Role of archers in low-tech parties?

[Agramer]

Originally Posted by Sword-dancer

i didn´t mean´t turning around the whole formation only to redirect the last lines zo form a shieldwall, Karree, testudo etc

same effect.

Forgot battle,but Salahadin pinned like that Christian rearguard and would annihilate it and subsequently whole army if not for Christian commander turning whole army timely about and charging to help.

Another example were Romans who got defeated by mounted archers(Crassus vs Parthians).