Hadrian and the North South Divide
Britain is naturally divided by geography; the south is generally warmer, more fertile, and closer to the continent than the North. Southern England had tin, and could control much of the trade in copper from the Irish Sea, so it was an important component in Prehistoric Northern Europe. The North itself is divided -- Scotland split between a highlands and lowlands.
The realpolitik in ancient times was how to stop those in the north from taking materials from their more prosperous southern neighbours. These North-South dynamics were a recurrent theme of English history and both the North–South divide and Scottish independence are live political issues even today.
In the ancient world, politics was often conducted through warfare, and power was expressed through military engineering. Engineers changed geography and the shape of the landscape; heaped things up and dug things away, build roads, water courses, bridges, towns, and forts. While what remains is stone, but most of the past was formed from earth, straw, and the key engineering component of the ancient world, wood.
It was in wooden ships, built by Celtic shipwrights in Gaul that the Romans, led by Julius Caesar, first arrived in Southern England in 55-54 BC. We know this because in Caesar’s account of his wars in Gaul we get an unprecedented insight into both military engineering and the mechanics of the imperial machine.
I will use the word Celt here even though Caesar made clear he was dealing with the local aristocracy. In this context warfare was interaction between two ruling classes vying for ultimate control of land, its resources, and the people who worked it. ‘Romanization’ was a top down process.
Certainly, there was warfare, but this was driven by diplomacy and a political narrative. The Celtic peoples had long interacted with the Mediterranean world, and in many ways the Roman army was shaped by early unsuccessful encounters with them. For all concerned, warfare was a career and a business opportunity, so everybody knew the rules and what to expect.
While Caesar did not stay, he established the political relationships that got Rome a foothold using the actuality or threat of a Roman intervention to destabilize existing regional politics. Once an area came within range of Rome’s political and military interests, it’s leaders had two choices; cut a deal or fight. All of this on top of the traditional political and military pressures from other rivals beyond Roman control. Invariably, this put the ruling elite between a rock a hard place. For perfectly honorable reasons they might resist and then end up with a worse deal, although not as bad if you make a deal and then broke it. Punitive sanctions went as far as genocide, or you might have gotten away with enslavement.
Once you were a client of the Rome, her army will ensure your security, in return for your assurance that it receive the necessary supplies, principally wheat, but also other material assistance and access to resources. This sort of ‘taxation’ did not need micromanagement -- a treaty was made with the local political authority, so the Romans knew who to blame if obligations were not met. Beyond this, engineering made the Roman army self-sufficient in managing its security.
Rome in the North
When the Romans returned in 43 AD they had controlled the Atlantic Seaboard for ninety years, so Claudius was more properly prepared for a long campaign; not just an army, but a navy also, since control of the sea was key to taking and holding an Island.
When Agricola made the first significant push into the north in the early 80s he had a naval presence on both coasts and even thought about an expedition to Ireland. Then, after the near disaster of the Boudicca revolt, the south was secured, and Rome was on the offensive, initially in the west and then in the North. In a typically aggressive series of campaigns Agricola punched his way north culminating in a battle of Mons Graupius, where his auxiliary troops reportedly killed about a third of a thirty thousand man highlander force.The year was 84 A.D. and it was a high water mark when the highlanders retreated back into their glens in the mountains or the Islands in the West, and reverted to an over the horizon threat. Rather than pursuing them, the Romans chose to construct rough perimeter of timber forts and watch towers blocking off enemy territory. An opportunity and the strategic initiative had been lost due to external decisions and changes in military priorities of the Empire.
At some point towards the end of the first century, the Romans withdrew the majority of their forces from Scotland to the territory of the Brigantes, who controlled Northern England. Their main base was set up at York and occupied by the twentieth legion. The Brigantes had long been loyal to Rome and provided a key buffer state for the Lands to the south. We also presume that some political relations continued with former allies in Scotland, although everything between the campaigns of Agricola and the building of the wall 40 years later is very sketchy.
At this point Hadrian arrives, possibly in response to a revolt in the north involving the Brigantes, who may have been triggered by the death of Trajan. Hadrian brought fresh troops, and re-established a ‘frontier’ in the North of Brigantes territory. After 80 years, the Romans understood that most of what they valued was in the South, so the north was no more than a security zone.
What I have written so far is traditional scholarship, but I wish to change the story that emerges after looking at the ancient engineering.
Hadrian’s North-South Divide
The Wall was a live frontier; so clearly nobody within striking range of the Roman Army was going to be openly hostile, but beyond them were still the people who were isolated. Whatever the political and military circumstances that established the peace, splitting the country in two with a physical barrier probably came as a surprise to those beyond it.
The Roman Army was unlikely to face infantry in mass formation in open battle, and so the main threat probably came from concentrations fast moving mounted troops. A physical barrier forced them to dismount and fight on the Roman terms, against gateways that allowed the Romans to counter attack and outflank their opponents.
Hadrian’s wall is a military engineering solution to the North-South Divide. The line of forts and observation points had proved ineffective, but the Wall changes the geography.
How were the Romans able to spread themselves out across an eighty mile construction project without protection?
In the first season the bulk of the troops were engaged in creating a timber and earth wall with a ditch in front it which protected the work parties behind it. Each of the forts being built was staged with a temporary camp to house the garrison and builders while work was on-going. Similarly, those guarding and building the Wall required accommodations. As part of the process, a construction trench was dug behind the wall for a road -- the spoil neatly piled to allow two wide verges on either side of the planned metalled carriageway. The skilled workers were concentrated in specialist groups working on the Wall starting in the East, while others started work on milecastles and forts. Those digging the trench and laying the foundation were not as skilled as the crews working on the stone wall so their work was completed well ahead of time.
All appears to have gone well at first, but at some point, work appears to have virtually stopped. It is likely that warfare disrupted the construction process. Once the work was restarted again, the quality and quantity of the building was scaled back, the plan to build the road was abandoned, and extra forts were added.
So the wall was built in a war zone, as an army installation and a fortified frontier to contain the threat that had not been eliminated forty years earlier. Whatever the technical and in particular logistic achievements, the Wall did not work, and Hadrian’s successor moved the frontier North to Forth Isthmus, where forces could be concentrated on a shorter frontier.
Little remains of the wall to study, after centuries of robbing, and its systematic demolition by engineers in 1740’s in what turned out to be the final action on the frontier. On 16 April 1746, the Battle of Culloden, probably not that far from Mons Graupius, finally brought the highlands under central control.
There has been very little investigation of the scant traces of that remain of the extensive temporary works or of the builders and forces that guarded them. In the archaeology of these timber and earth structures lies the real key to understanding how the Wall was constructed.