Matthew_
First Post
Not sure I can do much better than wax lyrical about what I remember of my undergraduate courses, and I think that it might well be mixed up in the "grand strategy of the Roman Empire" discourse [i.e. whether they had one or not]. From what I remember, it used to be thought that Hadrian's Wall (and to a lesser extent the Antonine Wall and the Danube Frontier) were literally barriers expected to protect the Roman territories in a very literal way from the barbarians, much as is depicted in the often unintentionally hilarious King Arthur film, and that the Great Wall of China was pretty much the same sort of thing.
Of course, fortified castles and towns of the ancient and medieval ages did not command avenues of march like their early modern and modern counterparts, lacking as they did artillery, which is one of the chief points R. C. Snail made many years ago in his book Crusader Warfare. The defence "in depth" once envisioned for the Holy Land of fortifications simply did not reflect the reality of the situation, and much the same can be said of the grandiose claims once made about Roman static defences. The relatively modern realisation that medieval warfare was conducted largely through raiding, sieges, and the avoidance of battle contrasts somewhat with the more frequent battles we hear about in the ancient world, but there are still lessons to be learned there.
I am waffling a bit, probably because a lot of this is much vaguer in my memory than I would like to admit! However, what you get with a big wall marking territorial boundaries is much the same as with any other ancient or medieval fortification, which is to say something that a) Makes a huge statement about your power to friend and foe alike, b) Reduces the effectiveness of low scale raiding, cattle rustling and the like, c) Is a barrier to large scale military action, if not insurmountable d) Lets you control to a large extent who passes peacefully back and forth between the divided territories.
The manpower required to defend Hadrian's Wall is said to have been ten to fifteen thousand, which was about 5% of the total under arms (if I remember rightly estimated at 300,000), so a significant number, but realistically capable of defending 70+ miles of wall from a concentrated effort? Maybe, I guess you cannot rule anything out completely, but would it really be more militarily effective than a field army? Hard to countenance, just so much that could go wrong with a static defence, too easy to cut sections off and so on. Militarily, what the wall more likely provided on that scale, with its set back forts and garrisons, was an early warning and informational transferral systems that would allow a field army to be mustered at the right point(s).
But dealing with full scale invasions would be by far the exception, and not at all the day-to-day purpose of the wall. Apart from discouraging and blunting raids and immigration from beyond the wall, it allowed the Romans to control what went from the Roman side to the non-Roman, and vice-versa, and at what cost. Roman coinage flowed from the centre of the empire out to the frontiers where it paid the armies, and then out into the wild where it was too often lost to the civilised world. The profit from trade (and the forts would themselves have operated as trade centres) must have been significant, but control of trade also made it theoretically possible to restrict the sale of Roman munitions to the barbarians. Charlemagne had to rely on the obedience of his subjects measured against their greed for gain when he forbade the sale of Frankish swords to the enemy, but the Romans could more easily and actively restrict the transport of such items (indeed, the military commanders should have been particularly invested in ensuring the barbarians remained militarily inferior in terms of technological scale).
Now, I could well be wrong about all of the above, as I say it has been a long while since I actually studied the subject, but a quick look at the Wikipedia entry for Hadrian's Wall suggests to me that I am probably not too far off the mark in my (certainly by now much altered) recollection. Might be worth looking into the subject further next time I am in the library, if time allows (or I suppose I could browse the internet, or maybe just start a thread or do a search at RomanArmyTalk).
Ha, ha. Yeah, well, I guess if the gate was part of a military outpost (and I can only suppose it must have been) it would be surprising if there was not a brothel in the vicinity!
