"stealthy horses in the high grass" Topic

So I asked Grok and I'm not entirely confident in the answer, so let's see what TMPers know.

The query was about modern art showing a dismounted rider and a horse lying in concealment as enemy pass nearby unaware.

The answer mention's Nolan's cavalry manual and Hannibal's Numidians.

Should I check further?

Yes, this is a real historical tactic, not just artistic license. It appears in depictions of Western (cowboy, scout, cavalry, and Plains Indian) scenes because it was an actual practiced technique in certain military and scouting contexts, especially in open grasslands where concealment mattered.
Horses can be trained to lie down on command (often called "lying down," "laying flat," or "grounding"), and well-trained ones can remain still and relatively quiet while doing so. This wasn't a universal everyday skill for every horse or rider, but it was deliberately taught in specific cavalry and scouting traditions as a way to make both rider and mount "disappear" in tall grass or low cover when enemies passed nearby. The low profile of a horse lying flat (on its side or sternum) drastically reduces its silhouette, and a calm, trained animal won't bolt or make noise if the rider stays composed.
Historical Context

Cavalry and scouting manuals from the 19th century (e.g., Nolan's System for Training Cavalry Horses, 1862) explicitly included lessons on teaching horses to lie down. This was part of broader equitation training for war horses to make them obedient under fire or for concealment.
In the American Indian Wars (including contexts like the Battle of the Little Bighorn / Greasy Grass), U.S. Cavalry horses were trained to lie down on a dismount signal. The horse then served as living cover for the trooper while both stayed hidden in prairie grass.
Similar techniques appear in other traditions: ancient Numidian cavalry (used by Hannibal) trained horses to lie flat in tall grass for scouting/ambush; some European cavalry (e.g., references to hiding from Habsburg forces) and later British scouting manuals taught it for the same reason.
Plains Indian and South American indigenous warhorses (e.g., Ranquel) were also schooled to drop flat in grasslands on command, sometimes responding to leg cues or voice so the rider could use the horse as a shield or hide while enemies rode past.
It even carried into the 20th century: some WWI cavalrymen trained horses to lie down under battle conditions for cover or calm.

Training the Horse
Horses are prey animals, so lying down makes them vulnerable—they naturally only do it when they feel completely safe. Training builds on that trust rather than force (though older "Rarey method" or rope-based techniques existed and were sometimes rougher). Modern and historical methods use progressive steps:

Start with basic cues (leg lift, bowing, or rolling encouragement on soft ground).
Reward heavily for relaxation.
Advance to full lie-down on verbal, rein, or body-language cues.

It takes time and consistency (days to months depending on the horse and method), but once learned, many horses will drop on command and stay down quietly if the handler remains calm. Noise control comes from the horse's overall training: a steady, non-panicked rider helps prevent snorting, whinnying, or movement. In tall grass, even minor sounds are muffled, and the visual camouflage is the main point.
In short, the scenes you see in Western art (think dramatic prairie hide-and-seek moments in Remington-style paintings or later cowboy art) reflect real horsemanship from the cavalry/scout era. It's not common today outside specialized training or demonstrations, but the skill is still taught and demonstrated by some horsemen. Horses aren't machines, so perfect silence isn't guaranteed every time—but a solid partnership makes the tactic work well enough to fool passersby in the right terrain.

ChatGPT had more on Nolan. Oh yeah, THAT Nolan:

he work is usually cited as:

Nolan's System for Training Cavalry Horses (1862)

The historical chain is slightly confusing because:

the original ideas came from Louis Nolan, the famous cavalry theorist killed in the Charge of the Light Brigade,
but the American edition/adaptation was edited and expanded by Kenner Garrard during the American Civil War.

And yes — remarkably — it does include instructions for teaching horses to kneel and lie down.

The manual actually discusses:

kneeling,
lying down,
sitting up on the haunches,
even walking on the knees.

But there is an important caveat.

Nolan/Garrard themselves regarded much of this as:

specialized,
somewhat degrading,
closer to "performance" training than battlefield necessity.

The text explicitly says, in effect, "I publish this reluctantly." It describes the process as hard on both horse and trainer.

So your instincts are correct:

this was known in 19th-century cavalry circles,
it was sufficiently established to appear in a military horsemanship manual,
but it was not ordinary line-cavalry doctrine in the sense of "every trooper trains this weekly."

Rather, it sat on the edge between:

advanced horsemanship,
trick training,
practical field utility,
and exhibition riding.

What was militarily relevant was the broader principle Nolan strongly emphasized:

individual horse control,
responsiveness,
flexibility,
and using cavalry dismounted when appropriate.

That fits very well with Nolan's broader reputation as a reformer. He admired highly skilled irregular cavalry traditions — including Cossacks and other light cavalry systems — and pushed British cavalry away from rigid parade-ground habits.

So while the "horse lying hidden in ambush" image may sometimes be romanticized in art, the underlying skill itself was absolutely real and documented in period military literature.