Ah, yes... I understand this extremely well. Trouble is this: the battle scene ends with a disaster which sets in motion the story, so it might be really hard to hook the reader without revealing too much They could be fighting for anything, that's not important.
I could use a motto or a quote at the beginning, to hint at what's coming, because the battle would stretch on a couple of pages and we don't want the reader to get bored before he reaches disaster part... At least that's how I see it.
I think perhaps we should give readers some credit. They don't all give up on a book they've chosen to read if they actually have to go more than a page or so with a big payoff.