ORIGINAL: zwobot
. . .
At the moment I there are two Brigades in either side's OOB with one base each and I am not sure whether a Corps base would be needed in the scenario supplying the two Brigade bases?
There is something strange happening in my test scenario which might be caused by the lack of a higher echelon base on the map. In the attached screenshot you can see that III Brigade and X Brigade should be at the same level of the OOB however in the scenario X Brigade is a sub-unit of III Brigade...
Keep in mind that a "base" redistributes supplies arriving from an on-map Supply Entry Point (SEP) to the line units (SEP pushes supplies to the base, the base allows a unit to "pull" a subsistence from the base's allocation delivered by the SEP).
The "base" hierarchy relates to command and control.
If you have units under direct Corps control (Corps artillery for example), you need a Corps level base for them to draw supply.
If not, your brigade bases will receive supplies pushed from the SEP, and provide units under the Brigade's control access to those supplies.
I believe the subordination of one brigade to another has to do with span of control for the commander. The more efficient "on map" commander tends to be the "boss" for all units on the map.
My guess is if you want the brigades to operate independently, you need a division or corps HQ they report to so a less-better commanded unit to become subordinate to a peer with better command attributes.
Check the discussion of "on map boss" in the game manual for some advice.