24 January, 2012

Hadrian’s First Wall Part 3 of 3

On Tyneside, between Hadrian’s Wall and the Ditch to the north, archaeologists have found three lines of double postholes, which, it is argued, represent an early Timber Wall, that along with the Ditch, formed part of a temporary frontier while Hadrian’s Wall was being built. Further, it is argued that the Turf Wall represents the continuation of this structure in the western sector of the Wall. In addition, when the engineering and layout of the Vallum is examined, it appears to be an unfinished road, probably abandoned when warfare interrupted work on the Wall. These insights into the archaeology of Roman military engineering are the key to a new understanding how and why Hadrian’s Wall was built.

An updated summary of a series of articles from this site on the timber and earth structures predating Hadrian’s stone Wall.

Presented in three parts:

3. The Construction of the First Wall
3. The construction of the first Wall
The word ‘step’ is used rather than ‘phase’, because what is being described was one aspect of a more complex process

It is clear that, in accordance with normal logistical principles, the longest, more complex tasks, in particular those requiring the most skilled labour, were prioritised. In terms of the stonework, this was the milecastles. Thus, once construction of the Wall proper begins, things get quite complicated, with separate construction gangs working simultaneously on different aspects of the project.
We also have to be aware that there are forts to build, and all manner of sundry logistical tasks, not to mention the day-to-day garrisoning and guarding of the frontier. However, it is possible to see logical steps in any major project of military engineering, and where the evidence is available, these are confirmed by the archaeology.
Establishing the linear frontier
Step 1 Plan/survey/lay out route 
Step 2 Clear route and establish construction track [Military Way] 
Step 3 Build temporary timber and turf walls Step 4 Dig ditch
Main construction phase [working from East to West, and not completed]
Step 5 Dig Vallum trench, dig and build spoil mounds 
Step 6 Dig Broad Wall foundation 
Step 7 Build Broad Wall 
[Step 8 Dismantle Timber Wall]
Dislocation: Warfare disrupts the process, perhaps more than once.

Vallum Road abandoned and in places backfilled;

Wall completed as Narrow Wall.

Construction sequence - key points
  • The presence of the temporary Wall explains why the majority of the spoil from the ditch was thrown north, with only a small glacis bank to the south.
  • The Vallum was completed [Step 5], while foundation trench for the Wall [Step 6], was not.
  • Digging of a road foundation suggests there was plenty of less-skilled labour available early in the project, and emphasises the importance of a proper road in the overall scheme
The Wall complex looking East at Cawfields

Strategies and tactics

... the Britons are unprotected by armour (?). There are very many cavalry. The cavalry do not use swords nor do the wretched Britons mount in order to throw javelins.'
Vindolanda Tablets [33]
It seems clear that Hadrian’s Wall was a military frontier, conceived in response to a genuine threat, and built by the Roman army with nobody's interests in mind but their own. Cavalry was probably the more immediate threat, certainly to an army planning to spread out along an 80-mile front. Whatever the differences in culture, neither side was politically or militarily naïve, and in an age of hostage-giving and punitive sanctions, which could include genocide, any extant territories near the Roman forces were probably fairly cooperative. This was the first layer of defence, a buffer state, stiffened by outlying forts with good communications to warn of any hostile forces. This gives the option of a pre-emptive strike, before the enemy can concentrate or deploy their forces.
When properly deployed, the Roman army could outfight most enemies, and as a result, it could employ aggressive military tactics, as exemplified by the design of their forts. Unlike a native hill fort or medieval castle, the Roman fort has four, or more, entrances. This allows that an attack on one gate can be counter-attacked and outflanked by the defenders using the other gates. In cavalry forts it is particularly important for the forces to have more than one option to deploy, and to not become trapped inside. Wall forts like Chesters and Birdoswald were designed so three of their four gates opened to the north of the Wall. The overall structure of the Wall seems to reflect a similar strategy, with a surprising number of milecastles and gates, some, like MC39, [right] opening onto almost sheer drops. This makes gates the obvious place to attack, break through, and deploy behind the defenders. However, if the attacker fails to breach the defences, they risk being outflanked by a counter attack and trapped against the Wall.

