#warhorses

This post is in honor of @warrioreowynofrohan, who asked the question in the comments under my guide, "Horses: Since There Seems To Be A Knowledge Gap". Their question, "Given what you said about too much weight breaking a horse’s spine, how did that work with knights in plate armour?" is one I'm going to try to answer here, since the answer can be very nuanced depending on where and when you're talking about.

Also, while I was a stable hand for years as well as a rider, I never had the opportunity to directly learn more ancient styles of tacking, horse training, and combat, so I don't have any direct experience to draw from with regard to horses used for military purposes. I'm still gonna do my best here with what I know, and research what I don't.

As I've covered in the past, large horses (draft horses) make less-than-ideal warhorses, and so do carriage horses like the elegant and dramatic Friesians.

Let's begin by addressing this from the perspective of creative writing. For you writers and content creators out there, an essential part to the continuity of any historically-themed work you do involving horses will be depicting breeds of horses that didn't exist before a certain time in history. I'm going to approach this question from the stance of, "Medieval-type era warhorses". Horses were used in warfare as late was World War II, but actual horses you ride into battle with knights and archers and bannermen? We actually have to drop the subject of specific modern breeds altogether aside from using them for comparisons.

When discussing warhorses, various cultures have approached them differently. Some cultures will value a specific type of horse above all others, such as the Mongolian Steppe Horse or the American Mustang. Other cultures, which may be from biomes and territories where multiple types of horses are needed for different forms of warfare and tactics, value whichever horses can get their jobs done without their riders getting killed.

Carrying vs. Pulling:

Horses have been used in warfare since as far back as 4000 BC, but their first applications were more as chariot horses. Humans have been riding and working with horses since before we even had stirrups to more easily ride them with! As archaeologists and anthropologists make more discoveries, the more we learn that we humans have been working closely with horses since before we had specialized tools to ride them with. The very first warhorses pulled chariots or carts, which is much easier for a horse's anatomy to handle compared to carrying a heavy weight like an armored rider on their backs, which puts stress directly on their spines where they have very little supporting muscle for supporting a lot of heavy downward weight.

Warhorse Size Categories:

Really, any breed of horse can apply to a niche in warfare if it's needed enough. Even very small, delicate horses have had their place in the history of human combat! Before I continue, it's important to know that there's a unique unit of measuring a horse's height. Rather than measuring a horse's height in centimeters or inches, they're measured in units called "hands". A single "hand" = ~4 inches/10.16cm, and a horse's height is measured based upon the distance between the bottom of their hoof to the tallest part of their shoulders, just at the base of the back of their necks. We don't actually include neck length/head height in a horse's measurements with traditional measuring.

Another rule of thumb: The average horse cannot safely carry anything heavier than about 30% of their total body weight. This is a serious factor to take into mind when deciding on a type of or breed of horse for a mounted warrior of any kind: You need to factor in the OC's starting body weight, and then add on the weight of armor, weapons, and any armor the horse itself may wear along with the weight of its tack.

Light-Weight Horses:

A few examples of lightweight horse breeds whose ancestors have historically been used in combat are Arabians, Barber Horses, and the magnificent Akhal-Teke. Lightweight and delicately-boned horses like those are best applied for military maneuvers that require precision, speed, and endurance, and the rider themselves should specialize in some form of combat or reconnaissance that doesn't require them to wear heavy metal or laminated armors. Archers are good candidates for riding smaller horses, or lightly-armored swordsmen like an Ottoman Janissary.

Central-Asian and North African horses also benefit from having a higher tolerance for hot climates. They can absolutely suffer from heatstroke and cardiac arrest from being forced to run and work in extreme temperatures and should always be provided with the same protective measures in a heatwave as any other horse, but they have a little bit of an edge over horses descended from freezing and temperate climates.

Medium-Weight Horses:

Medium-weight horses started showing up in the archaeological record around about the Iron Age, where chariot warfare was becoming an increasingly utilized form of mobile combat, and people needed bigger, stronger horses capable of pulling heavier loads - such as a chariot with two passengers rather than just one. As cultures began to develop heavier-duty armors made of metals and laminated materials, it also became important to breed horses that were tall and stocky (muscular and with relatively short spines compared to their height), and therefore more capable of carrying riders in increasingly heavy armor. Medium-weight horses were also essential at the dawn of the gunpowder age when the cannon came into use in siege warfare for pulling the heavy, iron cannons into position.

Medium-weight horses are really where we see the beginnings of knights and other warrior classes on horseback come into the forefront of warfare. When you have a horse that's big and strong enough to carry heavier armor and heavier weapons along with a rider wielding them, you have a much deadlier force at your disposal. Strikes from a sword or spear from the back of a galloping horse basically results in a sword capable of cutting through enemy soldiers like a hot knife through butter.

