Question about game's mechanics

[RVPERTVS]

Let me see if I got this right:

The tactic is called "stumbled upon attack", and basically it means facing and fighting the enemy from distance with some units or task force while another TF aproaches the same enemy behind a hill or whatever cover available. The point is to suppress and exhaust the enemy from distnace as much as posible so the covered and fresh force sudenly appears and finish the job at close range..is that right?

sIf that's so, it seems pretty good to me except for the fact that the aproaching force will lose the targeting bonus because of the movement, right?...but I can think of some interesting variations.....let me try it and we'll see

Does it have something to do with the reverse slope defence or they are different things?