The quintessential knight is rarely a solo character; indeed, he is generally depicted riding his great steed.

“David defeats the Philistines.” Used with permission. Via http://www.medievaltymes.com/courtyard/images/maciejowski/leaf30/otm30vb.gif
Horses in the Middle Ages were not like the genetic breeds we have today, instead they were characterized by their physical attributes or what they were used for (“Horses in the Middle Ages”). The main types of horses used by knights in war were the destrier, courser, and rouncy. Destriers, large and strong horses, and the lighter coursers, were favored for use in battle (Prestwich, Knight, 45). Poorer knights, squires, and men-at-arms would use the rouncey, an all-purpose horse used for riding, battle, or as pack horses (“Horses in the Middle Ages”).
The horse was likely the most expensive piece of equipment in the knight’s inventory (Prestwich, “Miles”, 212). Prices of horses ranged considerably; Prestwich suggests that the value of a horse may have been determined by more than quality, the social rank and wealth of the owner may have also contributed to the value (“Miles”, 211). Generally, destriers tended to be more expensive than other horses – one estimate is seven times that of a normal horse (“Horses in the Middle Ages”).
Knights were skilled at fighting on the ground as well as on their mounts, and their tactics varied depending on time and the situation. Sidnell suggests that knights would dismount to boost the morale of the infantrymen, as well as when the terrain made riding ineffective (321). When mounted, the horses would sometimes fight each other, and destriers might have been trained to bite and kick their enemies. This may be due to the fact that stallions were most commonly used as war horses in Europe (“Horses in the Middle Ages”).
The armor worn by horses was called barding, and it consisted of many pieces. Depending on the time and cost of material, the various pieces of barding would be made of plates, chainmail, or leather worn over a layer of padding. Often, the armor would be covered with stretches of cloth called caparisons (“Barding”), pattered with the insignia of the knight to distinguish them in battle (Prestwich, Knight, 46).
In battle, horses needed to be obedient and maneuverable, so training was very important (“History of Dressage”). Tournaments were used for training the horses to get used to the noise and frenzy of battle (“Horses in the Middle Ages”).
Works Cited
“David defeats the Philistines.” Maciejowski Bible. The Morgan Library & Museum, New York. Medieval Tymes. Web. 5 Apr. 2012.
“History of Dressage.” United States Dressage Federation. n.p, n.d. Web. 5 Apr. 2012.
Prestwich, Michael. Knight: The Medieval Warrior’s Unofficial Manual. London: Thames & Hudson, 2010. Print
Prestwich, Michael. “Miles in Armis Strenuus: The Knight at War.” Transactions of the Royal Historical Society 5 (1995): 201-220. Print.
Sidnell, Philip. Warhorse: Cavalry in Ancient Warfare. London: Hambledon Continuum, 2006. Print.
Wikipedia contributors. “Barding.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 30 Mar. 2012. Web. 5 Apr. 2012.
Wikipedia contributors. “Horses in the Middle Ages.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 5 Apr. 2012. Web. 5 Apr. 2012.