptions, never common, become even scarcer after the early third century, and literary references increasingly sporadic and more unreliable. So it has proved difficult to avoid making much from little. This is far from unusual in archaeology, even for the Roman period. Britain was a backwater, a testing ground for premier military careers, but otherwise of only secondary importance to the Empire. She became useful and productive, but was always dispensable, making headline news in Rome only when war broke out. This forces a reliance on what is recovered from the ground. There is no avoiding the reality that pottery and coin evidence is far too imprecise, however carefully researched, to provide exact chronologies when historical references and inscriptions are lacking.
In the period 142-4, around the same time as the Antonine Wall was begun, coins were struck depicting Britannia, and were followed by a similar issue (which is normally only found in Britain) for the years 154-5. Such coins were usually produced at times of military success, but they do not always explicitly state this. The geographer Pausanias describes a phase of warfare during Pius’ reign which may have taken place in northern Britain, but he appears to have been mistaken, or had confused two different wars. The arrival of legionary reinforcements at Newcastle from Germany or the return of detachments temporarily sent to Germany, and rebuilding at Birrens, about this time might suggest something was afoot. Destruction and repair on the Antonine Wall may be attributable to these implicit phases of warfare.
But archaeologists have no doubt that the Antonine Wall saw two distinct phases of occupation, following careful examination of two levels of destruction and demolition debris. The problems are when and for how long, and whether the phases ended because of defeat or deliberate withdrawal. These have proved difficult to resolve.
The reoccupation of Hadrian’s Wall
Hadrian’s Wall was recommissioned by the 160s, though repair work is testified by 158. Calpurnius Agricola was sent to govern Britain around 163. He is mentioned by the biographer of Marcus Aurelius, and his name appears on inscriptions at Carvoran and Stanwix. It seems reasonable to assume that the Antonine Wall had, by then, been given up for good. If there was any Turf Wall left in the western sector of Hadrian’s Wall, it was now replaced in stone. Some of the turrets were demolished between this period and c. 220, being reduced to their lower courses, and the Wall restored to full width over them. It is unlikely that the Walls were occupied simultaneously. So, a logical assumption would be that somewhere between the late 150s and early 170s a decision was made to give up the Antonine Wall. The forts to its rear, such as High Rochester, remained in use, showing that withdrawal did not mean that the Roman command regarded the area beyond Hadrian’s Wall as abandoned. The visible fort at South Shields seems to belong to this period, and reinforced control of the lower reaches of the river Tyne to the east of the end of the Wall at Wallsend.
The Roman army retained a precarious hold on northern Britain. Cassius Dio, describing the reign of Commodus (180-92), mentions a war in Britain which he said was the most troublesome of the reign. Damage at some forts, such as Haltonchesters, has been attributed to this event, but only on the loosest circumstantial association. Dio does not specify the Wall (though he makes clear he means just one), so we can only assume that he was referring to Hadrian’s Wall. The tribes were apparently suppressed, because in 184 coins were issued with legends stating explicitly ‘Vict[oria] Brit[annica]’.