[Imp]

Varies on the situation but you use smoke as a screen. As cross said you want numerical superiorty, one way to do this is place smoke to take some defenders out of the picture leaving you to deal with the ones you can see. This leaves you free to deal with them as units on the flank will not be taking pot shots at you. Or place behind the group you want to attack if they have supporting fire further back. If you are in range to move to the killing zone (50m) you can now do so without danger & quickly move on.