You've brought up an important point that seriously complicates the idea of civilian immunity: what the heck can you do when the enemy essentially conflates the civilian population with the military?
This is an ever-present factor in Iraq: the fact that the murderous thug factions all use homes, hotels, schools and places of worship as arms caches, recruiting, training, and logistical-support areas, as well as launching attacks from and within residential neighborhoods, always using the whole surrounding non-combatant population as--- in effect --- "human shields."
That certainly makes the thugs, themselves, directly morally responsible for the collateral casualties.
I don't think that completely obviates any responsibility to try to protect noncombatants, or to avoid objectively indiscriminate destruction. I do keep in mind that Eisenhower and Leahy were opposed to using the bomb (Eisenhower personally argued with Truman about it). Leahy said it and using other WMD such as germ bombs, was unbefitting a civilized country), and no less a personage than Curtis "Bomb them Back to the Stone Age" LeMay said the bomb was unnecessary to force Japan to surrender. MacArthur agreed the act was unnecessary.
They knew the war was over.
I don't regard them all as being "extremely ignorant."
Hm?
Yes, but Eisenhower's concern was about whether the a-bomb would work. Ike had seen a lot of experimental weapons in the European theater, he had seen a lot of them fail or not achieve their strategic objective, the "Dambusters" comes to mind. Eisenhower was afraid that the a-bomb would be a dud, or not as effective as it was.
and no less a personage than Curtis "Bomb them Back to the Stone Age" LeMay said the bomb was unnecessary to force Japan to surrender. MacArthur agreed the act was unnecessary.
You are taking the quotes to support your position out of the context in which they were said. I know the context and MacArthur and LeMay did not condemn using the bomb to shorten the war and achieve an "unconditional surrender".
I don't think that completely obviates any responsibility to try to protect noncombatants, or to avoid objectively indiscriminate destruction.
That statement tells me that you have little actual knowledge of how the military thinks or is run.
By the way, are you aware that Churchill was prepared to use mustard gas on the Germans should they invade England? The gas masks that the British authorities passed out to the general population in 1940 was not to protect the civilians from German gas, but British. Was Churchill "uncivilized"? I think not. Quite the contrary, he knew that the civilized must become as savage as their enemy in order to survive and in surviving, return to being civilized. Such was the genius of leaders like Churchill.
Would Churchill have bombed Hiroshima and Nagasaki? I think not, he would have bombed Tokyo and Moscow and he would have been right.