This Emperor recently went up to the front to make inspection of the Northern defences.
(Well, .... its the kind of thing that's expected of an Emperor ... )
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I must say I found the defences of the
Antonine Wall to be somewhat degraded since their original construction in the 140's A.D. I suppose its not surprising really, but that's certainly not to say that they don't remain impressive.
[Looking North over the Antonine valum, in the outskirts of modern Falkirk]
Indeed, you can still clearly discern the impressive valum and ditch carved into the landscape at many points of the site and which, on the Southern flank, would have supported a major stone, timber and turf wall; reckoned to be palisaded on top and perhaps up to four meters high from ground level.
The Antonine Wall can lay claim to being Rome's most Northerly static frontier; although in almost every other respect, the Antonine is the historically lesser known, less materially intact and altogether, less sexy little sister to the more celebrated Hadrian's Wall (located in Northumbria, England).
[A well preserved stretch of the defences just West of the modern town of Falkirk. The foundation rise - of the now degraded wall - can still be seen on the reverse defencive side]
The Antonine's relative obscurity was dictated by virtue of its limited operational life cycle: c. 140's to 160's AD. Commissioned on the orders of the Emperor Antoninus Pius, the wall runs 37 miles from East to West, right through central Scotland - linking and making good use of the natural obstacles of the major Clyde and Forth estuaries.
[Excavated 'lilia' pits on the advance slope to the Antonine wall. Anti-personnel defences in modern parlance]
Sited only 70 miles to the North of Hadrian's Wall, the Antonine may have represented an attempt to extend Roman rule, or at least military control, into a difficult and rebellious region (Caledonia Major - not Falkirk).
Or it may represent an expression of imperial ego: Antonine seeking as it were, to 'go one better', from his immediate predecessor Hadrian. And of course, one can never rule out an overt imperial attempt to fashion a martial persona; from an Emperor who by all accounts was not an overtly military man.
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Within the imperial context, it was indeed the duty of any Roman Emperor to protect the boundaries of his Empire.
Less obviously - though of critical import - Emperors of Rome were obliged to define themselves as ostensibly 'military' men. Commanders in Chief of the large professionalised and peace-time forces that held down their Empires; preventing unrest and guarding against sovereign incursion.
Form a political perspective, those armies could, paradoxically, be dangerous to imperial rule and it was essential for any Emperor to maintain meaningful connections with the garrison troops of their frontier provinces; if for nothing else, to minimise the risk of rebellion, mutiny and of course militarily backed usurpation. After all, it had not been lost on the historian Tacitus that even by the 1st century AD:
"A well hidden secret of the Principate had been revealed: it was possible, it seemed, for an emperor to be chosen outside Rome."
[Tacitus, Histories, I.5]
The defied Augustus, had dictated a policy of restricted empire expansion and thus static defence. It became therefore not at all uncommon for Emperors - if not actively to campaign - then to at least to make military reviews and expeditions to the provincial and military outreaches of their territories.
Thus by the early Principate had Tiberius, Caligula, Claudius and Nero all established precedents for imperial expeditions of varying scale to the frontiers; visiting the major garrisons and launching regionalised campaigns; providing military, economic or reputational gain.
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For the Antonine Wall, World Heritage Site, see:
http://www.antoninewall.org/
See also:
http://en.wikipedia.org/wiki/Antonine_Wall
and
http://www.historic-scotland.gov.uk/antoninewall