This should be an easy one to name but I've completely lost it (mentally and literally), I believe I played this game on my old Apple //e.
In this game I remember clicking on the keyboard to send out WW2 vehicles and infantry which would move very slowly across the terrain (left to right). This terrain was at least several screens long. Each instance of sending out a unit would cost money. The computer opponent would do the same (its army appearing from the right side). Once they meet the armies would automatically fight each other. You could see flashes from the guns of your tanks destroying enemy fortifications (houses?) or slowly wearing down enemy units. Eventually your army would reach the right side of the screen and you would move on to the next mission (named after WW2 involved towns, ex: Saint Lo).