Can Only War be made to work in a pre-industrial fantasy setting?

Some of my buddies saw an old Civ thread about the "Unwashed crusade", and what started off as a joke of wanting to play characters in it has turned into a pretty serious movement.

The high lethality, slap another character in when the old one dies, and the fact that FFH seems to borrow quite a bit from 40k stylistically made me think of OW, but of course, this is a war being fought with spears and swords and divine magic.