>>64061648
It's about morale.
>How did things go so terribly wrong?
Artillery. It removed the resolution of combat away from the combatants themselves into the concentration of fires away from the frontlines, where individual soldiers could see their opponents.

Soldiers used to benefit from portraying themselves ostentatiously, as their outfit would signal to the opposition that they were fighting against superior troops, thus destroying their morale, making them aware of the fact that they have no hope of victory. The more a unit focuses on being a "shock troop" the more ostentatious their uniform would be.
The average soldier would certainly despair at the sight of a noble, or a famous mercenary, or some other shock troop like a berserker or ulfhednar, who would be trained to a vastly superior degree, all the while also having a far more fatalist attitude compared to the common soldier. Thus, the portrayal of their status as a warrior was significantly important for the resolution of any tactical scenario.