As far as I understand, columns can only go up a path or down a path depending on their nationality. Blue goes up and red goes down. And the path should go in a general direction according to the compass.

Is there a trick to make a tank column seem to retreat in the mission itself? Maybe make a new reversed path?

There's code to determine whether a tank (or other moving column) retreats.  The other side just has to have overwhelming superiority for it to happen (like 5 to 1 odds based on the types of tanks present and the number of ground troops on each side).

Thanks for the info.