Important Note: Traditionally, cavalrymen wield blunt swords when attacking from a charging horse's back. When a horse is charging at full speed, the sharpness of a blade becomes less important than the blade's ability to stay in one piece when it impacts hard armor and bone. A blunted edge basically turns a cavalryman's sword into a thin club that's better at holding up against smashing through multiple layers of armor and bone compared to a thinner, more delicate sharpened edge that can shatter from a high-speed impact.

Heavy-Weight Horses:

The direct ancestors of modern draft horses, such as the Shire Horse, only began to appear around about the beginning of the European Medieval Era, and were far and away not even close to the enormous sizes of the draft horses we have today. Any horse counts as a "Heavy-weight" classed horse if its weight exceeds 1500lbs/680kgs.

Heavy-weight horses were really more bred for pulling enormous weights rather than carrying knights. While yeah, there is some evidence that suggests that heavy-weight horses were used by heavily-armored knights, historians argue a lot about whether it was a rule or an exception (such as with Henry VIII, who continued to ride well after he had begun to weigh more than 350lbs/158kgs, and even went to war in France in his final years on horseback). Generally speaking, medium-weight horses tend to be the right balance of agile and strong for carrying someone that's going to actively be fighting. Heavy-weight horses were bred to be a lot more tolerant to the chaos and frightening stimulation of the sounds of battle, but medium-weighted horses generally tended to be more suited to moving efficiently through dense packs of soldiers and weaving around other horses.

Ponies:

While actually being the smallest class of warhorse, ponies were essential when it came to carrying cargo and working as pack-horses. In certain forms of terrain, such as mountains, large horses pulling big carts full of supplies or soldiers could often be extremely impractical. In situations where an army needed to move on foot and form a narrow line in order to travel, ponies were able to traverse much narrower and rougher terrain while carrying smaller loads to their destination, when heavier horses would struggle more under their own weight and dexterity.

Europe-Specific Terminologies:

If you're a writer reading this and writing a piece set in the European Medieval age, there are specific terms used for the different classes I listed of warhorses above that I'm gonna list:

Destriers: The Destrier was a universal term for the iconic knight-carrying, jousting horse. They were also sometimes referred to as "Great Horses" due to their reputations in combat settings. Destriers could have just about any appearance, but were rarely taller than 15.2 hands, or 62inches/157cm. They were capable of carrying heavily-armored knights (although knights in full plate mail rarely rode into battle and stayed on the horse the entire time - they tended to specialize at grouping up and killing a lot of footsoldiers swarming them at once and preventing breaks in defenses from being overwhelmed by an oncoming army; in the case of Edward the Black Prince, we have substantial evidence in the form of his surviving brigandine that a mounted soldier or knight was more likely to wear chainmail and brigandine with a tabard on their body with their arms, feet, and heads the most heavily armored in plate when they intended to fight on horseback, making them a little lighter and more maneuverable, but I may be waaay off base there because I'm thinking of more of Italian soldiers who used full plate and how they applied it in battle more than any other example) and wearing armor themselves.

Interestingly, the sex of a destrier was often chosen strategically. Stallions (horses that haven't been neutered) are more aggressive, and could both act as combatants on their own if their knight was dismounted or killed, but could give away an army's location if they were attempting to move stealthily. Stallions whinny and shriek a lot when they're horny or arguing with each other, which is most of the time.

Mares were often chosen by Muslim armies for being much less vocal, and therefore much more capable of stealth. Geldings (neutered males) were the preferred mounts of the Teutonic Knights, a Catholic military group, since they couldn't be stolen and used to breed more horses for the enemy army.

Coursers:

Coursers were the most common Medieval European warhorse. It's important to remember that in Medieval Europe, most armies were almost entirely comprised of common men - serfs subject to the will of their landlords, not far removed from slaves in many ways - who couldn't afford the highly-prized and expensive Destriers. Coursers were usually a bit lighter than Destriers, but were still strong enough to carry someone wearing armor. Coursers were also a little more utilitarian, because they were also sometimes used in hunting as well as warfare, so they had a valuable use outside of warfare that the owner could benefit from.

Rouncey:

A rouncey was an all-purpose horse that could be used for leisure and travel-riding as well as be trained for war. They were a lot more likely to be found on the farm of a serf or independent farmer of some kind, as they could fill a lot of different roles depending on what they were needed for. Their sizes weren't really important as much as their ability to get the job done.

"swan lake that"

So contrary to what I had thought, it turns out that destriers were not that much bigger than riding horses. (They did have other qualities, manueverability, stamina, aggression, etc. that were highly prized.)

What really mattered was less breeding in the narrow sense than training. Horses naturally shy away from things directly in their path, and a war horse needs to go completely against that instinct so that frontal charges go straight into enemy formations without losing momentum or changing direction.