Conclusions: elephants in the room
After over a century of scholarship, excavations, and surveys, there still remained one central, but subtle, conundrum: if you needed a continuous fortified frontier, and given it would only be effective once it was finished, how come it took about 10 years to complete?
Since there is now little doubt that this was a war zone, breaking your army into small work details and spreading them along a 120km front could be regarded as tactically unwise, if not reckless. Undertaking such a massive construction project might imply that the frontier was peaceful and secure, which tends to undermine the perceived motivation behind building the Wall.
The construction of a temporary Wall solves this problem, securing the frontier against infiltration in the first season. The Timber wall built in the East provides a context and explanation for the Turf Wall, this being the form of the temporary rampart in the west.
Similarly, the various explanations put forward to explain the Vallum have also required a degree of special pleading; to say it is a boundary is to overlook the fact that this is not how Romans, or anyone else, ever built boundaries.[3] It is, however, how they built roads, and this seems to be the only explanation that fits the observable facts of the archaeology. This makes sense as part of the initial plan for the frontier. It makes sense, as does the abandonment of the project as the Wall was scaled back following a ‘dislocation’. This is a key to understanding; the dislocation[s] mark a distinct break in the Wall’s construction, and it is now thought that this was disrupted by serious warfare, perhaps on more than one occasion. When work resumes, the plans for the wall are scaled back. The ‘Broad’ Wall under construction is superseded by a ‘Narrow’ Wall, and there is a marked lowering of standards in the quality of the stonework.[16]
As primarily an army of heavy infantry, the Romans used earth and timber ramparts to protect themselves, particularly from cavalry. Fixed installations ensure the enemy dismounts and fights on terms and ground chosen to suit the defenders. The initial and temporary rampart represented by the Timber and Turf Walls provides a rational and secure basis for the much more complex and specialised task of building the Stone Wall. We can assume on the basis of the Turf Wall that it had some form of turrets and milecastles, and that therefore it was fully garrisoned and in every way fit for its purpose.
While the context of Caesar’s siege of Alésia was quite different, he claims that the first 18km of defences were built in 3 weeks. Thus, it might take about 20 weeks using Caesar's army to build a 117 km long rampart -- but of course it’s not that simple. However, the Roman army was good at this sort of thing, it’s what they did for a living, and creating a 117 km corridor was probably achievable within a year, especially since, with static defensive structures, it’s all or nothing. You can’t have gaps.
The rapid building of a fully functional frontier, probably within a year, was a strategic fait accompli that would have materially affected the military and political situation in the North of Britain. The arrangements and treaties that had ended the prior conflict, and prompted the building of a permanent frontier, may have been undermined by this unprecedented, and probably unexpected, move.
We cannot know if the appearance of this initial rampart was a causal factor in the warfare represented in the dislocation[s] in the construction, but its outbreak indicates that this cautionary approach was justified. Similarly, the building of additional forts along the Wall, when work resumed, also suggests that it had proved ineffective, emphasising the very real threat posed by incursion from the north. While the scaling down of the size of the Wall could be regarded as an attempt to finish it quickly, the decline in the quality of the masonry may also indicate serious casualties among the skilled legionary workforce.
Hadrian’s Wall was soon replaced by the Antonine Wall, which suggests it wasn't a great strategic success. However, the building of Hadrian’s frontier was an extraordinary achievement, not least because in its initial form it was probably built in less than a year. In addition, the growing realisation that this period was punctuated by serious warfare emphasises both the difficulty of the task, as well as why it was felt necessary in the first place.

“... under the rule of your grandfather Hadrian what a number of soldiers were killed by the Jews, what a number by the Britons”

