Crenellations and the Castra Praetoria

[mcbishop]

Here's something to start a good debate ;-)

One of the only early imperial military bases with its curtain wall surviving from the base to the top of its merlon caps (at least on one side) is the Castra Praetoria in Rome. The north wall is a palimpsest, with later defences being plonked directly on top of the earlier, thus embedding the old defences within the later. Here is the CP looking towards the north wall:



Richmond (before he was sent packing from Rome by the fascists) wrote a very famous article about the relationship of the CP to the Aurelian Walls in which he said of the Tiberian defences:

Level with an external quadruple string-course was the rampart-walk... Then came a low breastwork, provided with a coping and small battlements at every twelve feet, slightly set back on the coping and capped with big tiles. (Richmond 1927, 14)*

and here you can see what he is referring to:



When I first saw this up close and 'in the opus latericium' (so to speak) I saw something else. The string course is very obvious, but Richmond's interpretation of the battlements was doubtless influenced by a common classical tendency to show crenellations as widely spaced (you can see this on Trajan's Column and on a mosaic from Fishbourne but to me setting the merlons back from the face of the curtain wall made no sense. They also seem to be made of larger bricks than the rest of the curtain wall. What I saw instead were broad merlons with small gaps (which, defensively, make more sense as they offer more protection). You could even see that the base of each opening had been given a broad brick sill, presumably to prevent weathering of the underlying brick-faced concrete (and we must assume the merlons would be capped in a similar way - indeed, there are hints of this in places) and which, if they formed the base of a narrow merlon, would surely make it unstable if they passed all the way through.

However, every time you look at the walls you see something different (partly influenced by the different colourations of the bricks), to the point where I don't think you can really argue conclusively one way or the other, just allow for both possibilities.

I have posted more piccies of the CP (including the wonderful embedded porta principalis dextra) but our Italian colleagues (or indeed any RAT members who happen to be visiting Rome) may care to wander along to the Viale del Policlinico and puzzle it out for themselves.

So, broad merlons or narrow ones, what do you reckon?

Mike Bishop

*I.A. Richmond, 'The relation of the Praetorian Camp to Aurelian's Wall of Rome', PBSR 10, 1927, 12-22

[Tarbicus]

This might be of use if, like me, you don't know your crenellations from your merlons :wink:

http://architecture.about.com/library/b ... lement.htm

http://www.thefreedictionary.com/_/view ... e=A4battmt

[sulla felix]

Ave Tarbicus,

Merlons were indeed proving a problem for me. Laudes to you for the very useful link.

[sulla felix]

Mike,

Looking at the photo above, could there be a case for no crenellations at all from the earlier phase of construction. The colouration of the bricks above the stringing courses (battlement floor level?) is different from the colouration of the bricks forming the battlement itself. I have looked at the other pictures but they do not really help. How necessary would crenellations have been during the Tiberian period for what was effectively a barracks for the Praetorian Guard? Just a thought.

If, in the alternative, there were indeed crenellations upon the original structure I tend towards broad merlons. :?

[sulla felix]

Just to make this clearer I have indicated what I mean on the photo with some rudimentary annotation (just a beginner at this tech stuff).



You can aslo see that the quality of the bricks (material) and brick laying (workmanship) are very different. The perps in the bricks (vertical joints) are not as well staggered as the brickwork below.

I have managed to convince myself of this - anyone else?

[Tarbicus]

Mike, is this what you mean?

But Barry has a point about the bricks.

[mcbishop]

You can aslo see that the quality of the bricks (material) and brick laying (workmanship) are very different. The perps in the bricks (vertical joints) are not as well staggered as the brickwork below.

Problem is we could be looking at differences between work gangs rather than phasing. There are indeed three different zones: one up to the string course, a different, but similarly red, one above that, which comprises the breastwork; then a yellow one which may be either a) broad merlons or b) late infilling between the narrow set-back and slightly darker merlons. It is quite clear that the Romans not only built in horizontal stints (like Hadrian's Wall, divided between centuries, each doing a few paces length) but also vertically (one gang doing the foundation of the wall, the next the main body, and so on; Peter Hill's recent book on the construction of Hadrian's Wall makes this quite clear). Add to that the problem of brick supply (were they stockpiled beforehand or did they have kilns churning them out as they built it on a just-in-time supply system, which would mean that different firings might be slightly different colours?).

Interesting conundrum!

Mike Bishop

[mcbishop]

Mike, is this what you mean?

I bet you were using Photoshop in your cradle! Yes, precisely that.

But Barry has a point about the bricks.

See my comments above. Work gangs could explain it.

Mike Bishop

[sulla felix]

Problem is we could be looking at differences between work gangs rather than phasing. There are indeed three different zones: one up to the string course, a different, but similarly red, one above that, which comprises the breastwork; then a yellow one which may be either a) broad merlons or b) late infilling between the narrow set-back and slightly darker merlons. It is quite clear that the Romans not only built in horizontal stints (like Hadrian's Wall, divided between centuries, each doing a few paces length) but also vertically (one gang doing the foundation of the wall, the next the main body, and so on; Peter Hill's recent book on the construction of Hadrian's Wall makes this quite clear). Add to that the problem of brick supply (were they stockpiled beforehand or did they have kilns churning them out as they built it on a just-in-time supply system, which would mean that different firings might be slightly different colours?).

Mike - I appreciate that these structures were built in sections by different gangs, and the point is well made via reference to work on Hadrian's Wall. However, the bricks on the crenellation level appear to have weathered more (poorer quality), and the workmanship is noticeably different. There are portions where the perps are nearly in complete alignment, whereas the lower courses really do appear from the photograph to be much better quality materials and workmanship.

