Got it! While breed registries and organizations around the world began forming in the 1700 and 1800's, I'm willing to put money on that these horses are bay and specifically one of Britain's oldest breeds the Cleveland Bay and perhaps the Hackney Horse. The Cleveland Bay must be bay or he can't be registered and the Hackney Horse is primarily bay.
But I didn't base it solely on that. I found this website:
British Cavalry: Napoleonistyka
Scroll down 3/4's of the way through the page - there's a quote you might want to look at in regard to those black horses:
The men of the Life Guards were mounted
on large, black horses with manes brushed
to the left to distinguish them from
the Royal Horse Guards (The Blues')
who brushed them to the right.
But aside from that here's the actual information:
The splendid English horses.
"The luxurious attentions which are lavished upon them,
render them quite unfit to support fatigue,
scarcity of food, or the exposure of the bivouac.
The men, however, are excellent grooms."
- French General Foy
The British and German horses, whose tails were docked in accordance with British practice,
Docked tails meant one thing - carriage horse, draft, or other working breed for pulling - the tails were docked to keep them out of the way. The Cleveland Bay is a carriage horse and the Germans imported it like crazy to cross with their own horses. The Hackney Horse is also a carriage breed and sported a docked tail
And I'm snipping irrelevant stuff out for space....at least in regard to horses.
In 1815 (Waterloo Campaign) the French cavalry was impoverished and had considerably scaled back the strength of cavalry regiments. By contrast England had always good horses and the financial means to obtain more of them wherever they might be found.
French General Maximilien-Sebastien Foy wrote: "The pains bestowed by the English on their horses, and the superior qualities of their native breeds, at first gave a more favourable idea of their cavalry than the experience of war has justified. The horses are badly trained for fighting. They have narrow shoulders and a hard mouth and neither know how to turn or to halt. Cropping their tails is a serious inconvenience in hot climates. The luxurious attentions which are lavished upon them, render them quite unfit to support fatigue, scarcity of food, or the exposure of the bivouac. The men, however, are excellent grooms."
This is the epitome of a period carriage horse, especially in regard to nobility. Ride to the park on a Sunday afternoon, go to a party on one night...and so on...short runs then stabled and pampered.
However, in the beginning of Peninsular campaign the lack of experience cost the British cavalry many excellent horses. “The tragic end of Lord Paget’s heroic cavalry chargers is made even more shameful when one considers the verdict of William Napier: '‘The very fact of their being so foundered was one of the results of inexperience; the cavalry had come out to Corunna without proper equipments, the horses were ruined, not for want of shoes, but want of hammers and nails to put them on !” (Summerville - “March of Death” p 177)
Founder is actually an illness caused by feeding improperly. If a horse goes without food (as it sounds like these did) then suddenly achieves food and is allowed to gorge, it can founder. The same thing can happen with modern horses in a pasture when the spring grass comes in. It's so high in sugar and they gobble it down because it tastes good. Then they founder because of it. Without going into the gory details, founder is very painful and the bone in the horse's hooves can rotate, even punch through the bottom of the hoof. Basically founder was a death sentence, especially back then and especially because they didn't have the veterinary medicine to know what caused it.
While this doesn't specifically say the breeds that I have found, I'm almost postitive by what you've described and knowing what breeds the Brits had back then, plus what I've read here, you're looking at the Cleveland Bay and perhaps the Hackney Horse. Understand too because the breeds were being formed then - they would have looked nothing like what they do today. So when you go to this next website and see pictures of that high stepping horse don't think NO WAY! The horse didn't have that action back then - it was bred into them...probably starting back then and took generations to achieve.
Here's more info for you:
Hackney Horse
Cleveland Bay
There are other horses on that site as well, Anglo-Arab, Thoroughbred (they may have docked tails as well but I'm not sure as I didn't get that far into the research. I'll leave that to you!
But if you need help, let me know.
I hope this helps! Good luck on your project!
Cheers,
Karrie