I also heard in some recent news article that horses can sense your attitude or fear etc. I can't recall exactly. But I would think they pick up on your fear and that sets them on high alert. And what rider can be calm and controlled during a major battle???
There is another problem that I experienced on a Shetland pony we kept for awhile. It was an old pony and you had to be deliberate to get it to ride to the opposite end of the pasture. Once you turned his nose back in the opposite direction you better hang on. He bolted for the barn while taking every corner so close that you knew your leg would be ripped open by a barbed wire. Wonder if this was a problem in the Army? They didn't actually have a barn in the field but was there a problem of a horse getting fed up with the confusion and headed back towards home or to join the other pack?
And I thought this discussion was going to be about how big of a Target a horse was on the battlefield.
I don't know about a magazine article, but the first thing I was ever told at a young age was they could sense fear.
As for the subject, it seems to be one of horses shouldn't be on a battlefield because they are such dangerous animals.
But horses had to be on battlefields back then, literally no choice. Horses were needed to haul the artillery, ambulances for the wounded, ammunition trains, and outside of a battlefield supply trains. As for cavalry they were an absolute necessity for scouting, and faster than foot movement to key positions on the battlefield. Great big cavalry charges, not so much...
Horses were a desperately needed thing, infantrymen had all they're own stuff to carry on their person much less pull a wagon, or cannon after all, and couldn't move fast enough in the middle of a battle to get to a key position and defend it on their own. They needed cavalry to get there first and hold it for them, and cavalry to find a flank.
Yeah horses have a mind of their own, and tragic accidents could happen on and off the battlefield, but that is the nature of the beast you just got to/had to live with it. At that time they were among the most needed on the battlefield, not the last thing that should be on it, and far from the most dangerous thing.