There actually is some precedent for a Total War type experience in AD&D. First off, D&D itself started as an offshoot from miniatures combat (Chainmail, etc.) so it was a natural attraction for the gamers & designers. The closest that AD&D got was the Battle System combat series from the late 1980s, which unfortunately got shut down when the 2nd edition books came out. But using that I fought gigantic battles with thousands of troops against wizards & dragons in an AD&D setting. (yes, I'm an old fart) Granted it's not the stereotypical thing one thinks of in D&D but it was definitely there at one point. There's nothing quite as entertaining as the vision of a Blade Barrier under a Telekinesis spell working its way through a horde of orc troops. Whirrrrrrrr!