I've just played the first 50 or so turns of my first attempt at the full Grand Campaign scenario (as Prussia), and reached the point where the Russians turned up in force around Kolberg and Stettin (and what a lot of them there are!). I'm going to be restarting shortly, as I've inevitably learned lots of things over my first 50 turns that I wish I had applied properly from the beginning. One of the things I realised I had not been applying at all, was command structure above and beyond Corps level, so I decided to run the 2nd tutorial scenario again, which deals with building an army structure from scratch, as a refresher.
Quite straight forward, and the Shift key highlights, in blue, the command radius of a selected army commander (something I had completely forgotten to consider). However, I also discovered that if I select a Corps, or seemingly any non army leader unit, and then press the Shift key, I get a different type of display, with lines radiating out from the unit to each of it's neighbouring zones, in either blue or (more commonly) red. I've had a read through the manual, and can't seem to find any reference to this display. Could anyone shed any light on this - I have a feeling it might be important