Hello Pox, it is nice to see you here

I am using the ALT+left click behind the given unit. Of course it might not work all the time, it depends on a variety of factors: whether it is cav or inf, fighting vs cavs or inf, whether I have more than 1 units fighitng vs the same enemy unit, whether my unit is impetous or not, etc. Sometimes the best choice is not to withdraw but let the unit fight and die.