The riders are superb. The lacework, shading of the overalls and the water bottles, for example, show great attention to detail. A suggestion, the open mouthed officer would be transformed by a tiny off white line across his upper mouth. Top teeth will show when shouting like this and adds immeasurably.
Herkeybird's comment about the horses. Greys are a huge challenge anyway. Get close enough and you will see that, unless ready for the knacker's yard, greys are really white with varying proportions of black hair. The painter has provided a nice variety and the camera probably does exaggerate the contrast. I'll bet, naked eye, the effect is far better.
I would try to achieve just what we see here, but then tone it down with repeated washes of very dilute white. The dapples are never uniform unless on toy rocking horses. Start big (end of cocktail stick) but wider spaced, as you work down the horse make them closer together and slightly smaller, till solid white. Works for me. I would only really criticise the eyes personally. Almost, almost, no white in a horses eye. The pupil and central black iris almost fills the eye socket between the lids anyway.
Terrific painting. I like the simple base as well. I have been overdoing it so far………….too much foliage and detail!