[Finalgenesis]

Friendly fire is a persistent fact of life as I understand it.

To my knowledge there's no way to have your archers stop firing keyed to whether your front line is engaged or not. "Fire and retreat" is the only common way for you to stop firing after a certain point, other then running out of ammo or losing arms on your archers.

Guiding wind would up your archer precision and cut down on FF abit if you have access to it, and using high parry shield (high prot a bonus especially if your not using crossbows) tanks in your front line would cut down on FF losses. I'm sure there are other useful spells for cutting down FF, I'll defer to the veterans on that.

I'm unfamiliar with Rohan, but if their cav has a good shield or if they have access to infantry with good shield (tower shield and the like for footies) and maybe good prot on top, it would make FF much less of an issue. If your cavalry are fragile to FF, you can always attack rear with them while holding the line with good shield troops.