Horses have played a role in military application throughout all recorded history. Horses have been instrumental for fighting men and women in a variety of uses, from convoys for hauling gear to cavalry engagement, reconnaissance, and navigating difficult terrain. The speed and mobility of these animals have allowed soldiers to quickly respond to changing battlefield conditions throughout the history of warfare. Horses on the battlefield also provide a psychological impact. Overwhelming cavalry charges can be intimidating and demoralizing to the enemy just as much as the horse’s companionship can boost the morale of troops and give them an immediate, tangible purpose to continue fighting. The combination of speed, mobility, psychological impact, and reliable transportation that horses provide has contributed greatly to the horse/human relationship. The historical partnership between fighting men and women and their service equines may inform some aspects of the relationship between horses and veterans who seek equine therapy for PTSD and other service-related mental health issues.