In keeping with my ranting about aggravating animals in fantasy, I think I shall rant about horses. The second most overly romanticized and anthropomorphized animal galloping around DA, second only to wolves. And heck, the ol' Equus Absurdus may give Lupus Bardus a run for his money. This will be less pointing out ineptitude in storytelling and rampant cliche, and more about doing your friggin' homework before you write or draw horses. And watching Spirit doesn't count.
I'll be pretty blunt about the art side of things. Horses are Hard To Draw, and they are the Gods of being Hard To Draw. The only thing that I think might be harder is dinosaurs. (She said smugly.) Or possibly deer. When the grand masters of the Renaissance and contemporary master artists alike are stumped by rendering the correct pose of horses in flight, you bow before the king of hard art. Because everyone who sees you screw it up is gonna know it, especially those who have done the research. (Or those worst of smug sorts: equestrians, who don't need to be able to hold a pencil to know your 40-hour stallion picture is either cross firing or suffering a heart attack.) Even Spirit needed experts; and having said that, the only thing you could do worse is reference My Little Pony. Long, arduous hours await the equine artist, and while you can pull-off a half-assed wolf or whatever, it's extremely difficult to make a half-assed horse look even ... half-assed. Mostly it's whole ass. (Equine joke, get it?) It's very easy to fail, and fail on a great scale. Many horsie pictures deserve the MASSIVE FAIL watermark. Where are ya on that one, DA?
Anyway, moving onto horses in fantasy. The straight-up idiot will treat them like cars. You can gallop all day, let them graze at night, and wake up feeling perfectly refreshed in the morning. And on top of that, the horse will either be a true-blue companion or an utter bundle of useless, bolting nerves. The person who does mild research will realize how colic and such happens, but will probably screw up the names of tack pieces and even the parts of the horse. It's very rare to see anyone do the research from history, and if you're really lucky, you'll get someone who rides or is familiar with horses to some degree.
But fear not, because I can give a nice, long sarcastic list of quick reference for fantasy riders ... er, writers.
Mares - were moody, but excellent for raiding, because they are not likely to whinny at strange horses. Also, if they're in heat, and your enemy is riding stallions, you have a serious butchering advantage. Bedouin riders called their raiding horses "daughters of the wind" and preferred mares for the very reasons just listed.
Geldings were castrated stallions. The phenomenon of being "proud cut" is when a horse is castrated too late in life, and still retains all the traits of being a stud.
Stallions don't like other stallions. Hell, some of them will kill other geldings. There exceptions in temperament among every breed, but by and large a stud's first rule is "handle with care." Stallions who smell mares will, for the most part, throw every other thought out of their heads when mares in heat are near. They will climb fences and bust heads. A lot of fantasy authors tend to make stallions the ideal warhorse, and maybe they were, but I've never seen a knight dumped into the mud while his valiant steed hops a fence for a peasant mare. (I'd like to, though.) In George R. R. Martin's A Game of Thrones, there was a scene where a a pair of knights joust, one on a mare in heat, the other on a stallion. Best. Joust. Ever. 'Nuff said.
Now, medieval terms for horsies! Cause breeds weren't really necessarily established in the Dark Ages to Renaissance. (As a quick example, Rottweilers were called "rottweiler metzgerhunds", which means literally "the red-tile butcher's dog". They came from a town noted for their red-tile roofs, and worked cattle, hence the name. That's about as specific as one could expect for the time.)
Rounceys or hacks were simple riding horses. Grade blooded animals for the most part. If a peasant was lucky enough to own one, keep in mind that horses were harder to maintain then oxen, which could do plowing/pulling. Hacks in a fantasy setting would probably be seen in inns as rent-able mounts, pulling merchant and gypsy caravans, or as a mount for a guard or other low-ranked individual. Hack means "to ride", and that's what they were meant for. Which means no training other than bit and saddle. These are the sorts that will probably spook at nothing, bolt, or kill their rider running under a tree in panic.
Coursers were long-legged hunter/jumpers and runners, precursors to the modern Thoroughbred. They were very highly prized (and still are), and would be seen in a hunting/racing situation or possibly a messenger's mount. Coursers were extremely expensive, and being caught with one that didn't belong to you would be grounds for hanging if you were a peasant. So resist the temptation to have your orphan protagonist companion to a noble, gazelle-like sort, because it would be the equivalent of stealing a Lamborghini. All horses pulled their weight, and coursers were no exception, but keep in mind that nobility were the only class that could afford to splurge. As far as training, coursers would probably be more inclined to take a jump, but they could spook as much as any rouncey.
Draft horses were not warhorses! They were bred to pull plows and carriages and sledges. Most were bred in very cold areas, and so have the heavy coat as result. Barrels full of beer could kill a man if it fell on one, so imagine if you were a brewer who needed twenty of them sent somewhere. That's what draft horses were for. Again, they would eat a lot, so very poor families would probably have oxen instead. Low-class merchants and up would probably have a pair of drafts. Drafts would be trained to harness and yoke, but by the inclination of the breed, most drafts are not bolters. They cannot outrun predators, so they are more inclined to stand their ground and kick or bite. Drafts tend to be very mild-mannered, i.e. "gentle giants", and so are ill-suited to warhorse aggression.
