Is killing innocents ever acceptable as "collateral damage" in war?

if the deaths of a few civilians saves the lives of hundreds of thousands of men then that's a price I'm willing to pay. For example, the atomic bombings. If those civilians didnt die that would have ment the war would of had to carry on and millions of more people would have died. However, any other situation the killing of innocent people is horrible and should be punished by worse than death.