While I have no doubt that it leaves marks and experience, it seems you don't get my point. What I'm saying is that in battles where it's the formations that play a large role, and not individual soldiers, how experienced and hardened the soldiers is doesn't play as a large role as how disciplined they are. Of course it helps them being disciplined, but it's not something invaluable.
Formations are an illusion. When you get on melee, they just don't count anymore.
Formations have an impact on initial contact. After that it is just chaos.
A veteran knows that, a non veteran doesn't, but will learn if he survives.
While I have no doubt they were chaotic, they weren't as chaotic as modern battles. Why? Because a longbow, crossbow, longsword, halberd, poleaxe, hand cannon or any other medieval or ancient weapon weren't as deadly as modern weapons. There existed protection against them other than just taking cover, such as armour and shields (no matter how much power the myths ascribe to hand cannons, arquebuses and crossbows, there existed plate armour capable of withstanding them. Well aside from the arbalest, but that took exceedingly long time to reload and was incredibly expensive).
I must say I disagree. They were much more chaotic. In addition, the crossbow could pierce through any armor. In fact, it was even considered an "unfair" weapon in the middle ages, because a peasant armed with a crossbow could kill with one shot a noble wearing heavy plate armor.
I am really surprised that the universal fact that "there is no training substitute for experience" on any department of life(whether it is warfare, technical labor, raising a family or whatever), is being argued in this thread...
EDIT: That said, I'm also against this idea because it would be needlessly complicated. I don't propose that rivers on snow or tundra functions like roads for movement bonii just because I like the idea of that the Teutonic Knights waged war in the winter, because the rivers froze over and could be used as roads while horses had difficulty crossing them in the summer.
This is a complete different matter. The fact that Kael is unlike to consider adding something like this, was something I stated from the beggining.
Pointing out that the idea has merit, IMO, and that could be a nice addition to a modmod, is a different thing.
I am satisfied with the current experience system, but I wouldn't say no to something adding more realism to the world of Erebus