Agreed- generally trying to create the Enlisted Man is a bad business no matter who or what you're doing it for. That said- no empire was ever created bloodlessly, so it could definitely add some interesting roleplay opportunities for PCs as they discover how it all was done or try to justify what was done and in whose name. Maybe they'll have to deal with the aftermath, if the soldiers are meant as a one-off use and to be mopped up after the war is over- or figuring out what to do with a bunch of brainwashed soldiers when some of them don't stay brainwashed or start asking the big questions like any other child whose curiosity grows beyond what they were encoded with at birth.

I'm curious as to the answer to the original poster's question, as I've envisioned a Sauruman-style origin for a race in my homebrew setting, and it would be really cool to know which spells specifically the mages of the Ancient Sorcerous Empire (tm) would need to devote themselves to for that kind of production-scale.