In medieval times, what was a palfrey?

A palfrey is a type of horse that was highly valued as a riding horse in the Middle Ages. It was a lighter-weight horse, usually a smooth gaited one that could amble, suitable for riding over long distances. Palfreys were not a specific breed as horse breeds are understood today.

The significant characteristic of the palfrey was that, rather than trotting, it usually possessed a smooth, ambling gait. The amble was the name given to a group of smooth, four-beat gaits faster than a walk, but slower than a canter or gallop. The trot is a two-beat gait, about 8 mph, suitable for covering a lot of ground relatively quickly.

However, the horse also has a bit of a spring in its motion as it switches diagonal pairs of legs with each beat, and thus can be rough for a rider, and the trot also jostles about packs or weaponry to a considerable degree. The amble is about as fast as the trot, not tiring for a horse that performs it naturally, and much smoother for the rider. Thus, because much ground transportation in the Middle Ages was on horseback, with long distances to be covered, a smooth-gaited horse was much desired.