Fortifications: Why walls of stone and not of earth?

[Peroni]

Of course the raid on the Medway, just two weeks before, is usually forgotten.

On the contrary! We were getting trounced by you guys!

de Ruyter bombarded Sheerness, went up the River Thames to Gravesend, then up the River Medway to Chatham, where they burnt four capital ships, and towed away the Royal Charles, pride and flagship of the English fleet!!

Then he decided to invade Suffolk (hehehehe) It's amazing what firing into flint shingle beach can do to repel attackers! The wounds must have been horrendous.

[Praefectusclassis]

I meant, as far as I understood, that in general the Brits try to forget that particular raid. I know the effect, bits of the Royal Charles are still in our national museum.

[L. Aufidius Pantera]

The Lunt gate is fixed??? *Grabs camera and scrambles into car* - great news, last time I was there (last autumn? or was it the year before?) it was all full of barriers and scaffolding and you couldn't see a thing!

C.

[Emeraldweapon7d]

didn't fortifications go back to "softer" materials on the principal that they would slow/stop the rounds rather than shatter? Sort of like backstops at shooting ranges made from dirt mounds.

[Tarbicus]

I meant, as far as I understood, that in general the Brits try to forget that particular raid. I know the effect, bits of the Royal Charles are still in our national museum.

It was a long time ago.

It's been featured in a couple of documentaries I've seen here.

[Felix]

didn't fortifications go back to "softer" materials on the principal that they would slow/stop the rounds rather than shatter? Sort of like backstops at shooting ranges made from dirt mounds.

Exactly. Stone is brittle, compared with rammed earth. So forts were made with very thick walls, mostly of earthen fill, with a hard skin of stone or brick to shed water and ease maintenance in between wars. With the advent of cannon, a high wall became a hazard, as it is easy to undermine (with cannon balls) at its base, and then collapse. There is a nice American example of 18th century fortification at Ticonderoga, in New York.

http://members.tripod.com/~FortTic/Fort.html

[D B Campbell]

So far, I think we've overlooked two important factors.

(1) Availability of suitable materials. The Antonine Wall in Scotland, for example, was built of turf and timber, presumably because the raw materials were plentiful and could be quickly and easily assembled. Stone construction is more time-consuming.
(Note that many originally turf-and-timber fortifications in western Europe were eventually rebuilt in stone, implying that stone was perceived to have advantages.)

(2) Prestige. A stone wall is far more impressive than a timber palisade or an earth rampart, which may be a consideration if the wall is more than simply defensive. A fort wall is utilitarian -- no one particularly cares what it looks like, as long as it functions --, whereas a town wall makes a statement.

Just a thought ...

[L. Aufidius Pantera]

Bear in mind, though, that the Antonine Wall does have a stone base (at least in places...) presumably to counteract the turf rampart sagging. And I only buy availability of resources to some extent, seeing that forts on the Dutch limes where eventually built in stone, despite there being no suitable quarries in Germania Inferior and the stone actually having to be quarried in the central Rhine area (Germania Superior) by special detachments...

Th prestige point, however, is interesting...in a sort of 3rd century central and southern Gaul sort of way...

C.

[Robert]

Although by no means an expert, in view of a proposed reconstruction of a full-scale castellum, I have delved into their construction along the Limes in Holland. At first, the castella had turf walls with a rampart of wood at the top, similar to the picture shown. These were constructed using the turf cut from the central hectare to be cleared and the trenches outside. The wooden rampart was made from locally found trees. It was only when the empire became more entrenched and the "Roman peace" descended on these parts that trade picked up and better wood and stones were imported from Germany. This is also the time the roof tiles and bricks appear, produced in Nijmegen and in field kilns. The building fazes of a castellum can be seen on the site www.pragris.com , documenting the archeological excavation of a well preserved Dutch castellum, showing it's groundplans through time.
I feel the discussion is not on the better/worse scale, but was governed by local availability of resources at the time of building.

[D B Campbell]

I feel the discussion is not on the better/worse scale, but was governed by local availability of resources at the time of building.

Glad you agree, Robert!

[mcbishop]

I feel the discussion is not on the better/worse scale, but was governed by local availability of resources at the time of building.

Let's kick the tyres and light the fires and add to that the 'need for speed' - the western half of Hadrian's Wall was completed as a turf rampart and it has been suggested that this is because the whole thing was getting a little bit behind schedule (nowhere near as bad as Wembley Stadium, probably, but you catch my drift...). A rival suggestion, that there was no suitable building stone available, suffers from the major flaw that it was indeed later rebuilt in stone.

Hadrian's Wall actually adds something else to the equation and that is that permanence is dependent upon maintenance - a turf and timber structure can last as long as a stone one if it is maintained (anybody been on HMS Victory? Anybody care to guess how much of what you can visit today was actually at the Battle of Trafalgar rather than growing in a field somewhere at the time?). Turf slumps but it settles eventually and can be consolidated; timber tends to rot at one point (the interface between air and ground) and good structural oak can last for years (as the many medieval timber-framed buildings in the UK will attest). Analysis of the structural timbers from Carlisle has shown the use of alder in the earliest phase, a truly crummy building timber but one that would have been easily available when the site was first cleared, as it was next to a major river floodplain; alder for structural use has a life of around ten years before it requires replacement (so I am informed) so it had the major plus factors of being available, quick, and okayish for a decade.

The Roman military were fond of building in clay-bonded stone in the first part of the 2nd century and saw no reason why they shouldn't build the Wall in the same material - after all, they had used it in all their military bases for a while. The problem is that clay-bonded stone is an active medium that depends upon rendering to help the wicking process whereby water is drawn up into the walls keeping the clay matrix just plastic enough for it not to crumble but not so sloppy that it collapses. Don't maintain it, subject it to a bit of rain and frost, and the whole mess comes tumbling down (as it did at Wallsend, Housesteads (repeatedly), and Chesters - in fact virtually anywhere where the pre-mortared curtain has been examined).

Fashion too has to be considered - a whole range of techniques of defence construction were used in Britain just for turf-and-timber fortifications (turf cheeked, clay cheeked, solid clay, baked clay, full box rampart, half box rampart; timber corduroy base, brushwood base, cobble base and so on and so on). Britain was even hit by a wave of box-rampart building in the Flavian period. Why? It is at least a possibility that all such developments, features, etc were on occasion the whims of praefecti castrorum, so we may not be dealing with a truly linear process in development or adaptation (just as I keep saying with helmet typologies, not that anybody ever listens...) but rather just what felt good or right at the time, what was easy to do (remember 'cheapness' is never a factor in the Roman army because they had the ultimate irreducible resource to play with: manpower), and what was quick.

Mike Bishop

[Robert]

He Mike, Oh yeah, I'm sure practicality and the need to knock something together "chop-chop double time" did play an important role. We saw the use of alder and the likes here as well in the earlier stages of construction. Anyone visit the Pragris site, by the way? Story here was pretty liniar.