Marcus Cornelius Fronto, letter to Marcus Aurelius, AD162

Bibliography and sources
[Hadrian’s First Wall]
[1] Bidwell, P T, 2005 'The system of obstacles on Hadrian's Wall; their extent, date and purpose', Arbeia J, 8, 53-76. http://www.arbeiasociety.org.uk/journal.htm
[2] Grey literature: Shields Road, Newcastle, Phase 2b, archaeological excavation. TWM archaeology 10/2006
[3] Caius Julius Caesar "De Bello Gallico" and Other Commentaries English translation by W. A. MacDevitt, introduction by Thomas De Quincey (1915) http://www.gutenberg.org/etext/10657
[4] Bidwell, Paul T.; Watson, Moira. 1989 'A Trial Excavation on Hadrian's Wall at Buddle Street, Wallsend'. Archaeologia Aeliana, 5th ser., 17 (1989), 21-28.
[5] T. Frain, J. McKelvey & P. Bidwell 2005 Excavations and watching brief along the berm of Hadrian’s Wall at Throckley, Newcastle upon Tyne, in 2001-2002. Arbeia J, 8 Grey literature; Throckley, Newcastle upon Tyne, archaeological excavation and watching brief. TWM Archaeology 12/2003
[6] Grey literature: Newcastle, Melbourne Street, Archaeological excavations. Archaeological services, University of Durham. http://csweb.bournemouth.ac.uk/aip/gaz2004/ene.pdf
[8] Cip´pus n. 1. A small, low pillar,square or round, commonly having an inscription, used by the ancients for various purposes, as for indicating the distances of places, for a landmark, for sepulchral inscriptions, etc. Webster's Revised Unabridged Dictionary, published 1913 by C. & G. Merriam Co.
[9] http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Polybius/18*.html#18 [Accessed 25/03/2011],
[10] The Military Institutions of the Romans (De Re Militari) by Flavius Vegetius Renatus, Translated from the Latin by Lieutenant John Clarke, translation published in 1767. Etext version by Mads Brevik (2001)
[11] After Fig 15 p73 Bidwell, P T, 2005 'The system of obstacles on Hadrian's Wall; their extent, date and purpose', Arbeia J, 8, 53-76.
[12] http://www.pitt.edu/~medart/menuglossary/INDEX.HTM
[13] James. 1989, Forester's Companion. Cambridge University Press, ISBN 0631108114
[14] Wilmott, T. 2009. Hadrian's Wall: Archaeological Research by English Heritage 1976-2000. English Heritage, Swindon. After Fig. 217 p109. http://www.dur.ac.uk/resources/archaeological.services/research_training/hadrianswall_research_framework/project_documents/TurfWall.pdf [Accessed 25/03/2011]
[15] see: Welfare, H. (2000). "Causeways, at Milecastles Across the Ditch of Hadrian’s Wall". Archaeologia Aeliana. 5 (28): 13–25. And Welfare, H. 2004. ‘Variation in the form of the ditch, and of its equivalents, on Hadrian’s Wall’. Archaeologia Aeliana, ser 5, 33, 9-24
[16] Hill, P. R. 2006. The construction of Hadrian's Wall. Tempus
[17] see: "Excavations at the Hadrian’s Wall fort of Birdoswald (Banna), Cumbria: 1996–2000," by Tony Wilmott, Hilary Cool and Jerry Evans, in Wilmott, T. [ed]. 2009. Hadrian's Wall: Archaeological Research by English Heritage 1976-2000 http://www.english-heritageshop.org.uk/mall/productpage.cfm/EnglishHeritage/_51324/288647/Hadrian's%20Wall [Accessed 29/11/10]
[18] Breeze, D.J. 2003. "Warfare in Britain and the Building of Hadrian's Wall." Archaeologia Aeliana 32, 13 –16.
[19] The basic archaeology of The Vallum and other aspects of the Wall has been recently reviewed in: Wilmott, T. [ed]. 2009. Hadrian's Wall: Archaeological Research by English Heritage 1976-2000. [Most of the general information about the Vallum used in this article is drawn from the summaries of P72–75 & 131–136 cover, along with that from individual excavation reports] at http://www.english-heritageshop.org.uk/mall/productpage.cfm/EnglishHeritage/_51324/288647/Hadrian's%20Wall [Accessed 29/11/10]
[20] This article uses illustrations based on images from Google Earth: http://www.google.com/earth/index.html [Accessed 29/11/10]
[21] Earlier work on the wall: Hodgson, E. 1897. "Notes on the Excavations on the line of the Roman Wall in Cumberland in 1894 and 1895," Trans Cumberland Westmorland Antiq Archaeol Soc, o ser, 14, 390-407. And Haverfield, F. 1897. "Report of the Cumberland Excavation Committee, 1896," TransCumberland Westmorland Antiq Archaeol Soc, o ser, 14, 413-433
[22] Inscription RIB1550 refers to Governor S. Julius Severus http://www.dur.ac.uk/resources/archaeological.services/research_training/hadrianswall_research_framework/project_documents/Carrawburghrev.pdf [Accessed 29/11/10] http://www.roman-britain.org/places/brocolitia.htm [Accessed 29/11/10]
[23] Tony Wilmott, Hilary Cool, and Jerry Evans. "Excavations at the Hadrian’s Wall fort of Birdoswald (Banna), Cumbria: 1996–2000," in Wilmott, T. [ed]. 2009. Hadrian's Wall: Archaeological Research by English Heritage 1976-2000. After Fig.346, p. 252
[24] White Moss and Limestone Corner after: 1897. Trans Cumberland Westmorland Antiq Archaeol Soc, o ser, 14, Plate I. Others: Wilmott, T. 2009. Hadrian's Wall: Archaeological Research by English Heritage 1976-2000. English Heritage, Swindon. Crosby-on-Eden; fig.233 p126. Appletree: after Fig. 217, p109. Birdoswald: after Fig 350, p 257 [scale is 5m, not 10m]. Black Carts: after fig. 202
[25] Wilmott, T. 2007. The Vallum. http://www.dur.ac.uk/resources/archaeological.services/research_training/hadrianswall_research_framework/project_documents/Vallum.pdf [Accessed 29/11/10]
[26] Frere, S. 1974. Britania. Cardinal Books. P 156–7
[27] Mattingly, D. 2006. An Imperial Possession; Britain in the Roman Empire 54BC--AD409. Penguin: Allen Lane. P 158
[28] This would appear to derive from confusion over the word pavimentum, a term used to describe a concrete floor, such as the base of as mosaic. [Viruvius. De Architectura, lib. VII cap. I.] In early scholarship, e.g.: Roman Roads in Britain by Thomas Codrington. 1903. Published by the Society for Promoting Christian Knowledge, London. http://penelope.uchicago.edu/Thayer/E/Gazetteer/Periods/Roman/Topics/Engineering/roads/Britain/_Texts/CODROM/1*.html [Accessed 29/11/10]
[29] Publius Papinius Statius, c. AD 95. Extract from Via Domitiana Silvae 4.3
[30] After: http://upload.wikimedia.org/wikipedia/en/4/4d/Via_Munita.png Roman Road; Via Munita [from Smith, W. 1875. A Dictionary of Greek and Roman Antiquities. John Murray, London. [Accessed 29/11/10]
[31] Wood, E. S. 1967 Collins Field Guide to Archaeology in Britain. After fig. 7, p132
[32] A full list can be found at http://www.romanbritain.org/epigraphy/rib_hadrianswall.htm [Accessed 29/11/10] See also: http://www.dur.ac.uk/resources/archaeological.services/research_training/hadrianswall_research_framework/project_documents/BuildingRecords.pdfWhich states; “8. Vallum stones. In 1936 five stones were found by the north and south mounds of the Vallum at Denton and a sixth stone was found to the west in 1953. One stone gave the name of an auxiliary unit, cohors I Dacorum, and the other five all seem to have named centurions. The stones, clearly building records for the Vallum, are thin, square slabs, and seven further examples, two with the names of different auxiliary units, have been recognised elsewhere on the Wall.” [Accessed 29/11/10]
[33] http://vindolanda.csad.ox.ac.uk/exhibition/army-2.shtml [Accessed 25/03/2011] Birley, R. 2009 Vindolanda: A Roman Frontier Fort on Hadrian’s Wall. Amberley http://www.amberleybooks.com/shop/article_9781848682108/Vindolanda%3A-A-Roman-Frontier-Fort-on-Hadrian’s-Wall Robin-Birley.html?shop_param= [Accessed 25/03/2011]


