The Battle of Shanghai is the sort of big, fat chunk of history that somehow gets lost in the fury of the years just before the start of WW2. I learned about it doing research for my novel.
But for all its pulp trappings and Chinese fantasy elements, what I’m writing is still a historical fantasy.
To me, historical fantasy means that history as we know it stays in place, but fantasy happens in the dark corners and hollow places that history books don’t cover.
I can’t change the course of events and still call it historical fantasy – it can be pseudo-historical fantasy, it can become a form of uchronia*, but historical fantasy it can’t be anymore.