Horses were an absolutely essential — indeed defining — component of a knight’s equipment. The German word for knight (ritter) derives directly from the word for rider (reiter), while the French and Spanish terms, chevalier and caballero, derive from the word for horse (cheval and caballo respectively). While a knight might temporarily be without a mount, without a horse a knight could not fulfill his fundamental function as a cavalryman. Indeed, the symbol of knighthood was not the sword (infantrymen had those as well) or even the lance (they were throw away pieces of equipment), but the (golden) spurs tied to a knight's heels during the dubbing ceremony. Richard Barber notes in his seminal work The Knight and Chivalry that being financially in a position to outfit oneself with arms and horses was crucial to knightly status. David Edge and John Miles Paddock argue in their comprehensive work Arms and Armour of the Medieval Knight that “[a knight’s horse] was the most effective and significant weapon the knight had; the basis of his pre-eminent position in society and on the battlefield.”
In short, knights needed horses — significantly not just one horse but several. This short post provides a overview of a knight's equine needs.
The warhorse or destrier, is the most obvious of a knight’s horses. This was the horse a knight rode into battle, joust or tournament. This horse was his fighting platform. It was trained to endure the shock and noise of combat. In later years, destriers were sometimes also trained to lash out at enemies with teeth and hooves thereby becoming, as Edge and Paddock note, a weapon as well as a fighting platform. Knights rode stallions, not mares or geldings. This was in part because stallions were considered more aggressive, but also because riding a mare or a gelding detracted from a knight’s image as a virile warrior.
Destriers were not a specific breed of horse, so arguably the defining characteristic of a destrier was simply its function — and price. If a knight thought a horse had what it took to be a fine destrier, he was willing to pay a large premium for that — and anyone in possession of a horse with the necessary qualities was going to ask a commensurate price for it as well. In short, destriers were outrageously expensive. They cost 4 to 8 times the price of lesser or ordinary horses. They cost as much as the armor a knight wore. They could cost as much as the annual knight’s fee — in short roughly the annual income of the gentry. The equivalent is the price of a top-line a BMW or Mercedes today.
Like any horse, destriers were vulnerable to colic and injury, however, which meant a knight was well advised to have more than one of them— if he could afford it. Even if he could and did, however, he was likely to have a favorite. The destriers of knights in contemporary romance and legend all have names: Baucent, Folatise, Babieca etc., but perhaps no description is more famous that the Dauphin’s praise for his horse before Agincourt in Shakespeare’s Henry V. “When I bestride him, I soar, I am a hawk: he trots on air; the earth sings when he touches it…. It is a beast for Perseus: he is pure air and fire….”
For all their value and importance, however, a knight spent far less time mounted on his prized destrier than on his palfrey(s). Palfreys were riding horses, transportation not weapons, the means of getting from point A to point B. Since medieval knights rode everywhere -- to oversea their estates, to visit neighbors, when hunting or hawking, to attend court or to go courting. In short, a knight spent literally countless hours with his palfrey(s). Palfreys were bred not for strength and fierceness but for smooth gates, endurance and common sense. They were probably much the same size as destriers, but lighter — marathon runners rather than sprinters, wrestlers more than boxers.
Since these horses were just as likely to get colic or injured, the need for more than one palfrey was just as compelling as with destriers, but given the substantially lower price of palfreys the possession of more than one was considerably more common. Knights would normally have possessed at least two and wealthy nobles likely had stables of horses at their disposal for transport purposes.