The science
The key to a harness of armour is to balance protection against mobility. The knight needed to be able to fight as well as withstand an onslaught from a variety of weapons. Although a complete harness could easily weigh in excess of 30 kilograms (66lb), the weight was evenly distributed about the body and securely held in place by attaching the parts to the underlying arming doublet, or aketon.
Extremely fine workmanship enabled a variety of joints to be used for articulation – from 'sliding rivet' joints at the elbows and knees (couters and poleyns) to 'turner' joints in the upper arms (vambraces). To aid mobility, some harnesses were made with steel sheets that were hardened to give equal protection at a lighter weight. Other suits had thicker metal on the left side as this was usually more vulnerable to attack from right-handed swordsmen. But for all this innovation, how much protection could steel really offer?
At full tilt
During tests at the Royal Military College of Science Testing Ground at Shrivenham, a basic coat of plates received a mechanical blow from an iron tip equivalent to a man being struck by a lance at full tilt. Although the plate was pierced, the aketon worn underneath was unmarked.
A similar test involved a hardened-steel breastplate in the style of the 15th century. A bodkin arrow hit the plate from a distance of 20 metres (65 feet) – the equivalent of a 140mph impact. The steel was penetrated but, again, there was no detectable harm to the doublet worn underneath.
Shock waves
So was the knight invulnerable? Not quite. In a further test, the breastplate was set over a gel block and then hit with a pole-axe. The vibrations in the gel showed that massive shock waves would have been transferred through the metal, possibly causing trauma to the body inside.
But though the knight faced a variety of concussion weapons, such as the two-handed pole-axe and mace, by far his biggest enemy was heat exhaustion. Only a few minutes' fighting in a full harness of armour sends the body temperature soaring. An exhausted knight in the centre of a battle was a dead knight.
