How, exactly, does the general's unit rally routing troops? I know it's an F-key command, but does the general's unit actually have to be near the routing unit, and, if so, what exactly is the "effective radius" within which it will take effect? I've tried using it in a couple of battles, but it hasn't appeared to have any noticeable effects on my routing troops.

I guess what I'm trying to ask is, what's the most effective way to rally fleeing troops?