There really is a difference between a mistake in the fog and dark and using an ambulance to transport explosives.
Yes, it is moraly worse to target civilians than to target combatants and kill civilians in the process.
Worst of all is to deliberately place your civilians in harm's way as SOP. It shows that you think your enemy cares more about your people than you do. If you even consider that it is possible for your enemy to care more about your people than you do, and you do not step down, you are no leader, just a thug.