Every Heavy Cavalryman Would Need Several Horses

The culmination of selective breeding was the destrier, the “great horse” or warhorse which by the late Middle Ages could reach eighteen hands in size and astonishing prices. The warhorse was suited for combat and was the symbol of the aristocracy; its value and rarity meant that not too many soldiers could afford one. Most soldiers seem to have ridden more humble animals, or rounceys. The use of a different horse may have been dictated by other reasons. For instance, the favorite English horse in the chevauchées in France during the Hundred Years War was the courser, which combined stamina and mobility. In reality every heavy cavalryman would need several horses: the warhorse, which the knight’s squire would lead with his right hand, a more modest horse for the squire himself, and a horse to carry the knight’s armor to the battlefield. It was only when confrontation became inevitable that the knight would wear his armor and ride his warhorse into battle.

— Barbarians, Marauders, and Infidels, p. 132

Emphasis mine.