Destriers were warhorses! Also called greathorses. Standing about 15-17 hands, mostly. (A hand is four inches.) Andalusian and many breeds seen in dressage like Lippazaners and Dutch Warmbloods were warhorses. "Warm-bloods" means a cross between the small, fierce breeds like the Arabian, "hot-bloods" and the large, slow drafts, "cold-bloods": the perfect middle ground. Dressage is a throwback to all of the training warhorses underwent. To survive battle, your horse had to be perfectly attuned to your desires in order to keep you alive. Destriers had extremely high levels of training: they could be ridden without reins and controlled entirely by the legs, including being told when to kick and with which set of legs. A lot of warhorse training is glossed over, with the exception of the charge. Every warhorse has to be able to charge.
Keep in mind that the stirrup wasn't invented until the Middle Ages and the invention thereof gave rise to the knight, but that Roman cavalry came waaaay before and perfected dressage/cavalry tactics even before that! Destriers were very, very expensive and highly prized, and that while some cultures thought the stallion was better, mares are not exempt from being destriers. Most often a knight rode a courser or sometimes a rouncey, and kept his destrier fresh for the coming battle. (And being a knight, you could actually afford that.) Also keep in mind that knights in full armor were not so heavy that they couldn't move if they got knocked off their horses; medieval armor weighed about as much as a modern-day soldier wears into battle, roughly 70lbs or so. So the idea that a draft was needed to carry the weight is kinda ... wrong.
Jennets or palfries were gaited horses and quiet/ladies horses, respectively. Often they were lumped together. Jennets made for an extremely smooth ride and were preferred by those who used sidesaddles (basically: women.) Jennets were also called "amblers" for their way of moving in a lateral gait or rack. Priests and friars, when they weren't riding mules or donkeys, rode palfries. Ill or delicate individuals rode palfries (singular palfrey). The Spanish Jennet in particular was a precursor to the Paso Fino and Peruvian Paso. As far as training, palfries would be the least likely to spook, because they would have been trained for that express purpose. Palfries would probably be older or retired horses, or horses extremely quiet in temperament to begin with.
I find myself oscillating between hating the horse-like-a-dog motif and despising the horse-is-not-alive motif. Ah, what the heck, I can hate them both! Horses are horses, they are not cows or dogs or some other animal you decide to substitute as a fantasy rider because you've never actually ridden a horse. Or saddled one. Or taken care of one. Petting a horse does not make you an expert. If you are writing fantasy, at least do your research. Talk to people who own horses and visit a stable or two.
The horse-like-a-dog motif is the "noble steed" complex; the hero's horse defends him from assassins, drags him to the fire in a rain storm, and follows him freely. Real horses are capable of loyalty and affection, don't get me wrong, but just don't stake your life on your horse choosing you over a bucket of oats after a workout. Prey animals simply prioritize differently from predators. On the flip side, horses are not unfeeling creatures; as a rule, they're extremely sensitive physically speaking. Their skin can detect changes in wind currents and they have nearly 360 degrees vision scope. Also, horses can overheat and run themselves to exhaustion very easily, unless they've been trained for it (as in a racehorse trained to run or an endurance horse trained to keep an effortless trot for hours.) Horses that are worked hard, then promptly fed and watered will probably colic. So don't have your hero gallop his horse to camp and feed it without a second thought, because I'll be expecting a dead horse in the morning.
Here are some more medieval terms for equine ignoramuses. Starting with the people who handled horses:
Hostlers were grooms or handlers of horses, usually a breeder or someone of some repute, as opposed to a stableboy. For example, if a mare was having a bad birth or a foal's confirmation needed to be judged, the noble would probably consult the hostler's advice. Hostlers were also trainers, by and large.
Farrier was another name for a blacksmith, but it specifically means someone who trims hooves and shoes horses. All farriers were blacksmiths, speaking medievally, but not all blacksmiths were farriers.
And moving on to tack:
Know the parts of your saddle. The front was called the pommel, the back was called the cantle. Jousting saddles had a high cantle so that a knight struck by a lance would not fly right off his horse's backside. (Also, do NOT put a saddle horn in a medieval setting, it came way, way later and was intended to drape a lariat over.) The seat of a saddle is, duh, where you sit. The most oft overlooked part of the saddle is the tree or framework. Trees had to be sized for horses, were made of wood, and covered in leather. If a horse fell over backward, they would probably break the tree and ruin the saddle. (Not to mention probably suffer a back injury in the process.)
Know the parts of your bridle. The bit is the metal dealie that goes in the horse's mouth. Not every culture used bits, mind you! Hackamores used pressure points on the face and the muzzle to basically do the same thing a bit did; also called a bosal, sidepull, or in medieval times as a jaquima (in Spain) or a sakama (among Moors and the like.) The throatlatch was a strap that wasn't always there, but it it buckled loosely beneath the cheeks of the horse to stop the bridle from being able to slide completely off.
