What was a medieval war horse called?

Answer 1

Mediaeval war horses were what are now known as Shire horses- massive breeds of horse renowned for their strength, size and power. They had to be like this to have the strength and stamina to carry the weight of a cavalryman or knight in full battle-armour and his weapons (as well as their own armour and military colours) into battle at full charge, and to withstand the effort of long, tiring bouts of combat in the field. When heavy mounted combat of this sort was succeeded in the 17th Century, Shire horses became used mainly as draught animals and as heavy working horses- to find out more about them, just Google 'Shire horses' and refer to one of the sites indicated.

Answer 2

The medieval war horse of a knight or higher was called a 'destrier'