Why not make a more realistic post concerning the past of our world, take the bombings of Hiroshima and Nagasaki for example.
Lets pretend you have only one choice here, drop the atom bombs, which will kill thousand upon thousands of civilians, reduce the surrounding area in dangerous territory for years to come to save some Soldier lives or keep on attacking those, who you basically bullied into joining the war and attacking you in the first place, just to satisfy your hunger for war.
So anyway back to the question at hand, if that were the only options I would weight the "usefullness" of the soldiers agaisnt the civilians, sorry if that sounds harsh, but seeing how people honestly would kill innocents, whose only fault was to life there, to save some sorry assholes, who will probably die the next day anyway, than I see something seriously wrong here.
If those soldiers aren't crucial to the war or won't be able to end the war without much more bloodshed than go ahead, let them die. They came into this war and they made a mistake, thus they need to flee, let them go down in a heros death, but as soon as you trade a civilian life for just one soldier life you are walking a slippery slope.
Because who says this will breaks anyones moral..you know what will happen, retaliation, if you start to kill civilians than say good bye to all your POW's, because they will be executed as well as sparking new breath into those who you unjustified attacked.