A little bit of History:
Humans have used for millennia to horses for war, probably since their domestication. The horse has been specially trained in various military applications, including battles, single combats, reconnaissance, transport and supply. The workhorse term refers to horses are used for fighting, either as cavalry in a battle or in single combat. The horse was the best known battle destrier employed by the knights of the Middle Ages. However, even the horses used for other purposes other than direct combat had a significant role in the success of military engagements paper. In the modern world, there are still uses for horses within the military.