From "Rich Men’s Skins; A Social History of Armour by K. J. Parker."
Rich Men’s Skins; A Social History of Armour by K. J. Parker — Subterranean Press
Greek hoplites created and persevered with military equipment that was (by our standards) inefficient, inconvenient and needlessly overengineered, because it was suitable for what they wanted out of war. They could make highly advanced composite bows when they wanted to, bows every bit as good as the Persians’, but they didn’t want to, because archery warfare would have changed the rules, spoilt the status quo, ruined everything. The Romans had no such compunction, their agenda being so very different; as well as innovating and inventing, they cherry-picked arms and tactics from every nation under the sun, but their successors, the Germanic barbarians, also drew back from progress in military technology, and for the same reason as the Greeks. Mass participation in war by common people in mass-produced armour was the last thing they wanted. It was the exact opposite of what they were fighting for.
We have to fast-forward a long time, from the Fall of Rome to the thirteenth century, before we come to a real change in armour, or attitudes. During that time, the Western European warrior’s outfit, consisting of a mailshirt and a simple conical helmet with a nose-guard, usually made of four plates riveted to a frame, hardly changed at all; hemlines rose and fell, as hemlines do, and we start to see a few helmets made from a single sheet of metal, but that was about all, and there’s no evidence of technical advance or any desire for it. Then, at the end of the eleventh century, westerners came into violent contact with a richer and vastly more sophisticated culture: Islam.
The First Crusade succeeded mostly through sheer ferocity. European knights, predominantly French and Norman, smashed their way into the Holy Land and took Jerusalem. In every aspect of military technology, from equipment to tactics to logistics, they were hopelessly inferior to their enemies; they succeeded largely through the element of surprise. For four hundred years, with only a few reversals, Islam had had no trouble defeating Christians; it was largely to internal divisions in the Muslim world that Byzantium owed its continued existence. The crusaders were, however, a different sort of Christian entirely. Unlike the Byzantines—it’s a sad irony that the most spiritual culture the world has ever known had to spend most of its energy and resources on war—the Crusaders wanted to fight; they were warriors, not soldiers.