Having found yourself in a war...

Become a fighter pilot. Fly around, shoot down unarmed bombers.
No, I'm serious.

What's the difference between civilian and military targets? They're both people... Besides, you'll have to carry out bombing raids on someone's orders. A simple soldier isn't responsible for that. And if, to achieve success, it's necessary to bomb, for example, a large railway junction, and there are civilians nearby, then the pilot is probably not to blame (his goal is not to kill civilians, but to disable the object), but first of all, the enemy, who did not evacuate the civilian population to a safe distance from the front line, and the civilian population itself should stay away from possible enemy bombing targets...