You know what the movies say, as did the books before them. The armored knight's horse was his transportation into battle, a heavy draft horse capable of carrying the armored knight.
Not quite.
First of all, the trained warhorse was not a Morgan horse or any other heavily-built equine. There are several reasons to believe that modern writers got it all wrong.
The need for a heavy horse presumes that the knight weighed as much as the movies show. Connecticut Yankee in King Arthur's Court and Disney's Sword in the Stone show the armored knight being lifted into his saddle by block and pulley. It followed that a heavy draft horse was needed as a mount.
Forget it. The armor weighed 70 pounds, which is pretty consistent throughout history, from Greek hoplite to modern soldier. A heavy draft horse was not required.
Also, the heavy breed horses presented problems. They were specifically bred for farming. As a result, they were too placid for combat. They lacked the maneuverability or speed of smaller breeds.
In addition, there are numerous examples of armor for horses that fitted over the head, across the top, forehead to nose. Absolutely none of them will fit a heavy draft horse. They all fit horses of fairly normal size.
There are also records of how many hands high a warhorse is and the measurements are prefectly consistent with a normal size horse, not a heavy breed.
Second, the trained warhorse was the knight's most formidable weapon.
In response to signals, such as how the spurs would be used, the horse could kick out in front, trampling an infantrymen. Visualize a half-ton of horse coming down on you from above.
The horse could also be directed to kick out behind, and even continue kicking while shifting position so as to shift aim. There's even a maneuver practiced by the Lippazaner Stallions of Vienna which was in common use among horses used in medieval combat, where the horse could leap upward and kick out with all four hooves at enemy troops.
Keep in mind that heavy cavalry was not used against enemy cavalry. It was targeted at the weakest part of the attacking army. This would be ground troops made up of untrained or lightly-trained, unblooded farmers and tradesmen. Very inclined to stampede with an aggressive attack with a formidable weapon.


Comments: 11
Good points but the desteriers or warhorses were big. Knight's armor as you pointed out was lighter than Hollywood usually thinks BUT the workhorse as we know it today descended from them. Horses were too valuable to use for farming and oxen were cheaper and tougher. Generally knights rode lighter horses out of armor until contact was more likely, sargeants (more lightly armored men, not NCOs as we know it) or other lightly armored cavalry screened the knights until then. Picture cavalry or mech infantry as the screen with the knights making up the heavy armor