A Philosophical Reading of Walls

I'm impressed with the thoughtfulness of this essay on wall-building as fortification technique. It contains at least two insights that are very much worth having:

1) Advances in weapons and advances in defense technology tend to mirror each other,

2) No matter what, defense in depth is necessary.

The relationship in (1) is a little more complex than the author suggests. It's not that advances in walls provoke advances in weapons, but rather that a two-way relationship exists between attack and defense. I drew up a slide to explain this for a conference once.

This was just a sketch of the issue for an academic audience; the more expert audience here will readily identify complexities I didn't bother to draw for them. The basic point is that swords got longer, and then they got shorter. Why? Well, armor got better and better for a while, meaning that it required more force to overcome. A sword is basically a lever, and the longer the lever, the greater the force at the end of the lever. Thus, longer swords.

After the advent of effective gunpowder weapons, however, armor was increasingly less effective and less present. Thus, swords got shorter again. Indeed, to a large degree they were abandoned in favor of the gunpowder weapons. They survive today as combat knives and bayonets, both normally considered last-ditch weapons whose use is preferably to be avoided in most circumstances. There is at least one example of an intentional bayonet charge from the Iraq War, as a way of attacking into an L-shaped ambush, but it isn't a go-to tactic anymore.

To return to the first article, I am impressed with the way the author treats the universals at play in defense. As he notes at the end, the question of the usefulness of walls remains up for debate. "Plato reckoned that walls encourage 'a soft habit of soul in the inhabitants, by inviting them to seek refuge within it instead of repelling the enemy.' Aristotle retorted, that not building walls was 'like desiring the country to be easy to invade.' It’s still an open argument."


Captain Steve said...

Interesting. Wonder how the Roman Gladius fits in with this theory? Legionary armor was at least as effective as that around the Norman Conquest, yet the Gladius was much shorter than swords of that era. I have seen at least one theory which asserts that as the Roman Legions got less effective, their swords grew longer--and attributed causality thereto.

Grim said...

I think metallurgy is the answer there: the Gladius was shorter, and a stabbing weapon, because the steel wasn't good enough yet for a long slashing weapon that wouldn't break on the armor. (Longer Roman-era swords tend to be pre-stirrup cavalry weapons, deployed not against heavily armored infantry but to disperse archers and skirmishers.) I gather that the kind of crucible steel they learned how to make around the Viking age was at first a real mystery to archaeologists, as they didn't think anyone knew how to get the steel hot enough to create super-high carbon steels for hundreds more years. A stabbing weapon like the Gladius could effectively penetrate the weak points of the armor, such as joints, that couldn't be slashed through with the swords they could make in those days.

One of the complications I smoothed out for this graph is the difference between slashing and stabbing weapons. Eventually the High Medieval armor got good enough that you couldn't slash through it with a sword of any length, so swords reformed to be more capable of a similar kind of penetration. The swords intended for use against armored knights ceased to have Fuller grooves, and instead became characterized by a diamond cross-section whose high central ridge would reinforce the point. You can see this by comparing and contrasting the Oakeshott type XIII, typical during the Crusades, with the type XV that develops later in the Middle Ages (1300-1500).

Captain Steve said...

Good information. Thanks. I would only add that perhaps changing tactics also contributed, e.g Roman heavy Infantry with light cavalry in support versus Medieval Heavy cavalry with stirrups(!) being the primary forces.