Arab invaders, knights, and feudalism

In the 9th century, the Frankish kingdom was under attack from all sides. Vikings from the northwest and Arabs from the southeast. Martel and other Charlies discovered a new fighting technique: mounted shock troopers, also known as knights.

Rather than using a spear on horseback as before, knights would keep the spear affixed directly to their shoulder and wrap their arm around it to guide it. Then, when the horse charged and the lance tip found its target, the full force of armor, horse, and rider (1500 pounds) would be administered through the lance tip. This had a predictably devastating effect, so much so that the lance would enter its subject and remain lodged inside, effectively disarming the attacker. High backed saddles and stirrups provided the necessary stability to keep the rider on the horse at impact.

But everything about this new way of fighting was fabulously expensive. There just weren’t enough people in the ruling class to staff the armies required for this. This was one reason for the feudal system, where a vassal could swear fealty to his lord and receive lands from which he could profit, in exchange for providing military service on the lord’s behalf. This land would then provide a means of income from which the knight could supply himself and the required entourage: multiple horses, armor, squires, training, etc.

Source: Early Middle Ages

Heavy knights and destriers

More knights means more horses, and not just more, but stronger ones to carry the weight of knights and their armor. War horses, also known as destriers became the norm for knight mounts.

Source: Medieval Technology and Social Change by Lynn White

Stronger horses and farm yields

War horses interbred with draft horses. Thus, more horses were available for farmers, displacing oxen as draft animals. And increasing farm yields because of their superior speed.

Source: Medieval Technology and Social Change by Lynn White

Heavy plate and heraldry

Another side effect of heavier armored knights is that by the late Middle Ages, knights and horses were often fully covered in plate. This made identifying them at tournaments nearly impossible. Thus, there was a need for identifying marks, and we have the advent of heraldry.

Horses in agriculture and the three field system

Another invention that increased farm yield at the time was the three plot farming system. By planting summer crops on one plot, winter crops on another, leaving the third field fallow, and then rotating the fields every year, farmers gained several things. First, instead of 1/2 of the land being used, now 2/3 of the land was used. Second, the three-field rotation led to more fertile soil, since legumes fix nitrogen in the soil. Third, one of the most popular winter crops was oats, which turned out to be a far more effective food for horses than grass.

Source: Medieval Technology and Social Change by Lynn White

Horses, peasant mobility and urbanization

More peasants had more access to horses, which gave them more mobility. This had several important implications. First, farmers could now get to the market on their own where ordinarily they would be reliant on merchants. Effectively this reduced shipping costs for farmers and made their whole operation more profitable. Further democratizing transportation were improved wagons. Up to now, these had been two wheeled, but by the 13th century, a four wheeled version emerged. Whippletrees allowed multiple animals to pull heavier plows, pivoted front axles greatly increased maneuverability and adequate brakes were increasingly available.

These changes allowed peasants to farm land further from a river — the highway system of the Middle Ages. This in turn meant more farms in the land, and an increase to general carrying capacity. An increase in population is highly associated with prosperous times (the contra positive holds). A second benefit of horse-based mobility were more living options. Now peasants could live in larger towns and ride to their farm every morning to do their day’s work, then return to their town. This increased their prosperity in many ways, giving them access to schools for their children, more power to self-govern via communes, access to culture, pubs, and other amenities found in a Medieval towns.

Source: Medieval Technology and Social Change by Lynn White

Counter-Knight missile innovation crossbows, longbows, and muskets

Knights engaged in mounted shock combat were initially a Frankish super-weapon. Inevitably, it spread to other regions and kingdoms, including Arabs and Byzantines. Plate mail was very effective against missile weapons of the 9th century, which mostly consisted of short bows. In response to the proliferation of knights, the crossbow emerged as an effective ranged deterrent, perhaps rediscovered or perhaps imported from China. Unlike an arrow delivered by a short bow, a crossbow bolt that found a knight would pierce through his plate and do significant damage. The main drawback of crossbows was the slow reload time. By the 13th century, the English borrowed and perfected the Welsh longbow, about as tall as a man, with an impressive 100lb pull force. Combining the short reload time of a short bow and the wallop of a crossbow, the only drawback was that it was difficult to master. The longbow was murderously effective against charging knights, especially with hundreds of longbowmen firing volleys in quick succession. Equipping a longbowman was far cheaper than equipping a knight. This raised the status of peasants: now they could once again hold a important position on the battlefield.

Muskets came later but occupied a similar niche: a group of musketeers buttressed by pikemen spelled disaster for charging knights. Pikes were longer than the knight's lances and could be planted into the ground. Meanwhile musketeers would mow down a group of knights.

Source: Late Middle Ages

Increasing costs of human labor and mechanization

Human labor was very cheap in the early middle ages. Late Roman practices of employing agricultural slaves, and enlisting more slaves as war booty continued to be popular. Towards the high middle ages, slaves were replaced by serfs since lords found that emaciated slaves were not very effective workers, and the practice of selling slaves and splitting families was not conducive to propagating the slave lineage. As mobility increased, serfs could escape to towns, hide for a year and gain legal freedom. Other paths to freedom included going to the frontier, where lords wanting peasants to develop their regions would offer peasants freedom and a small slice of land to farm.

The cost of labor went up further after the population was decimated by the Black Death and the supply of peasant workers plummeted.

As the cost of human labor went up, old mechanical power devices that were initially not economical were rediscovered. The water mill was known in Roman times, but just didn't make economic sense: a slave gang could more cheaply rotate the millstone directly, Roman slaves were cheaper than machines. Windmills could operate in northern Europe even in the fall, when streams driven by ice melt dried up, and even in the winter, when rivers would freeze over.

Power shift from lords to peasants and kings

Peasant revolts in England, France and Spain were quickly quashed, but still gave peasants a sense of sovereignty. Further, peasants commanded higher wages and kings gained legitimacy and power. Lords were squeezed by a variety of other factors on all fronts. Towards the end of the middle ages, this led to centralized power and the end of the distributed feudal system.

During periods of war, kings would often rely on mercenaries, paying them to participate in individual skirmishes. However some of the most violent periods came during peacetime when heavily armored men were no longer getting paid, and so set to indiscriminately plunder the countryside. This resulted in an increasing practice of royal standing armies, strengthening royal power and reducing reliance on knights.

Technologies reducing noble power:

• Cannons: rendering their own castles less effective, less security at home.
• Longbows and gunpowder: rendered their offensive capabilities less effective, rendering them less effective offensively.

With dwindling military effectiveness of knights, there was no longer need to amass large knight armies, or for the feudal system at large. Cannons were prohibitively expensive, so could only be acquired by kings.

Thus the feudal noble class was squeezed out of existence, and many nobles became salaried courtiers employed by kings.

Source: High Middle Ages, Late Middle Ages, Medieval Technology and Social Change by Lynn White