Yep, a Knight would get up on his “high horse” and ride over other cavalry. Those suckers were like Clydesdale's, but mean!
Still, the Middle Ages War Horses were definitely what folks had been after for a very long time.
BTW, this business about modern horses being large enough to ride has misled folks about how the horse was domesticated.
The earlier idea was that early man saw that horses were rideable and started out riding them bareback. Fact was they were edible, not rideable, and they were fit only for pulling light built wagons called "chariots". Good shot of King Tut's chariot at http://news.discovery.com/archaeology/king-tuts-chariot-heads-to-new-york.html
Gives a very good idea of what "light" meant in the early days. That one's for two horses BTW. Even the Pharoah couldn't get a really big horse.
For a thread that gets right to the heart of the problem of taking a moderate sized animal and breeding it up to where it’s among the other animals, try this thread: http://www.freerepublic.com/focus/f-chat/2598013/posts
So the knights had to be expert mahouts, too?