Odd little mini-rant time. (It came up somewhere else, and honestly I don’t see this compiled anywhere? Writers need resources!) So you have things set in a pre-autonomous vehicle time period, or at least the only one that exists is the train and it don’t go everywhere. Your hero has two options: his own two feet, or buy a horse. What does this mean for your timeline and what sort of details do you need to know?
First things first: please do not go by Dungeons and Dragons or Pathfinder. They don’t know how horses actually work, I swear, and it’s not worth the fight to try and make their mechanics apply to your story. (Seriously had to have a convo with a DM about why a harness isn’t helpful in a riding situation. It wasn’t his fault, the entry was just written very poorly and I was like, “My inner equestrian is offended.”) They also tend to box horses into neat categories, which allow me to laugh uproariously over that. If only it were that simple.
So what do you need to know? Okay, so let’s go into some pretty broad categories and we’ll go from there. You have a general, all purpose horse. A riding horse, something bred specifically for good paces and pretty looks. Your war horses, these are trained for combat situations and usually are some ugly buggers, so be prepared. And then your cart horses, which again come in two sorts depending on how heavy your load is. Yes, there are ponies, no, unless your character is under the age of 13 or so (or has never ridden before, period), they won’t be riding them. Being mounted on an actual horse was a really big thing for the nobility, the younger the better.
(There are multiple official terms I could be floating around here, but I’ll be honest. Most are French thanks to the Norman invasion of England. If you are writing before that invasion or in almost any other country, those terms would just sound weird.)
Your general all-purpose horse is just that. It can be trained to pull a cart or buggy, it can be trained to carry a person on saddle or serve as a pack horse. Usually a combination of all three. This is what most merchants and lower owned, if they owned one at all. This horse would come up to about the chin of a grown-man, so around 15 hands or 5 feet tall. Unlike our current breed books, medieval horse breeders literally did not give a fig about colors, so they came in everything.
Now for your stupid expensive horses. A rich merchant might have nice riding horses, the nobility definitely would, but the war horses are going to be limited to those who serve in your military, whether that’s nobility or a combination of classes. Riding horses are leggy with good proportions, high spirits, and can turn on a dime. They can be the same height as a general horse, but they can also be taller, up to 18 hands, because of their legs. Warhorses, on the other hand, were stout, with lots of muscle and tended to look short in the waist and kinda awkward to watch outside of specific maneuvers. They were also remarkably calm animals, unless you threatened their rider and then all hell broke loose. Please note, these horses usually topped out at 16 hands. They weren’t tall, just strong.
So what should your horse be wearing? Believe it or not, you’re going to want to check out Western gear, it’s the closest analog we’ve got. A simple bit with headstall (no chin strap) is in line with what they wore as basics (unless you want to get fancy), and a Western saddle without a horn or quite as wide stirrup leg is more in line with what a medieval saddle tree would look like. Note, a jousting saddle would actually have an even higher front and back. They had breast collars, which I think is a very important tool because horses have slick backs. You wouldn’t see much of the fancy barding or cloth coverings outside of a joust, they just did nothing but make the horse hot.
So who is riding these horses and how fast? Having a horse at all was an expensive enterprise, but most families owned at least one because you had to get the produce to market somehow, and horses were faster than oxen (and oxen or mules weren’t always available). Please note, women would ride astride just like men. That’s why you’ll see skirts with riding slits–gaps in the fabric in the front and the back. This would let the fabric part enough to let the women sit comfortably in the saddle. The only type of side saddle that existed was basically a chair on a horse who would be led, as seen here in the Russell Crow version of Robin Hood, being used by an elderly Eleanor of Aquitaine.
As for speed, well, you have options. The fastest two are the ones you’ll use in a chase scene, because they are literally only good for short bursts. A canter or lope will run you 12-15 miles per hour, and a full-out run will get you anywhere from 20 to 30 miles an hour, it just depends on the horse. But remember, short bursts. I’m talking half a minute at a run, you’d get about two minutes max at a lope, and that’s being probably overly generous. Your best bet is to alternate the slower of the two gates, trotting and walking. A trot runs about 8-12 miles per hour, and a walk is around 4 miles per hour. Some horses have what are called ambling gaits, but they slot in with canter and trot pretty seamlessly in terms of speed, they are mostly about comfort of the rider. Assume you are going to travel about 30 to 40 miles a day.
(As a note, that’s about how often you need a small roadside inn or tavern on a road. Despite what most DnD campaigns tell you, people didn’t camp out on the road very much. Even if it’s a farm that opens its barn up to travelers, there is a place to sleep for a bit of coin somewhere without camping.)
…Hopefully my horse nerd-knowledge is helpful, I just like having it all in one blog post instead of digging through seven different Wiki articles and tumblr.