Although not often I have seen Infantry rout en mass probably about a Division. In one MP battle, I advanced a screen of Medium and Heavy Cavalry towards the enemy line they saw the Cavalry depoy to charge and advance and that was it for the infantry the Rout started in a couple of infantry regiment, and then the panic spread, to the rest. Infantry surrendered which where pursued and a lot just kept routing for a while till they recovered.
The site I saw which was awesome, but I havent seen this very much at all.
So it is rare, but memorable