How to have a fantasy kingdom fight the US Armed Forces?

[Alane1]

That would indeed very much a setting dependent thing, many settings have different rules on what works and doesn't work.

One setting might only require faith including the faithful reciting religious text as well as things like holy objects and water, some might require people divinely blessed, while others might require complex rituals to summon or get rid of, or the demons might just suffer certain restrictions on what they can or can't do.

Or there are doom demons/Wolfenstein demons which apparently can just be shot repeatedly with heavy fire power if you're the protagonist while the rest of the arm forces get slaughtered and turned into zombie minions.

 

[Mak Taru]

As for fantasy settings that fit the OP, what about Warcraft? It started as a series of RTS games, so armies and no-name soldiers are an important part of warfare. Although with WoW and stuff that may have gone out the window somewhat.

 

[Frumple]

It'd be interesting, maybe? I have no clue what the state of the world is like with WoW factored in, though... there was a point I was fairly on top of the lore and whatnot and that ended hard after WC3, heh.

... just with WC3, though, it's another one of those where there'd probably be an initial shock (... maybe, considering accurate divination and straight up time travel are entirely on the board) and then the modern military gets its teeth kicked in. It wouldn't be the first time the setting has given the boot to an interdimensonal invasion force, or dealt with... basically everything a modern military can throw at them. It's already a setting that has fairly developed firearms and artillery, all the military vehicle sorts including battleships, bombers, submarines, tanks (and having to deal with goddamn elves running around with bows capable of shooting through a friggin' ironclad or some crap), various citykillers, and so on. Plus there's some wildly scary crap in there, like the literally magical continent spanning undead plague and junk.

Armies and no-name soldiers are indeed important, but they're armies and no-name soldiers that cut their teeth on some really nasty stuff and overall are probably pretty superhuman as a baseline. Going by base mechanics, your average human footsoldier, barely trained and one of the weakest dedicated melee combatants, would probably be capable of fairly rapidly stabbing through tank armor with a friggin' longsword. So could ghouls literally bare handed. It'd be a weird matchup, but I'd bet on the massive physiological disparity, experience with an interdimensional, possibly existential, threat, already fairly existent exposure to only slightly off parity technology, and, well... all the magic on top of it

Warcraft isn't a particularly low power fantasy setting, heh.