dustbubble said...

I like it.
Changes it from a grand and imposing "monument" to a dynamic engineering process attempting to solve some very sharp and pressing real-world problems, and being inconveniently impacted by contemporary "events, dear boy, events".

In much the same way you've done for big ol' timber round thingies.
Demystification, that's the ticket.

Although Mr Nitpicky here thinks you might want to flip the N and S on the cross-sectional figures, else it'll look like a early bid for Scottish Independence .. ?

luckylibbet said...

I like your down to earth discussions of how previous generations solved engineering problems. I thought this article was particularly germane, in that you thought out, proactively, how the Romans would need to react in a hostile territory. Excellent reading! - Heather

Geoff Carter said...

Thanks Heather, very kind you. Engineering is like any 'craft', it has a perfectly rational basis, and solving problems is a defining human characteristic. I always worry when archaeology looks to the irrational for an explanation.

Geoff Carter said...

Thanks Dustbubble - well spotted - I seriously messed up with those drawings, which I have used before!
I have corrected it, thanks again for your help.

dustbubble said...
This comment has been removed by a blog administrator.
Lenka said...

Being inconveniently impacted by contemporary "events, dear boy, events".
Kitchen Countertops Long Island

Jimmy Smith said...

great represented by the Timber and Turf Walls provides a rational and secure basis for the much more complex and specialised task of building the Stone Wall.

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Geoff Carter said...

Thanks Jimmy, You hit the nail on the head, a jobs only as good as the prep work!