>>509943486
The majority of deaths in warfare in ancient times weren't actually combat-related. They were mostly disease and fatigue related. They would spend like 90% of their time camping in a nearby position and then only spend a total of 48 hours fighting at most. Compare that to soldiers starting with WW1 being kept up 24/7 by the vibrations of bombardments, which caused nerve damage. Modern transport also meant you would be much more mobile and that means less mental breaks between engagements.