If in some war there are a lot of civil victims, it means that either the army was hiding among their own civilians (what is equal war crimes for me) or that the enemy army was particularly aiming civilians that is the war crime again.

Also, there can be situations when somebody is particularly aiming on civilians and it does not result in so many casualties. Some examples of that you can see in ex Yugoslavia which built numerous atomic shelters underground (I lived in a 'town' of 20k including all the surrounding which had 11 completely equipped atomic shelters). For decades during Yugoslavia, there was an exercise practiced in spring that was called 'Nothing can surprise us'. They would turn the sirens on and people would go to the nearest shelter. The idea was to teach people during the peace where those shelters are, how they function and to practice quick evacuation.