We all know the epic and brutal picture movies depicts when it comes to medieval and ancient wars
But the reality was different. Most of the times, there was no big charge army against army, no free for all where everybody was running around on the field dishing sword hits to everybody (in the heat of the battle, covered in mud, it would have been hard to recognize who is who...)
Most of the battles were in tight formations, and as soon as one camp started to look morale, they'd flee.
Average casualty rate for pre-industrial war was only 5%-6% for all sides according to some historiansand most of that happened after the losing side started to flee (so killing retreating or surrending folks)
Compare this to casualties registered for WW1:
So which type of war front was really the gulliest? Modern ones (after the industrial revolution) or the ones before that? In which type would you rather get caught?
the way to kill people with modern weapons will blow your mind, and your forgetting the big one, nuclear weapons. That being said look at the mongol conquests and Taiping Rebellion for body counts
and most of that happened after the losing side started to flee (so killing retreating or surrending folks)