It's spot on. I know the guys. The lake they are doing training in at the beginning, literally been there and done that. The battle of horses vs. tanks actually happened, although when they told me, I couldn't believe it. It's just - well it's silly sounding. But the tanks were old and poorly maintained, the crews poorly trained, and the horses could literally run circles around the tanks faster than the turrets could turn. And fighting with tanks the way they did plays on their weaknesses, not their obvious strengths.
If you like to believe that things happen for a reason, I was most well known and liked by this team; if my son had not lost an eye, I am very confident I'd have been with them. Perhaps I'd not have been as fortunate as they. I served under the general they show in the beginning, selecting the team. My wife met him years later and he gave her a coin, it's a thing in the US that senior military people do. The team sergeant in the film is the guy who took the iconic photos of the horse soldiers:

The wincing man is wincing because his back is broken. Tough stuff.