Wonder if I can get clarification on supply sources. One source is a friendly city - does this still act as a supply source if its fortress is being besieged by enemy forces.
Also the rail source - can supply be traced by rail through a region which is occupied by enemy troops although they have yet to convert the rail track.
It seems to me that in both the above cases line of supply should be cut, although it doesn't seem to be.
Bern