"The majority of the head wounds were believed to have been caused by shell and grenade fragments." So two possibilities might be that bullet wounds to the hea

"The majority of the head wounds were believed to have been caused by shell and grenade fragments." So two possibilities might be that bullet wounds to the head would be more often fatal or that most deaths and wounds come from artillery and grenades. I think that the later is the case and that a soldier's probability of survival is mostly a combination of skill in maintaining cover and luck.