Tarbicus' excellent work with the original photo really does highlight this even more IMHO.

Regarding the question of brick manufacture and stockpiling, there was so much construction in Rome at the time of the earlier Tiberian period walls, that I believe it is highly likely a "just in time" approach to the supply chain would not have been practical. Assuming that manufacture of these bricks did not fall under the direct control of the army (and I am thinking here of tile and brick stamps found in Britain as an example), it is more likely that a huge, and very profitable brick manufacture industry was thriving at this time (I do not recall seeing any research on this?). Quality could well have been an issue, but in the section of wall we have been looking at I think that there is a marked difference between the quality of the bricks in the three zones (or dare I suggest phases).

Fascinating :wink:

[Arahne]

Without seeing crosssection and publications about this castrum I 'll post few of mine thoughts.

- I see only differencies in colour ( tiles creating the merlons )
- Regarding building crews. THis is very specific kind of castrum wall since that it was built of bricks. I was considering if is it possible that civilian- building with bricks- experts built praetorian castrum in Rome(I dont know the word in english for common worker that builds with bricks)? There are two main parts in this wall that maybe need different kind of workers - foundation and wall courtain. I can not find any reason why you would change the crew when building the finishing part of the wall height - passageway with its merlons?
-regarding different colours of red bricks - different parts of structure behave differently through the centuries, especially regarding moisture-maybe this is why you observe different colours in lower and upper parts?
-in brick kiln do all the bricks have the same burning temperature achieved?

[mcbishop]

Mike - I appreciate that these structures were built in sections by different gangs, and the point is well made via reference to work on Hadrian's Wall. However, the bricks on the crenellation level appear to have weathered more (poorer quality), and the workmanship is noticeably different. There are portions where the perps are nearly in complete alignment, whereas the lower courses really do appear from the photograph to be much better quality materials and workmanship.

Tarbicus' excellent work with the original photo really does highlight this even more IMHO.

Barry, I see what you're saying but I still feel such variability could be just the product of different processes/materials being used at the same, as much as it could differences in time.

Regarding the question of brick manufacture and stockpiling, there was so much construction in Rome at the time of the earlier Tiberian period walls, that I believe it is highly likely a "just in time" approach to the supply chain would not have been practical. Assuming that manufacture of these bricks did not fall under the direct control of the army (and I am thinking here of tile and brick stamps found in Britain as an example), it is more likely that a huge, and very profitable brick manufacture industry was thriving at this time (I do not recall seeing any research on this?). Quality could well have been an issue, but in the section of wall we have been looking at I think that there is a marked difference between the quality of the bricks in the three zones (or dare I suggest phases).

As I understand it, brick manufacture in Italy was indeed down to civil contractors. Producing the quantities needed for the CP may have been more than one factory could manage, so that could explain differences between batches. Certainly could be 'phases' we are seeing, but possibly micro-phases in the same building process (foundations, curtain, string course, merlons) with different gangs concentrating on the different elements, as we know happened on HW.

Mike Bishop

[mcbishop]

Without seeing crosssection and publications about this castrum I 'll post few of mine thoughts.

- I see only differencies in colour ( tiles creating the merlons )
- Regarding building crews. THis is very specific kind of castrum wall since that it was built of bricks. I was considering if is it possible that civilian- building with bricks- experts built praetorian castrum in Rome(I dont know the word in english for common worker that builds with bricks)? There are two main parts in this wall that maybe need different kind of workers - foundation and wall courtain. I can not find any reason why you would change the crew when building the finishing part of the wall height - passageway with its merlons?
-regarding different colours of red bricks - different parts of structure behave differently through the centuries, especially regarding moisture-maybe this is why you observe different colours in lower and upper parts?
-in brick kiln do all the bricks have the same burning temperature achieved?

It isn't just bricks we are talking about here as this, like most of Rome, is made of brick-faced concrete (opus latericium). It is almost certainly civil brick manufactories providing the material (more than one?) and possibly even a civil labour force who would be more versed in building this stuff (would any emperor seriously have expected the Praetorians to do their own building work?!) but the basic building processes, working in gangs etc, would probably hold true.

Brick and tile do vary widely in colour when excavated. Most are shades of the usual red, but can range from black to yellow according to the conditions under which they are fired, so batches (fired at the same time in the same kiln) tend to be of the same colour. Of course, in the UK, we never excavate them in quite the quantity you see here!

Mike Bishop

[Arahne]

Well, we are making deductions based on bricks observed from your photos. I still say that I do not see any reason why You change building crew for finishing last parts of wall? Do you have any cross section sketches of this wall?
My point about darker colour of lower parts is that it is probably not from the changes in building technique but the reasons of structure behaviour through the time. Especially moisture. Sorry for my english expressions, I lack technological terms .
My experience is different regarding brick colour. I have seen in Sirmium different colours of the bricks in the same wall. That is why I was thinking for long time that it could be possible that from the one series of bricks you get different coloured ones. Although my observation is not based on experimental proof.

[Tarbicus]

What of the possibility that during its initial construction it had no crenellations, but only a month, or year or two later someone decided it should have them?

Anyway, more on the subject: Copy and paste the entire link

http://penelope.uchicago.edu/Thayer/E/G ... rope/Italy
/Lazio/Roma/Rome/_Texts/PLATOP*/Castra_Praetoria.html

[sulla felix]

Tarbicus,

I am with you on this, although the crenellation brickwork seems to show more weathering than the lower brickwork, hence my suggestion of poorer quality bricks/workmanship. This however assumes that we are looking at the wall from the outside of the fort. If we are looking from the inside, less weathering beneath the battlements would be expected.

Mike - view from the outside or inside?