Fortifications: Why walls of stone and not of earth?

[Eleatic Guest]

The other day, I was asked what advantages stone or brick walls actually have over rammed earth or mudbrick walls? Conventionally, the latter are more associated with the bronze or iron age and the former rather with classical and medieval times, but are stone or brick walls actually an improvement? And in what respects?

[Tarbicus]

Interesting page here:
[url:1jkao4sb]http://www.consumerenergycenter.org/home/construction/earth.html[/url]

Unfortunately, rammed earth construction is very labor intensive. It can take many hours to properly tamp dirt into the forms, then take the forms down and set them up again for the next section of a wall. This laborious process makes rammed earth construction more expensive than traditional frame and stucco building, and most of the homes currently built in this way are custom homes.

[Felix]

First answer (an obvious one): mud brick can only be made in places with the right climate. In Ireland, for example, mud brick is just going to be mud.

Second: I believe you can build higher and thinner with stone or fired brick. Mud brick was used for Mesopotamain ziggurats; and in order to build high, the bases had to be massive, and reinforced with logs (as I recall) across the top of each layer to keep the lower layers from crumbling and splitting. The Egyptians build pyramids of a roughly similar shape, and these did not need reinforcement (although if built too steeply, as in the Bent Pyramid, could fail) to the same degree. A thin wall is not an advantage as such; but a wall could be build higher for the same base thickness with a harder material, and height was a good thing.

Third: maintenance. All walls collapse (see Robert Frost ). However, a wall of stone may last better than one of rammed earth; and if it does fall, the blocks are relatively easy to pile back up again.

Fourth: mud brick and rammed earth may be more vulnerable to very low tech assault (i.e. pick, dolabra, etc.) than stone. In a situation where large numbers of less technologically sophisticated folk are besieging a small number of defenders, this may be a real problem.

[Eleatic Guest]

Good points all.

...but a wall could be build higher for the same base thickness with a harder material, and height was a good thing.

That's what I thought, too. Earth ramparts have no good height-width-ratio because their profile is too 'triangular' compared with leaner stone or brick walls. This makes them rather inefficient not only in construction, but also in defense when the attackers can scale the earth walls without technical aids like ladders or siege towers.

.mud brick and rammed earth may be more vulnerable to very low tech assault (i.e. pick, dolabra, etc.) than stone.

Yes, but the amazing thing is that mud brick and rammed earth walls are on the other side pretty invulnerable against otherwise effective high tech assault tactics, namely sapping and catapult shelling! More, much more than stone and fired bricks.

[Arahne]

Stone and brick constructions last longer . When camps became permanent durable material was used for building them.

[Robert Vermaat]

Yes, but the amazing thing is that mud brick and rammed earth walls are on the other side pretty invulnerable against otherwise effective high tech assault tactics, namely sapping and catapult shelling! More, much more than stone and fired bricks.

Goes to show the action and reaction of defences and siege science. Stone makes better walls, leading to the development of better siege techniques. When cannons were invented, it was back to 'good old' earth again!

[S SEVERUS]

Nice pic. Is that somewhere in Holland?

What about the walls of the oppida in Gaul? Didn't they made stone walls withe a wooden frame work?

[LUCIUS ALFENUS AVITIANUS]

Some roman walls are maded in stone, but with a core earth. The roman wall of Tarraco is made with two paralel walls of stone blocks (opus quadratum) running over a basis of very large (+2m) iregular stones (opus siliceum).

The space between the two paralel walls are filled with earth or mudbricks without cooking (lateres crudi). The advantatges are clear: less stone blocks are needed. For the archaeologist it have a clear advantage: the earth contains some pottery sherds, and that gives cronology. :wink:

The postartillery walls are maded of earth, but almost always have covered with concrete to avoid the erosion by meteorologicall agents (rain, snow, wind, etc.)

The gaul oppida are maded with earth covered with stone walls but with a ingenous sistem (opus gallicum) described by Julius Caesar: The interior are reforced with some wooden frame linked with iron nails, giving the walls a great strength.

[L. Aufidius Pantera]

is that pic Bourtange? Vaguely remember running around there as a wee bairn...the fun we had!!!!

A major factor was probably maintenance of earth ramparts...have a look at the Lunt Roman fort in Baginton, where a section was reconstructed in the 1970s. Now thats about 30 years ago, but the ramparts have sagged so baldy by now that it wouldn't be difficult to climb through, particularly if you look at the wall to the right hand side of the gate - big gap beneath the wooden superstructure!

Surely stone walls need upkeep, too, but I don't think anything in the way of returfing every 20-30 years! So my guess is a combination of effficiency in terms of maintenance, combined with durability. But I'm just guessing!!

[Praefectusclassis]

It's Naarden, the Netherlands.
Other examples are Heusden

This is Bourtange:

[Eleatic Guest]

The postartillery walls are maded of earth, but almost always have covered with concrete to avoid the erosion by meteorologicall agents (rain, snow, wind, etc.)

The curtain walls were rather made with fired bricks with earth in between. I know because I have been lately often to the last German border fortress of the old artillery days. :wink: Concrete is much more a feature of 20th century fortifications.

Germersheim (German-French border fortress, built 1840)

[Eleatic Guest]

So my guess is a combination of effficiency in terms of maintenance, combined with durability.

Hm, I do not think that these maintenance reasons could have been so important. Legionaries did not fight either with stone axes, although they may have been more easier to built and maintain than the gladius. An easily maintenable fort is of no use when it becomes controlled by the enemy. The key to the shift to stone and brick must rather lie somewhere with its defensive qualities.

[LUCIUS ALFENUS AVITIANUS]

Another forts:

Bellegarde, France:

[Peroni]

Landguard Fort in my home town... Very similar design..a seven casemated battery.

"Overlooking the Orwell Estuary, the Fort has a long and rich history. Originally a fort was built at the behest of Henry VIII. The later fort of 1625 was the last fort in England to oppose a full scale invasion. It was on 2nd July (Julian Calendar) in 1667 when Captain Nathaniel Darell and 400 of the Duke of York & Albany's Maritime Regiment, with 100 gunners and 51 cannon, successfully repelled Admiral de Ruyter's Dutch force of 2 to 3 thousand! It is still remembered today".

I have Dutch ancestry, perhaps my ancestor was taken prisoner during this battle?

http://www.btinternet.com/~mervyn.lemon/lft.html


The photo of the turf and timber reconstruction of the Lunt Roman fort, Baginton (Above) 'Lunt Now' is slightly out of date, as the gate house has been fully repaired and is accessible to the public. The rest of the rampart has however been left to dissintegrate!

[Praefectusclassis]

It was on 2nd July (Julian Calendar) in 1667 when Captain Nathaniel Darell and 400 of the Duke of York & Albany's Maritime Regiment, with 100 gunners and 51 cannon, successfully repelled Admiral de Ruyter's Dutch force of 2 to 3 thousand! It is still remembered today

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