Today, I did four miles, in an hour, I'm doing intervals, running pretty hard and then walking. It's slowly coming back.
Jackson's "Foot Cavalry" in the Civil War would do 4 miles in an hour, and then rest ten minutes, and do it again.
All day. Often barefoot. Carrying probably 20 pounds of rifle and ammo and water. Poorly fed. And then do it again the next day. It's a killing pace for a horse not in good shape.
I briefly knew a lady who did long distance horse riding events, 100 miles. She said she walked the horse about as often as she rode. Every 20 miles there was a stop to take the horse's temperature and if it was over X, your were DQd. I asked if they took her temperature and she laughed. A human can outrun almost any other mammal, I'm talking a human in top condition versus an animal in top condtion, there is a western antelope that can sustain some ridiculous pace for hours. In a day, a human can outdistance a horse.