First time posting, so forgive me if I did this wrong or it's a bad question. I watch a lot of shows that are based in a medieval or fantasy settings with knights and warriors riding on horseback. I don't think I've ever seen foot soldiers ever targeting the horses instead of the riders. I don't know if it's because of filiming it, so you don't hurt the animals, or if nobody actually did that. I'm thinking that they would aim for the rider so they could steal the horses or something. Is there a definite answer though?
Yes. Many people aimed for the horses instead of the riders.
Roman writer Vegetius wrote this in his text on Roman warfare:
The armed chariots used in war by Antiochus and Mithridates at first terrified the Romans, but they afterwards made a jest of them. As a chariot of this sort does not always meet with plain and level ground, the least obstruction stops it. And if one of the horses be either killed or wounded, it falls into the enemy's hands. The Roman soldiers rendered them useless chiefly by the following contrivance: at the instant the engagement began, they strewed the field of battle with caltrops, and the horses that drew the chariots, running full speed on them, were infallibly destroyed. A caltrop is a device composed of four spikes or points arranged so that in whatever manner it is thrown on the ground, it rests on three and presents the fourth upright
Basically, the Romans would little the field with small spikes that would break the hooves of the horses. The horses would fall down when they stepped on them, the charioteers would fall out, and the Romans would kill them and take their chariots.
Here we see a spike horse bit (the thing that goes in their mouth). These bits were fairly common, and they existed primarily to keep the enemy from grabbing the horse by the bit and pulling it down or out, thereby removing the rider's ability to control the horse. Here is a picture of just the bit.
Spear equipped infantry would almost always aim for the horse- it just makes more sense to do so. This is why horse armor existed- if it wasn't common or likely, people would not have spent marge sums of money to armor a horse.
Even in Xenophon's text, On Horsemanship (the first book on riding that we have, from about 400BC), talks about way to protect the horse from enemy attacks.
Anyway. Your question was more directly focused on the Middle Ages... yes. Medieval armies still used and carried caltrops. They also used spears, and would use spears against horses at pretty much any given opportunity.
Sometimes, like in the battle of Chaumont in 1098, apparently William II lost some 700 horses to archers who were told specifically to shoot for the horses.
So, yes, in Medieval combat, losing your horse to warfare was very common.
Now, sometimes it did make sense to only kill the rider to seize the horse, but taking horses as prizes usually was only a concern after the battle. During a battle, where your life was at risk, your priority would be to kill your attack and not to take a prize.