Barding was horse armor! (It was not called horse armor; it was called barding. Wardogs also wore barding, and sometimes had wicked cool spiked collars or spears strapped to their shoulders, but we're getting off the subject.) A full suit of barding was Expensive with a capital E, and probably not super-comfortable, since it probably would have been cast with a general size in mind. (Not for a specific animal.) More common barding would have been leather and chain mail, rather than plate.
The chanfron was the horse's helmet, and could be made of leather or plate. It is also often called a champron, chamfrein, shaffron, chanfroin, or chenfron, because all these crazy European folks were running around at the time. If a horse had a horn on its helmet, it was affixed to a rondel, or a flat, round metal stud.
The crinet is the ridged scales of overlapping armor running down the horse's neck, also called criniere or manefaire. Chain mail could be affixed to the crinet to cover the flesh of the horse's neck.
The croupiere protected the hindquarters (akin to the crupper, a piece of harness that passes beneath the tail, and the two words are related), while the flanchard protected the flanks of the horse, and the peytral protected the chest.
If your horse wears the pretty flowing cloth seen in jousting matches and decorated with heraldic symbols, your horse is sporting a caparison. These cloths were part barding in and of themselves, usually heavy textile weave that could stop a spearpoint. Also, even the reins had armor, so they could not be cut! They would have metal coverings or be draped in chain mail.
And moving onto weaponry used on horseback:
The lance made the knight a deadly force on the battle field. Please note that if you have Apache warriors charging with javelins, it is going to be an extremely wimpy charge. What made the lance deadly? The stirrup! Roman cavalry had no stirrups; it was invented later. (And don't ask me who didn't think that one up right off the bat, but it's true. I sure as heck wouldn't have wanted to be in Alexander the Great's cavalry ranks.) If you are part of a charge, look out for pikeman. They will gut you.
Certain bows were created to be used from horseback. Normal bows like longbows draw in the middle of the bow; horseback bows were very tall and draw closer to the bottom of the bow. This was because the bottom part of the bow couldn't hit the ground or strike a stirrup while being drawn, but still needed power to make the shaft effectively kill-y. (If you have ever seen the movie The Last Samurai, one of the young warriors in the movie uses a fairly accurate horse bow.)
What Would Happen In Battle
First of all, do not ever, EVER have a character get kicked or bitten by a horse and walk away fine. First, horses can tear skin open and break bone by biting, and tear off fingers if they've half a mind to. (This includes little ones, too, like ponies and burros.) If your fingers tangle in the reins and the horse bolts, you can also look at losing some fingers. A kick to the head can kill you, and if the hoof is metal-shod, it can cut and crush. You could lose the top of your head to a slashing hoof, and don't even get me started on the shoes crafted with spikes! (They doubled as a way for the horse to have extra traction in mud.)
Second, horses have to be TRAINED TO TRAMPLE. A horse's natural instinct is to protect their feet; a prey animals natural reaction to keep what will save their life intact and whole. Cattle trample naturally; even horses in a panic that have room to run will dodge someone standing in the middle of the stampede with their hands outspread. (I, uh, wouldn't recommend it in an extremely narrow channel. You won't get the same results.) Therefore, a warhorse will trample and stomp because it has been trained to, but a regular riding horse won't.
Third, armor is not carte' blanche to injury. Armor does not equal invulnerability! Can I say that again? You can die fully armored without ever having the armor breached. How? The large majority of folks who survive the battlefield end up dying a couple of days later from internal bleeding. If you're hit with a giant maul warhammer, your armor will stop you from getting impaled, but the kinetic force will still be transferred by the blow. Later armor was engineered to basically absorb the damage, and could even withstand bullets (hence the term "bulletproof", in which armor would be tested to withstand black powder discharges), but that was late 14th-15th century, not Dark Ages. So if your hero gets slammed by a warhorse and trampled underfoot, they can still die. At the very least they had better be very, VERY bruised, extremely lucky, and possibly with spinal damage or dislocated limbs.
Fourth, a charge was a trained maneuver and was very freaking scary to be on the receiving end of. Battle was all about outmaneuvering the enemy, and cavalry's job was to outflank an enemy, or hit from a vulnerable or weak side. (Also, don't mistake cavalry, mounted force, for Calvary, the hill where Christ was crucified. It makes you look really stupid.) Infantry that gets charged from behind by giant, multi-ton armored warhorses trampling everything underfoot is guaranteed to break. When a horse steps on you, it's a bone-breaking disaster; the idea of facing down a line of mounted knights is downright piss-your-pants terrifying. So, unless you have a trick up your sleeve like Braveheart did, please don't have your hero coolly watch the oncoming horde and calculate how to take the first guy from the saddle.
So there. I don't want to read about any more flouncey horses floating blissfully through battle simply because they are a horse. In fact, I don't want to see any more stupid fantasy horses ever. You have no excuse after reading this!