to or toward
d. " the soldiers fought hard and many died. "
from how i read it, this seems correct.
the last two lines of the passage, "then they rode back, but not. not the six hundred.", leads me to think that the answer is possibly d. now, b would more than likely be incorrect, because if thought about, whenever guns tend to fire, (well, i'm assuming that's what they were smoke ends to get into the air, due to the gunpowder being shot out rather quick. they could've been using other weapons, buuut i'll save some time and not go through explaining that.. besides, it seems a tad bit pointless to burn a battlefield, i mean, what's the use-?
anyway, let me get back to the point. this seems like a battle between two separate sides, and soldiers ended up dying by the enemies in this, from how it's being explained.
so, conclusion, your answer would most likely be d.
( i'm not too good with explaining things like this, and i got slightly confused while reading this, but hopefully i - ^^; )