After reading far too much of the excellent Song of Ice and Fire series, I decided to look a little deeper into the knight’s best friend: A sword! I will not only be looking at the techniques used to create some of history’s most notorious weapons, but I will be exploring the physics behind them, from molecular structures to forces and pressure. This is A Game of Swords!

Anyone who’s anyone (when it comes to weaponry) knows that the most important part of any edged weapon is the quality and design of the blade. There’s no point slashing at your opponents with blunted edges, and you’ll never pierce anything if you have an inferior tip, so how can we go about ensuring that our sword is going to start sharp and stay sharp? The first thing to look at is the material you are using. The most ancient swords, used by the Mayans and Aztecs, were little more than wooden clubs with obsidian chips laid along each edge. Obsidian, made up of Silicon Dioxide with mixed oxides of Magnesium and Iron, is a more a metallic glass than a pure metal. It is this glass like quality that makes it great for sword making, as it is extremely brittle, and will fracture into very sharp pieces. This is all very well, if you happen to live near a long dead volcano, but for the tribes-people of Europe there had to be another way to forge a weapon. The ancient Greeks relied heavily on bronze weaponry, as this alloy of Copper and Tin was strong, sharp and easy to make. Due to the metals used, it was very easy to cast and forge into weaponry. Even late into the iron age, Roman officers carried finely decorated bronze swords into battle. The eponymous Roman sword is the Gladius, which was a very simple double-edged blade with a (relatively long) sharpened point. These swords were primarily designed for underarm stabbing, as in the heat of battle there is very rarely enough space to swing anything larger than a shortsword! The Gladius and its cavalry equivalent, the Spatha, dominated the battlefield for centuries, allowing the Romans the flexibility that they needed, as it only used one hand, the famous rectangular roman (or its rounded sister for mounted combat) shield could be held in the other, offering ample protection for infantry and cavalry alike.

The blades of the common soldiers were actually cast from iron at first, as the early methods of casting it created rather brittle weapons that were prone to breaking. Iron was however much more abundant than copper and tin, and smithies soon started pioneering new techniques to create stronger blades. In East Asia, the metal was often forged from special Tamahagane steel, made from different mixtures of iron sand, which creates an incredibly strong mixture of alloys, perfect for each individual part of the blade. This steel was then folded upon itself repeatedly, creating an edge sharp enough to split a bullet in two (http://www.youtube.com/watch?v=OBFlYwluqMk – skip to about 45-60 seconds to see the slo-mo footage). Steel is so strong because of its crystalline structure, which is created when molten iron is mixed with Oxygen. This is because iron ore contains a lot of carbon atoms. When the iron is cast it will lose some of these carbon atoms, but the more there are, the more brittle the iron becomes. By controlling the amount of oxygen that flows across the steel, the hardness and potential sharpness can be controlled, allowing the smithies to tailor-make their raw forging material. If the steel is more malleable, it can be forged into a stronger weapon, with more interesting curves, but may blunt a lot quicker. In this way a sword can be made from composites of flexible and inflexible steels, with sharp, brittle edges and a flexible body. This is the point at which sword making reaches its zenith.

But now we have our alloys, how do we decide what sort of sword we want? Should our sword be held in one hand, or two? A light sword is good, but would a heavier sword cause a more devastating blow?  The answers to these questions are largely situational, but there may be a physical reason to choose one weapon over another. It all comes down to how much pressure you can apply, and how much pressure your opponent can resist. Pressure is simply the force applied, divided by the area that it is applied to, so greater force equals greater pressure, right? But the force in a sword swing comes mainly from momentum (and therefore the weight) of the sword. So if we want a greater force we’ll need a bigger sword, but a bigger sword means you’ll need to be stronger to actually do anything with it. This is all very well if you’re the knight with the rippling muscles, but what if you’re the poor gangly footsoldier? In that case, would it not be easier to reduce the area that the force is applied to? Especially if your opponent is wearing plate armour and heavy chain-mail, you’ll need something that has a chance of piercing through all those layers (and hopefully your opponent). This is where pointing swords, such as the Rapier come into play. These allow a great deal of pressure to be applied by stabbing forward with the tip of the sword. The smaller and sharper the tip, the greater piercing power your sword has, and the more likely your enemy is to get a bellyful of steel! most of these swords still had two sharpened edges, just in case, but occasionally, a soldier would be so confident of his thrust that his sword would have no edge at all!

Let us suppose we have our stocky knight in his heavy plate armour, with a big, heavy broadsword. On the other side of the field we have the gangly footman, épée in hand, dressed in some cheap chain-mail and an ill-fitting helmet. The knight is a sure bet, right? Wrong! Let us say that the knight’s armour can withstand a direct hit of 2000 pascals of pressure on his breastplate. In anyone’s terms that’s an awful lot of pressure. Now the footman’s épée has a finely crafted tip, 0.5 millimetres across, and his sword weighs about a kilogram. Our footman, quick as an arrow, lunges at our knight with an acceleration of  10 metres per second per second. Newton’s second law states that F=ma, so our footman hits the knight with a force of 10 Newtons. That might not sound like a lot, and in everyday terms it isn’t, but when we feed this value into our pressure equation (bearing in mind the standard length unit is metres), we get a value of 20000 Pascals! Ten times more than the knight’s armour can withstand! Needless to say, the footman would need to give his sword a bit of a clean before he sheaths it again. The outcome might have been different if the knight hadn’t been encumbered with such a heavy broadsword, and indeed, when using a heavy weapon it is always best to be accurate, and better to be well prepared!

Thus we have seen how versatile the humble sword can be, ever the choice of officers and laymen alike, the humble blade served us well for thousands of years. We can see that swords, as well as strategies, can be adapted to suit any situation, and now know that as long as your blacksmith is good enough, you’ll never go unarmed or unprepared!

Harry Saban – The Octave Doctor (Phd Pending)

Sources:

Wikipedia (We’ve all done it, so don’t judge me!) – History of Swordmaking and Steelmaking.

http://www.ehow.co.uk/about_6638014_atomic-structure-steel.html – Atomic Structure of Steel

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