The Charge Of the Light Brigade

I think that this poem is about a fleet of troops who put them selves in harms way by charging in an alley were they know that they are going to die. I say that they know that they are going to die here because they refer to this alley as the alley of death and is repeated many times. I think they decide to do this because it is there only sign of hope. Now once they get in the alley they are ambushed by canons by almost all sides and are being quickly killed.